Light-emitting device and display panel

Abstract

The embodiment of the invention provides a light-emitting device and a display panel, relates to the technical field of display, and is used for improving the light-emitting efficiency of the light-emitting device and prolonging the service life of the light-emitting device. The light-emitting device comprises a cathode, an anode and at least one light-emitting unit, wherein the cathode and the anode are oppositely arranged, and the light-emitting unit is arranged between the cathode and the anode. The light-emitting unit comprises a light-emitting layer and a first type functional layer arranged on the side, close to the anode, of the light-emitting layer; the first type of functional layer comprises a first sub-functional layer and a second sub-functional layer; the material of the first sub-functional layer comprises a first functional material, and the material of the second sub-functional layer comprises a second functional material. Wherein the overlapping ratio of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%. The light-emitting device is used for displaying images.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a light-emitting device and a display panel. Background Art

[0002] Organic Light Emitting Diode (OLED) display panels have the advantages of self-luminescence, high color gamut, high saturation, and high response speed. They are widely used in display screens such as mobile phones, tablets, and car displays. Summary of the invention

[0003] The purpose of the embodiments of the present disclosure is to provide a light-emitting device and a display panel, which are used to improve the light-emitting efficiency and device life of the light-emitting device.

[0004] To achieve the above objectives, the embodiments of the present disclosure provide the following technical solutions:

[0005] In one aspect, a light-emitting device is provided. The light-emitting device includes a cathode and an anode arranged opposite to each other, and at least one light-emitting unit arranged between the cathode and the anode. The light-emitting unit includes: a light-emitting layer and a first type of functional layer arranged on the side of the light-emitting layer close to the anode; the first type of functional layer includes a first sub-functional layer and a second sub-functional layer; the material of the first sub-functional layer includes a first functional material, and the material of the second sub-functional layer includes a second functional material. The overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%.

[0006] When the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%, the HOMO state density of the first functional material (e.g., the material of the electron blocking layer) and the HOMO state density of the second functional material (e.g., the material of the hole transport layer) overlap each other, so that the hole transport rate between the first sub-functional layer (e.g., the electron blocking layer) and the second sub-functional layer (e.g., the hole transport layer) can be increased, and the hole transfer effect of the first type of functional layer (i.e., the hole transport functional layer) can be improved. In this way, holes and electrons can be relatively more balanced. On the one hand, the exciton recombination area can be relatively far away from the electron blocking layer, reducing the accumulation of electrons and excitons on the material of the electron blocking layer 1323, slowing down the degradation of the material of the electron blocking layer 1323, improving the stability of the material of the electron blocking layer 1323, and improving the life of the light-emitting device; on the other hand, the yield of excitons can be increased, the energy utilization rate can be improved, and the efficiency of the light-emitting device can be improved.

[0007] In some embodiments, the first sub-functional layer contacts the light-emitting layer; the material of the light-emitting layer includes a main material; wherein the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the main material is greater than 0% and less than or equal to 90%.

[0008] In some embodiments, the material of the light-emitting layer further includes a guest material; and at least one of the host material, the guest material and the first functional material is a deuterated material.

[0009] In some embodiments, the absolute value of the difference between the electron reorganization energy and the hole reorganization energy of the host material is less than or equal to 0.1 eV; and / or the hole mobility of the host material is greater than the electron mobility of the host material.

[0010] In some embodiments, the dipole moment of the first functional material is greater than 0D.

[0011] In some embodiments, the lowest bond dissociation energy of the first functional material in the ground state is greater than or equal to 2.40 eV; and / or the lowest bond dissociation energy of the first functional material in the anionic state is greater than or equal to 1.0 eV.

[0012] In some embodiments, the lowest of the bond dissociation energies of the host material in the ground state is greater than or equal to 1.50 eV; and / or the lowest of the bond dissociation energies of the guest material in the ground state is greater than or equal to 1.50 eV.

[0013] In some embodiments, the triplet energy level of the host material is less than the triplet energy level of the guest material; and / or the singlet energy level of the host material is greater than the singlet energy level of the guest material.

[0014] In some embodiments, the light-emitting unit further comprises a second type of functional layer disposed on the cathode side of the light-emitting layer; the second type of functional layer comprises a third sub-functional layer, the third sub-functional layer is in contact with the light-emitting layer; the material of the third sub-functional layer comprises a third functional material. The triplet energy level of the host material is less than the triplet energy level of the third functional material; and / or the triplet energy level of the host material is less than the triplet energy level of the first functional material.

[0015] In some embodiments, the host material is selected from any one of the structures shown in the following general formula (I).

[0016]

[0017] Wherein, R1, R2, R3, R4, R5, R6, R7 and R8 are the same or different and are independently selected from any one of hydrogen, deuterium, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted diarylamino, substituted or unsubstituted siloxane and substituted or unsubstituted silyl. L1 and L2 are the same or different and are independently selected from any one of single bond, substituted or unsubstituted arylene and substituted or unsubstituted heteroarylene. Ar1 and Ar2 are the same or different and are independently selected from substituted or unsubstituted aryl. At least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium.

[0018] In some embodiments, when the host material is a deuterated material, the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

[0019] In some embodiments, the guest material is selected from any one of the structures shown in the following general formula (II).

[0020]

[0021] Wherein, A, E and F are the same or different and are independently selected from any one of substituted or unsubstituted aromatic rings, substituted or unsubstituted heteroaromatic rings and substituted or unsubstituted cycloalkane rings; in the case where A, E and F are selected from any one of substituted aromatic rings, substituted heteroaromatic rings and substituted cycloalkane rings, the substituents may be connected with adjacent substituents to form a substituted or unsubstituted ring. X1 and X2 are the same or different and are independently selected from O, N(R a ) and C(R b R c ) in any one of R a , R b and R c are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl and substituted or unsubstituted heterocyclic. At least one of A, E and F contains deuterium.

[0022] In some embodiments, at least one of A, E, and F has a substituent comprising tert-butyl.

[0023] In some embodiments, when the guest material is a deuterated material, the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

[0024] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III).

[0025]

[0026] Wherein, Z is selected from O, S, N (R d ) and C(R e R f ) in any one of R d , R e and R f are the same or different and are independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. L3 and L4 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene and a substituted or unsubstituted heteroarylene. e and f are the same or different and are independently selected from any one of 1, 2, 3 and 4. Ar3, Ar4, Ar5 and Ar6 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl and a substituted or unsubstituted C2-C60 heteroaryl; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S. p and q are the same or different and are independently selected from any one of 0, 1 and 2; and the sum of p and q is greater than or equal to 1 and less than or equal to 2.

[0027] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III-A).

[0028]

[0029] wherein g and h are the same or different and are independently selected from any one of 0, 1, 2 and 3.

[0030] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (IV).

[0031]

[0032] Wherein, L5 is selected from any one of a single bond and a substituted or unsubstituted C6-C60 arylene group. Ar7 and Ar8 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S. R9 and R 10The same or different, independently selected from any one of hydrogen, deuterium, halogen, cyano, nitro, amino, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C3-C60 cycloalkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C6-C60 aryl and substituted or unsubstituted C2-C60 heteroaryl; or can be connected with adjacent substituents to form a substituted or unsubstituted ring; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S. m and n are the same or different, independently selected from any one of 1, 2, 3 and 4. At least one R9 is deuterium. At least one R 10 For deuterium.

[0033] In some embodiments, when the first functional material is a deuterated material, the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0034] In some embodiments, the light-emitting device includes at least two light-emitting units, and the at least two light-emitting units are stacked. The light-emitting device also includes a charge generation layer located between two adjacent light-emitting units; the charge generation layer includes a hole generation layer and an electron generation layer stacked; the electron generation layer is closer to the anode than the hole generation layer.

[0035] In some embodiments, the structural formula of the second functional material is as follows.

[0036]

[0037] In some embodiments, the light emitting device is configured to emit light of a first wavelength, and the light of the first wavelength is blue light.

[0038] In another aspect, a display panel is provided, wherein the display panel comprises a plurality of light-emitting devices as described in any of the above embodiments and a plurality of pixel driving circuits, wherein the pixel driving circuits are electrically connected to the light-emitting devices and are used to drive the light-emitting devices to emit light.

[0039] The beneficial effects that can be achieved by the display panel provided by some embodiments of the present disclosure are the same as the beneficial effects that can be achieved by a light-emitting device provided by the above technical solution, and will not be repeated here.

[0040] On the other hand, a display panel is provided. The display panel includes a substrate and a plurality of light-emitting devices; the plurality of light-emitting devices are arranged on the substrate and arranged along a first direction, and the first direction is parallel to the plane where the substrate is located; the plurality of light-emitting devices include at least one first light-emitting device, at least one second light-emitting device and at least one third light-emitting device, the first light-emitting device is configured to emit blue light; the second light-emitting device is configured to emit green light; the third light-emitting device is configured to emit red light; wherein each of the plurality of light-emitting devices includes a cathode and an anode arranged opposite to each other, and at least one light-emitting unit arranged between the cathode and the anode; the light-emitting unit includes a light-emitting layer; the number of light-emitting units included in each of the plurality of light-emitting devices is n, and n is a positive integer greater than or equal to 1; the thickness of the light-emitting layer of the Nth light-emitting unit of the third light-emitting device is greater than the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device; the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device is greater than the thickness of the light-emitting layer of the Nth light-emitting unit of the first light-emitting device, wherein N is a positive integer less than or equal to n.

[0041] It can be understood that the mobility of carriers in the light-emitting layer of the third light-emitting device is greater than the mobility of carriers in the light-emitting layer of the second light-emitting device, and the mobility of carriers in the light-emitting layer of the second light-emitting device is greater than the mobility of carriers in the light-emitting layer of the first light-emitting device. Through the above-mentioned arrangement, the thickness of the light-emitting layer of the first light-emitting device, the second light-emitting device, and the third light-emitting device can be matched with the mobility of the carriers. In this way, the areas where holes and electrons recombine to form excitons in the first light-emitting device, the second light-emitting device, and the third light-emitting device can be made relatively consistent, which can alleviate the problem of color deviation.

[0042] In some embodiments, the difference between the thickness of the light-emitting layer of the Nth light-emitting unit of the third light-emitting device and the thickness of the light-emitting layer of the Nth light-emitting unit of the first light-emitting device is a first thickness difference; the difference between the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device and the thickness of the light-emitting layer of the Nth light-emitting unit of the first light-emitting device is a second thickness difference; the difference between the thickness of the light-emitting layer of the Nth light-emitting unit of the third light-emitting device and the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device is a third thickness difference; wherein, the ratio of the first thickness difference to the second thickness difference is greater than or equal to 1.5 and less than or equal to 2; the ratio of the third thickness difference to the second thickness difference is greater than or equal to 1 and less than or equal to 1.5.

[0043] In some embodiments, the light-emitting unit also includes a first type of functional layer arranged on the anode side of the light-emitting layer; the first type of functional layer includes a first sub-functional layer in contact with the light-emitting layer; the difference between the thickness of the first sub-functional layer of the Nth light-emitting unit of the third light-emitting device and the thickness of the first sub-functional layer of the Nth light-emitting unit of the first light-emitting device is a fourth thickness difference; the difference between the thickness of the first sub-functional layer of the Nth light-emitting unit of the second light-emitting device and the thickness of the first sub-functional layer of the Nth light-emitting unit of the first light-emitting device is a fifth thickness difference; the ratio of the fourth thickness difference to the fifth thickness difference is greater than or equal to 1.1 and less than or equal to 1.5.

[0044] In some embodiments, the light-emitting unit further includes a second type of functional layer disposed on the cathode side of the light-emitting layer; a ratio of a thickness of the first type of functional layer to a thickness of the second type of functional layer is greater than or equal to 1 and less than or equal to 5.

[0045] In some embodiments, the material of the light-emitting layer includes a guest material, which is configured to emit light of a set wavelength; the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is greater than or equal to 650 and less than or equal to 1300; and / or the relative molecular weight of the guest material of the light-emitting layer of the second light-emitting device is greater than or equal to 700 and less than or equal to 1400; and / or the relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device is greater than or equal to 700 and less than or equal to 1500.

[0046] In some embodiments, the absolute value of the difference between the relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is less than or equal to 600; and / or the absolute value of the difference between the relative molecular weight of the guest material of the light-emitting layer of the second light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is less than or equal to 500.

[0047] In some embodiments, the difference between the relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is a first relative molecular weight difference; the difference between the relative molecular weight of the guest material of the light-emitting layer of the second light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is a second relative molecular weight difference. The ratio of the absolute value of the first relative molecular weight difference to the absolute value of the second relative molecular weight difference is greater than or equal to 0.5 and less than or equal to 6.

[0048] In some embodiments, the optical path of the light in the light-emitting layer of the light-emitting unit near the anode of the first light-emitting device and the first type of functional layer is the first optical path; the optical path of the light in the light-emitting layer of the light-emitting unit near the anode of the second light-emitting device and the first type of functional layer is the second optical path; the optical path of the light in the light-emitting layer of the light-emitting unit near the anode of the third light-emitting device and the first type of functional layer is the third optical path. The ratio of the third optical path to the second optical path is greater than or equal to 1.1 and less than or equal to 1.25; the ratio of the third optical path to the first optical path is greater than or equal to 1.25 and less than or equal to 1.45; the ratio of the second optical path to the first optical path is greater than or equal to 1.05 and less than or equal to 1.25.

[0049] In some embodiments, the light emitting device includes a first light emitting unit and a second light emitting unit; the first light emitting unit is closer to the anode than the second light emitting unit; and the ratio between the thickness of the light emitting layer of the first light emitting unit and the thickness of the light emitting layer of the second light emitting unit is greater than or equal to 0.8 and less than or equal to 1.5.

[0050] In some embodiments, when the light-emitting unit includes a first type of functional layer and a second type of functional layer, the first type of functional layer also includes a second sub-functional layer and a fourth sub-functional layer, and the fourth sub-functional layer, the second sub-functional layer and the first sub-functional layer are arranged in sequence in a direction away from the anode; the second type of functional layer includes a third sub-functional layer, a fifth sub-functional layer and a sixth sub-functional layer; the sixth sub-functional layer, the fifth sub-functional layer and the third sub-functional layer are arranged in sequence in a direction away from the cathode. The sum of the thickness of the second sub-functional layer of the second light-emitting unit and the thickness of the fifth sub-functional layer is the first thickness sum, and the sum of the thickness of the second sub-functional layer of the first light-emitting unit and the thickness of the fifth sub-functional layer is the second thickness sum. The ratio between the first thickness sum and the second thickness sum is greater than or equal to 2 and less than or equal to 4.

[0051] In some embodiments, the sum of the thickness of the first subfunctional layer of the second light-emitting unit and the thickness of the second subfunctional layer is the third thickness sum, and the sum of the thickness of the first subfunctional layer of the first light-emitting unit and the thickness of the second subfunctional layer is the fourth thickness sum; the ratio between the third thickness sum and the fourth thickness sum is greater than or equal to 2 and less than or equal to 5.

[0052] In some embodiments, the sum of the thickness of the third sub-functional layer of the second light-emitting unit and the thickness of the fifth sub-functional layer is the fifth thickness sum, and the sum of the thickness of the third sub-functional layer of the first light-emitting unit and the thickness of the fifth sub-functional layer is the sixth thickness sum. The ratio of the fifth thickness sum to the sixth thickness sum is greater than or equal to 1.5 and less than or equal to 3.

[0053] In some embodiments, when the first type of functional layer further includes a second sub-functional layer, the material of the light-emitting layer includes a host material and a guest material; the material of the first sub-functional layer includes a first functional material, and the material of the second sub-functional layer includes a second functional material. Wherein, the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%; and / or, the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the host material is greater than 0% and less than or equal to 90%.

[0054] In some embodiments, at least one of the host material, the guest material, and the first functional material is a deuterated material.

[0055] In some embodiments, the absolute value of the difference between the electron reorganization energy and the hole reorganization energy of the host material is less than or equal to 0.1 eV; and / or the hole mobility of the host material is greater than the electron mobility of the host material.

[0056] In some embodiments, the dipole moment of the first functional material is greater than 0D.

[0057] In some embodiments, the lowest bond dissociation energy of the first functional material in the ground state is greater than or equal to 2.40 eV; and / or the lowest bond dissociation energy of the first functional material in the anionic state is greater than or equal to 1.0 eV.

[0058] In some embodiments, the lowest of the bond dissociation energies of the host material in the ground state is greater than or equal to 1.50 eV; and / or the lowest of the bond dissociation energies of the guest material in the ground state is greater than or equal to 1.50 eV.

[0059] In some embodiments, the triplet energy level of the host material is less than the triplet energy level of the guest material; and / or the singlet energy level of the host material is greater than the singlet energy level of the guest material.

[0060] In some embodiments, when the light-emitting unit further includes a third sub-functional layer, the third sub-functional layer is in contact with the light-emitting layer; the material of the third sub-functional layer includes a third functional material. The triplet energy level of the host material is less than the triplet energy level of the third functional material; and / or the triplet energy level of the host material is less than the triplet energy level of the first functional material.

[0061] In some embodiments, the host material is selected from any one of the structures shown in the following general formula (I).

[0062]

[0063] Wherein, R1, R2, R3, R4, R5, R6, R7 and R8 are the same or different and are independently selected from any one of hydrogen, deuterium, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted diarylamino, substituted or unsubstituted siloxane and substituted or unsubstituted silyl. L1 and L2 are the same or different and are independently selected from any one of single bond, substituted or unsubstituted arylene and substituted or unsubstituted heteroarylene. Ar1 and Ar2 are the same or different and are independently selected from substituted or unsubstituted aryl. At least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium.

[0064] In some embodiments, when the host material is a deuterated material, the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

[0065] In some embodiments, the guest material is selected from any one of the structures shown in the following general formula (II).

[0066]

[0067] Wherein, A, E and F are the same or different and are independently selected from any one of substituted or unsubstituted aromatic rings, substituted or unsubstituted heteroaromatic rings and substituted or unsubstituted cycloalkane rings; in the case where A, E and F are selected from any one of substituted aromatic rings, substituted heteroaromatic rings and substituted cycloalkane rings, the substituents may be connected with adjacent substituents to form a substituted or unsubstituted ring. X1 and X2 are the same or different and are independently selected from O, N(R a ) and C(R b R c ) in any one of R a , R b and R c are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl and substituted or unsubstituted heterocyclic. At least one of A, E and F contains deuterium.

[0068] In some embodiments, at least one of A, E, and F has a substituent comprising tert-butyl.

[0069] In some embodiments, when the guest material is a deuterated material, the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

[0070] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III).

[0071]

[0072] Wherein, Z is selected from O, S, N (R d ) and C(R e R f ) in any one of R d , R e and R f are the same or different and are independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. L3 and L4 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene and a substituted or unsubstituted heteroarylene. e and f are the same or different and are independently selected from any one of 1, 2, 3 and 4. Ar3, Ar4, Ar5 and Ar6 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl and a substituted or unsubstituted C2-C60 heteroaryl; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S. p and q are the same or different and are independently selected from any one of 0, 1 and 2; and the sum of p and q is greater than or equal to 1 and less than or equal to 2.

[0073] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III-A).

[0074]

[0075] wherein g and h are the same or different and are independently selected from any one of 0, 1, 2 and 3.

[0076] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (IV).

[0077]

[0078] Wherein, L5 is selected from any one of a single bond and a substituted or unsubstituted C6-C60 arylene group. Ar7 and Ar8 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S. R9 and R 10The same or different, independently selected from any one of hydrogen, deuterium, halogen, cyano, nitro, amino, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C3-C60 cycloalkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C6-C60 aryl and substituted or unsubstituted C2-C60 heteroaryl; or can be connected with adjacent substituents to form a substituted or unsubstituted ring; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S. m and n are the same or different, independently selected from any one of 1, 2, 3 and 4. At least one R9 is deuterium. At least one R 10 For deuterium.

[0079] In some embodiments, when the first functional material is a deuterated material, the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0080] In some embodiments, the light-emitting device includes at least two light-emitting units, and the at least two light-emitting units are stacked. The light-emitting device also includes a charge generation layer located between two adjacent light-emitting units; the charge generation layer includes a hole generation layer and an electron generation layer stacked; the electron generation layer is closer to the anode than the hole generation layer.

[0081] In some embodiments, the structural formula of the second functional material is as follows.

[0082]

[0083] In some embodiments, the host material is the host material of the light-emitting layer of the first light-emitting device; the guest material is the guest material of the light-emitting layer of the first light-emitting device; the first functional material is the material of the first sub-functional layer of the first light-emitting device; the second functional material is the material of the second sub-functional layer of the first light-emitting device. In the case where the light-emitting unit further includes a third sub-functional layer, the third functional material is the material of the third sub-functional layer of the first light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings required to be used in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the product involved in the embodiments of the present disclosure, the actual process of the method, the actual timing of the signal, etc.

[0085] Figure 1 is a structural diagram of a display device according to some embodiments;

[0086] Figure 2 is a structural diagram of a display panel according to some embodiments;

[0087] Figure 3 is a structural diagram of a display panel according to some further embodiments;

[0088] Figure 4 is a structural diagram of a display panel according to some further embodiments;

[0089] Figure 5 is a structural diagram of a display panel according to some further embodiments;

[0090] Figure 6 is a structural diagram of a light emitting device according to some embodiments;

[0091] Figure 7 is a structural diagram of a light emitting device according to some further embodiments;

[0092] Figure 8 is a structural diagram of a display panel according to some further embodiments;

[0093] Fig. 9 is a structural diagram of a light emitting device according to some further embodiments;

[0094] Fig.10 is a structural diagram of a display panel according to some further embodiments;

[0095] Fig.11 is a diagram showing changes in exciton intensity at different positions in a light-emitting layer according to some embodiments;

[0096] Fig.12 A molecular packing diagram during state density simulation calculation according to some embodiments;

[0097] Fig.13 is a state density distribution diagram of the material of the electron blocking layer and the material of the hole transport layer according to some embodiments;

[0098] Fig.14 A diagram of a process of generating singlet excitons during triplet-triplet fusion according to some embodiments;

[0099] Fig.15 is a graph showing changes in bond dissociation energy before and after deuteration of a material according to some embodiments;

[0100] Fig.16 is a structural diagram of a light emitting device according to some other embodiments;

[0101] Fig.17 is a structural diagram of a display panel according to some other embodiments. DETAILED DESCRIPTION

[0102] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0103] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and other forms thereof, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open, inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0104] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0105] “At least one of A, B, and C” has the same meaning as “at least one of A, B, or C” and both include the following combinations of A, B, and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C.

[0106] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0107] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of variation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0108] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism may be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity may also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality may be, for example, the difference between the two equalities is less than or equal to 5% of either one.

[0109] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0110] Exemplary embodiments are described herein with reference to cross-sectional views and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of the layers and the area of ​​the regions are exaggerated for clarity. Therefore, variations in the shapes relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes of the regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0111] It should be noted that, for example, 11-1 in the drawings of the present disclosure indicates that component 11 belongs to component 1, for example, Figure 2 221-220 in the figure indicate that the pixel defining layer 221 belongs to the light-emitting functional layer 220, and other similar reference numerals in the drawings also follow the above description. For example, 1 / 2 in the drawings of the present disclosure indicates that structure 1 and structure 2 can refer to the structure, for example, Figure 3 The reference numeral 101 / 100 indicates that both the first light emitting device 101 and the light emitting device 100 can refer to this structure, and other similar reference numerals appearing in the drawings also follow the above description.

[0112] like Figure 1 As shown, some embodiments of the present disclosure provide a display device 300 , which includes: a display panel 200 .

[0113] The display device 300 may be, for example, an OLED (Organic Light Emitting Diode) display device 300 .

[0114] For example, Figure 1 As shown, the display device 300 further includes a driving chip 310. The driving chip 310 is used to drive the display panel 200 to display.

[0115] In addition, the display device 300 may also include an under-screen camera and an under-screen fingerprint recognition sensor, so that the display device 300 can realize a variety of different functions such as taking pictures, recording videos, fingerprint recognition or face recognition.

[0116] The display device 300 described above can be any display device that displays either motion (e.g., video) or fixed (e.g., still images) and whether text or images. More specifically, it is expected that the display device 300 of the embodiment described can be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, video cameras, game consoles, watches, clocks, calculators, television monitors, flat panel displays, computer monitors, automotive displays (e.g., odometer displays, etc.), navigators, cockpit controls and / or displays, displays of camera views (e.g., displays of rear-view cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0117] In some embodiments, Figure 2 As shown, the display panel 200 includes a substrate 210 and a light-emitting functional layer 220 disposed on the substrate 210. The light-emitting functional layer 220 includes a plurality of light-emitting devices 100. The plurality of light-emitting devices 100 are arranged along a first direction X, and the first direction X is parallel to the plane where the substrate 210 is located.

[0118] For example, the substrate 210 may be a transparent substrate. The material of the substrate 210 may be a rigid material, such as glass; or the material of the substrate 210 may be a flexible material, such as polyimide.

[0119] In some examples, such as Figure 2As shown, the display panel 200 further includes an array layer 230 disposed between the substrate 210 and the light-emitting functional layer 220, and the array layer 230 includes a plurality of pixel driving circuits 231, wherein the pixel driving circuits 231 include a plurality of transistors TFT. Each pixel driving circuit 231 is electrically connected to a light-emitting device 100, and is used to drive the light-emitting device 100 to emit light.

[0120] Exemplarily, in the display panel 200, the pixel driving circuit 231 can generate a driving current. Each light emitting device 100 can emit light under the driving action of the driving current generated by the corresponding pixel driving circuit 231, and the lights emitted by the multiple light emitting devices 100 cooperate with each other, so that the display panel 200 realizes the display function.

[0121] In some examples, such as Figure 2 As shown, the display panel 200 also includes an encapsulation layer 240 , and the array layer 230 , the light-emitting functional layer 220 and the encapsulation layer 240 are stacked on the substrate 210 , and the array layer 230 , the light-emitting functional layer 220 and the encapsulation layer 240 are arranged in sequence in a direction away from the substrate 210 .

[0122] Exemplarily, the display panel 200 may be an OLED display panel, in which case the encapsulation layer 240 covers the light-emitting device 100 to encapsulate the light-emitting device 100 to prevent moisture and oxygen in the external environment from entering the display panel 200 and damaging the organic material in the light-emitting device 100, thereby shortening the life of the OLED display panel 200.

[0123] In some embodiments, Figure 2 and Figure 3 As shown, in the display panel 200 , the light-emitting functional layer 220 further includes a pixel defining layer 221 disposed on one side of the substrate 210 . The pixel defining layer 221 has a plurality of openings Q. The plurality of light-emitting devices 100 can be disposed correspondingly to the plurality of openings Q one by one.

[0124] In some embodiments, Figure 3 to Figure 5 As shown, the plurality of light emitting devices 100 of the display panel 200 include a first light emitting device 101, a second light emitting device 102 and a third light emitting device 103. Under the action of a driving voltage, the first light emitting device 101 is configured to emit light of a first wavelength, which is blue light, the second light emitting device 102 is configured to emit light of a second wavelength, which is green light, and the third light emitting device 103 is configured to emit light of a third wavelength, which is red light.

[0125] By setting up multiple light-emitting devices 100 including a first light-emitting device 101, a second light-emitting device 102 and a third light-emitting device 103, the brightness (gray scale) of the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103 can be adjusted respectively, and the display of multiple colors can be achieved through color combination and superposition, thereby realizing full-color display of the display panel 200.

[0126] It should be noted that Figure 4 and Figure 5 This is a simplified schematic diagram obtained after removing other film layers in the display panel 200 except for the film layers related to the light emitting device 100. Figure 4 and Figure 5 In the embodiment, the plurality of light emitting devices 100 are, for example, a first light emitting device 101 , a second light emitting device 102 and a third light emitting device 103 .

[0127] In some embodiments, Figure 3 to Figure 7 As shown, the light emitting device 100 includes an anode 11 and a cathode 12 which are stacked, and at least one light emitting unit 13 which is disposed between the anode 11 and the cathode 12. The light emitting unit 13 includes a light emitting layer 131.

[0128] During operation, voltage is applied to the anode 11 and the cathode 12 respectively to generate an electric field between the two, which can drive the holes in the anode 11 and the electrons in the cathode 12 to recombine in the light-emitting layer 131, thereby emitting light.

[0129] In some examples, such as Figure 3 As shown, the anode 11 may be located on a side of the light emitting unit 13 close to the substrate 210, and the cathode 12 may be located on a side of the light emitting unit 13 away from the substrate 210. In other examples, the anode 11 may be located on a side of the light emitting unit 13 away from the substrate 210, and the cathode 12 may be located on a side of the light emitting unit 13 close to the substrate 210.

[0130] Exemplarily, in order to ensure that the light-emitting device 100 can effectively emit light, the anode 11 can be made of a material with a high work function, so that the holes in the anode 11 can be effectively migrated to the light-emitting layer 131 of the light-emitting unit 13 under the drive of the electric field, thereby combining with the electrons of the cathode 12 to emit light. The material of the anode 11 can be a transparent conductive metal oxide material, for example, the material of the anode 11 can be indium tin oxide (Indium Tin Oxide, ITO) or indium zinc oxide (Indium Zinc Oxide, IZO). Alternatively, the anode 11 can be a composite electrode containing multiple materials, for example, the material of the anode 110 can be ITO / Ag / ITO, Ag / IZO, CNT / ITO, CNT / IZO, GO / ITO or GO / IZO, etc., wherein Ag is silver, CNT is carbon nanotube (Carbonnanotube), and GO is graphene oxide (graphene oxide).

[0131] In some examples, the cathode 12 may be made of a material with a low work function, so that the electrons of the cathode 12 can be more easily injected into the target film layer (for example, the electron injection layer 1331. For the introduction of the electron injection layer 1331, see the following content, which will not be repeated here). In this way, the electrons in the cathode 12 can be effectively migrated to the light-emitting layer 131 of the light-emitting unit 13 under the drive of the electric field, thereby recombining with the holes in the anode 11 to emit light. In addition, the cathode 12 must also have good light transmittance and electrical conductivity. The material of the cathode 12 can be a metal material, a metal oxide or a metal alloy, such as aluminum (Al), silver (Ag), gold (Au), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium (Li), potassium (K), sodium (Na), tin (Sn), titanium (Ti), lead (Pb), samarium (Sm), yttrium (Y), indium tin oxide (ITO), magnesium silver alloy (Mg:Ag), ytterbium gold alloy (Yb:Au), ytterbium silver alloy (Yb:Ag), lithium aluminum alloy (Li:Al) or lithium calcium magnesium alloy (Li:Ca:Al), etc.; or, the material of cathode 12 can be a laminated material, such as magnesium / aluminum (Mg / Al), magnesium / silver (Mg / Ag), aluminum / silver (Al / Ag), aluminum / gold (Al / Au), ytterbium / gold (Yb / Au), ytterbium / silver (Yb / Ag), calcium / magnesium (Ca / Mg), calcium / silver (Ca / Ag), barium / silver (Ba / Ag), etc.

[0132] In some embodiments, Figure 8As shown, in the display panel 200, a covering layer 15 is further provided between the encapsulation layer 240 and the cathode 12. The material forming the covering layer 15 is, for example, a material with a high refractive index. By providing the covering layer 15, the high refractive property of the material can be utilized to improve the light extraction efficiency of the light emitting device 100, and the efficiency and brightness of the light emitting device 100 when lit can be improved.

[0133] It should be noted that Figure 8 This is a simplified schematic diagram obtained after removing other film layers in the display panel 200 except for the film layers related to the light emitting device 100. Figure 8 In the embodiment, the light emitting device 100 is, for example, a first light emitting device 101 .

[0134] In some examples, the structural formula of the material of the cover layer 15 may be as shown below.

[0135]

[0136] In some examples, such as Figure 3 , Figure 4 , Figure 6 and Figure 8 As shown, the light emitting device 100 includes a light emitting unit 13. In this case, the light emitting device 100 is a single-layer light emitting device, and the anode 11, the light emitting unit 13, and the cathode 12 are stacked along the second direction Y, and the second direction Y intersects with the first direction X. In other examples, such as Figure 5 , Figure 7 , Fig. 9 and Fig.10 As shown, the light emitting device 100 includes a plurality of (for example, two) stacked light emitting units 13. At this time, the light emitting device 100 is a stacked light emitting device, and the anode 11, the plurality of light emitting units 13, and the cathode 12 are stacked along the second direction Y.

[0137] For example, Figures 3 to 10 As shown, the second direction Y is perpendicular to the first direction X.

[0138] In some embodiments, Figure 5 , Figure 7 , Fig. 9 and Fig.10 As shown, when the light-emitting device 100 includes a plurality of light-emitting units 13 , that is, when the light-emitting device 100 includes at least two light-emitting units 13 , the light-emitting device 100 further includes a charge generation layer 14 , and the charge generation layer 14 is located between two adjacent light-emitting units 13 among the plurality of light-emitting units 13 .

[0139] Through the charge generation layer 14, the plurality of light-emitting units 13 can be sequentially connected in a direction perpendicular to the light-emitting surface (e.g., the second direction Y). Moreover, the charge generation layer 14 in the stacked OLED light-emitting device 100 not only plays a role in connecting the light-emitting units 13, but also helps to improve the generation efficiency of charges (holes or electrons), which can have a significant impact on the performance of the light-emitting device 100.

[0140] In some examples, such as Figure 5 , Figure 7 , Fig. 9 and Fig.10 As shown, the charge generation layer 14 includes an electron generation layer 141 and a hole generation layer 142 which are stacked; the electron generation layer 141 is closer to the anode 11 than the hole generation layer 142 .

[0141] Exemplarily, the above-mentioned electron generation layer 141 may also be referred to as an N-type charge generation layer. The thickness of the electron generation layer 141 may be 15 nm to 25 nm. The material of the electron generation layer 141 may be an electronic type material, for example, an electronic type material containing phenanthroline or phosphine oxide. In some examples, the electron generation layer 141 contains a dopant, and the dopant may be an alkali metal, an alkaline earth metal and its oxide. Among them, the alkali metal is, for example, lithium (Li), sodium (Na), potassium (K) or cesium (Cs), and the alkaline earth metal is, for example, magnesium (Mg), strontium (Sr), barium (Ba) or radium (Ra).

[0142] Exemplarily, the hole generation layer 142 may also be referred to as a P-type charge generation layer. The thickness of the hole generation layer 142 may be 5 nm to 15 nm. The material of the hole generation layer 142 may be a hole-type material, such as N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) or N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD). In some examples, the hole generation layer 142 contains a dopant, such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN) or 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ).

[0143] In some embodiments, Figures 3 to 10As shown, in order to improve the luminous efficiency of the light-emitting device 100, the light-emitting unit 13 also includes a hole transport functional layer 132, which is located on the side of the light-emitting layer 131 close to the anode 11 and in contact with the light-emitting layer 131. The hole transport functional layer 132, for example, includes at least one of a hole injection layer 1321 (Hole Inject Layer, HIL), a hole transport layer 1322 (Hole Transport Layer, HTL) and an electron blocking layer 1323 (Electron Blocking Layer, EBL) that are stacked. When the hole transport functional layer 132 includes the hole injection layer 1321, the hole transport layer 1322, and the electron blocking layer 1323, the hole injection layer 1321, the hole transport layer 1322, and the electron blocking layer 1323 are arranged in sequence in a direction away from the anode 11, and the electron blocking layer 1323 is in contact with the light-emitting layer 131.

[0144] In some embodiments, Figures 3 to 10 As shown, in order to improve the luminous efficiency of the light-emitting device 100, the light-emitting unit 13 also includes an electron transport functional layer 133, which is located on the side of the light-emitting layer 131 close to the cathode 12 and in contact with the light-emitting layer 131. The electron transport functional layer 133, for example, includes at least one of a stacked electron injection layer 1331 (Electron Inject Layer, EIL), an electron transport layer 1332 (Electron Transport Layer, ETL), and a hole blocking layer 1333 (Hole Blocking Layer, EBL). When the electron transport functional layer 133 includes an electron injection layer 1331, an electron transport layer 1332, and a hole blocking layer 1333, the electron injection layer 1331, the electron transport layer 1332, and the hole blocking layer 1333 are arranged in sequence in a direction away from the cathode 12, and the hole blocking layer 1333 is in contact with the light-emitting layer 131.

[0145] By setting up the film layers such as the hole injection layer 1321, the hole transport layer 1322, the electron blocking layer 1323, the electron injection layer 1331, the electron transport layer 1332, and the hole blocking layer 1333, it is equivalent to setting up transition steps between the anode 11 and the light-emitting layer 131, and between the cathode 12 and the light-emitting layer 131, thereby reducing the barrier height that needs to be overcome for carrier transition, thereby making the light-emitting efficiency higher.

[0146] Exemplarily, the hole transport functional layer 132 is configured to transport holes and / or to block electrons and excitons generated in the light emitting layer 131. For example, the hole injection layer 1321 can be configured to reduce the hole injection barrier and improve the hole injection efficiency. The hole transport layer 1322 can be configured to transport holes. The electron blocking layer 1323 can be configured to transport holes, block electrons and excitons generated in the light emitting layer 131.

[0147] Exemplarily, the electron transport functional layer 133 is configured to transport electrons and / or block holes and excitons generated in the light emitting layer 131 .

[0148] Exemplarily, the thickness of the hole injection layer 1321 may be 5 nm to 30 nm. The material of the hole injection layer 1321 may be an inorganic oxide, such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide or manganese oxide, etc.; or, the material of the hole injection layer 1321 may also be a dopant containing a strong electron-withdrawing material, such as 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ), 2,3,6,7,10,11 -hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN) or pyrazolo[2,3-F][1,10]phenanthroline-2,3-dicarbonitrile (PPDN); or, the material of the hole injection layer 1321 can also be a material obtained by P-type doping the material of the hole transport layer 1322, in which case the thickness of the hole injection layer 1321 can be 5nm to 20nm; the process of forming the hole injection layer 1321 is, for example, to form the hole transport layer 1322 material and the P-type dopant by co-evaporation. Among them, the structural formulas of F4TCNQ, HATCN and PPDN are as shown below.

[0149]

[0150] For example, the thickness of the hole transport layer 1322 of a single-layer light-emitting device may be 100 nm to 2000 nm; the thickness of the hole transport layer 1322 of a stacked-layer light-emitting device may be 15 nm to 25 nm. The material of the hole transport layer 1322 has good hole transport characteristics and can be an aromatic amine material or a carbazole material, such as N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), 4,4',4"-tri(carbazole-9-yl)triphenylamine (TCTA), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), (9-phenylfluorene-9-yl)triphenylamine (BAFLP) or bis[n-(9,9-dimethylfluorene-2-yl)-n-phenylamino]biphenyl (DFLDPBi), etc. The structural formulas of NPB, TCTA and TAPC are as shown below.

[0151]

[0152] Exemplarily, the thickness of the electron blocking layer 1323 of the single-layer light-emitting device may be 5 nm to 100 nm; the thickness of the electron blocking layer 1323 of the stacked light-emitting device may be 5 nm to 15 nm. The material of the electron blocking layer 1323 has good hole transport characteristics and may be an aromatic amine material or a carbazole material, such as 4,4'-di(9-carbazole)biphenyl (CBP) or 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9h-carbazole (PCzPA).

[0153] Exemplarily, the thickness of the electron injection layer 1331 may be 1 nm to 10 nm. The material of the electron injection layer 1331 has the characteristics of electron transport capability, and has the effect of injecting electrons from the cathode 12, and has good film forming capability, and may be an alkali metal or metal, such as lithium fluoride LiF, ytterbium Yb, magnesium Mg, calcium Ca, or a compound of the above metals.

[0154] Exemplarily, the thickness of the electron transport layer 1332 of the single-layer light-emitting device may be 20nm to 100nm; the thickness of the electron transport layer 1332 of the stacked light-emitting device may be 20nm to 100nm. The thickness of the hole blocking layer 1333 of the single-layer light-emitting device may be 5nm to 100nm; the thickness of the hole blocking layer 1333 of the stacked light-emitting device may be 5nm to 15nm. The materials of the electron transport layer 1332 and the hole blocking layer 1333 may be aromatic heterocyclic compounds, such as imidazole derivatives, pyrimidine derivatives, oxazine derivatives, compounds containing nitrogen-containing six-membered ring structures, or compounds having phosphine oxide-based substituents on heterocyclic rings. Among them, imidazole derivatives are, for example, benzimidazole derivatives, imidazopyridine derivatives, or benzimidazolephenanthridine derivatives; oxazine derivatives are, for example, triazine derivatives, etc.; compounds containing nitrogen-containing six-membered ring structures are, for example, quinoline derivatives, isoquinoline derivatives, or phenanthroline derivatives, etc. In some examples, the materials of the electron transport layer 1332 and the hole blocking layer 1333 are 2,2'-(1,3-phenyl)bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (p-EtTAZ), 4,7-diphenyl-1,10-phenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), or 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), etc. The structural formulas of BPhen and TPBi are as shown below.

[0155]

[0156] For example, the thickness of the light emitting layer 131 of the single-layer light emitting device may be 20 nm to 100 nm; the thickness of the light emitting layer 131 of the stacked-layer light emitting device may be 10 nm to 20 nm.

[0157] In some embodiments, Figure 4 , Figure 5 and Fig.10 As shown, in the case where the plurality of light-emitting devices 100 include a first light-emitting device 101, a second light-emitting device 102, and a third light-emitting device 103, the cathodes 12 of the plurality of light-emitting devices 100 are a structure in which the entire layer is connected, that is, the cathode 12 may be a common electrode shared by the plurality of light-emitting devices 100. The hole injection layer 1321 of the plurality of light-emitting devices 100 may also be a structure in which the entire layer is connected, that is, the hole injection layer 1321 may be a common film layer shared by the plurality of light-emitting devices 100. The hole transport layer 1322, the electron blocking layer 1323, the electron injection layer 1331, the electron transport layer 1332, the hole blocking layer 1333, the electron generation layer 141, and the hole generation layer 142 may also be common film layers shared by the plurality of light-emitting devices 100, which will not be described in detail here.

[0158] For example, Figure 3 As shown, when the cathode 12 is a common electrode shared by a plurality of light emitting devices 100 , the cathode 12 is simultaneously formed on a side of the pixel defining layer 221 away from the substrate 210 .

[0159] In some embodiments, Figure 4 , Figure 5 and Fig.10 As shown, in the case where the plurality of light-emitting devices 100 include a first light-emitting device 101, a second light-emitting device 102 and a third light-emitting device 103, the electron blocking layers 1323 of the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103 are independently arranged, so that the material of the electron blocking layer 1323 with matching performance can be selected as needed according to the different materials of the light-emitting layer 131.

[0160] Exemplarily, when the light emitting device 100 is a single-layer light emitting device, the structure of the light emitting device 100 (for example, the first light emitting device 101) is, for example, Figure 6 As shown, the light-emitting device 100 includes an anode 11, a hole injection layer 1321, a hole transport layer 1322, an electron blocking layer 1323, a light-emitting layer 131, a hole blocking layer 1333, an electron transport layer 1332, an electron injection layer 1331 and a cathode 12 which are stacked.

[0161] Exemplarily, when the light emitting device 100 is a single-layer light emitting device, and the plurality of light emitting devices 100 include a first light emitting device 101, a second light emitting device 102, and a third light emitting device 103, the structure of the display panel 200 is, for example, Figure 4 As shown, the first light emitting device 101, the second light emitting device 102 and the third light emitting device 103 are arranged along the first direction X. Moreover, the cathode 12 is a common electrode of the first light emitting device 101, the second light emitting device 102 and the third light emitting device 103; the hole injection layer 1321, the hole transport layer 1322, the hole blocking layer 1333, the electron transport layer 1332 and the electron injection layer 1331 are common film layers shared by the first light emitting device 101, the second light emitting device 102 and the third light emitting device 103; the anode 11 is independently arranged, and is respectively the anode 11B of the first light emitting device 101, the anode 11G of the second light emitting device 102 and the anode 11R of the third light emitting device 103. The electron blocking layer 1323 is independently arranged, and is respectively the electron blocking layer 1323B of the first light emitting device 101, the electron blocking layer 1323G of the second light emitting device 102 and the electron blocking layer 1323R of the third light emitting device 103. The light emitting layers 131 are independently provided, namely the light emitting layer 131B of the first light emitting device 101 , the light emitting layer 131G of the second light emitting device 102 , and the light emitting layer 131R of the third light emitting device 103 .

[0162] Exemplarily, when the light emitting device 100 is a stacked light emitting device (for example, including two light emitting units 13), the structure of the light emitting device 100 (for example, the first light emitting device 101) is, for example, Figure 7 and Fig. 9 As shown, the light-emitting device 100 includes a stacked anode 11, a hole transport functional layer 132, a light-emitting layer 131, an electron transport functional layer 133, an electron generating layer 141, a hole generating layer 142, a hole transport functional layer 132, a light-emitting layer 131, an electron transport functional layer 133 and a cathode 12. Among them, the hole transport functional layer 132, the light-emitting layer 131 and the electron transport functional layer 133 located on the side close to the anode 11 constitute a first light-emitting unit 13, and the hole transport functional layer 132, the light-emitting layer 131 and the electron transport functional layer 133 located on the side close to the cathode 12 constitute a second light-emitting unit 13.

[0163] Exemplarily, when the light emitting device 100 is a stacked light emitting device (for example, including two light emitting units 13), and the plurality of light emitting devices 100 include a first light emitting device 101, a second light emitting device 102, and a third light emitting device 103, the structure of the display panel 200 is, for example, Figure 5 and Fig.10As shown, the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103 are arranged along the first direction X. Moreover, the cathode 12 is the common electrode of the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103; each hole transport functional layer 132 of the first light-emitting unit 13 and the second light-emitting unit 13 except the electron blocking layer 1323 and each electron transport functional layer 133 of the first light-emitting unit 13 and the second light-emitting unit 13 are common film layers shared by the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103. The anode 11 of the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103, the electron blocking layer 1323 of the first light-emitting unit 13 and the light-emitting layer 131, the electron blocking layer 1323 of the second light-emitting unit 13 and the light-emitting layer 131 are independently arranged. For the manner of independent arrangement, please refer to the above content, which will not be repeated here.

[0164] For example, in the above-mentioned stacked light-emitting device, Figure 5 , Figure 7 , Fig. 9 and Fig.10 As shown, the hole transport functional layer 132 of the first light emitting unit 13 may include a hole injection layer 1321 , a hole transport layer 1322 and an electron blocking layer 1323 . The hole transport functional layer 132 of the second light emitting unit 13 may include a hole transport layer 1322 and an electron blocking layer 1323 .

[0165] For example, in the above-mentioned stacked light-emitting device, Figure 5 , Figure 7 and Fig. 9 As shown, the electron transport functional layer 133 of the first light emitting unit 13 may include a hole blocking layer 1333. Alternatively, as shown in Fig.10 As shown, the electron transport functional layer 133 of the first light emitting unit 13 may include a hole blocking layer 1333 and an electron transport layer 1332 .

[0166] For example, in the above-mentioned stacked light-emitting device, Figure 5 , Figure 7 and Fig.10 As shown, the electron transport functional layer 133 of the second light emitting unit 13 may include a hole blocking layer 1333, an electron transport layer 1332, and an electron injection layer 1331. Alternatively, as Fig. 9 As shown, the electron transport functional layer 133 of the second light emitting unit 13 may include a hole blocking layer 1333 and an electron transport layer 1332 .

[0167] In the stacked light-emitting device including two light-emitting units 13 , the electron generating layer 141 can inject electrons into the first light-emitting unit 13 , and the hole generating layer 142 can inject holes into the second light-emitting unit 13 .

[0168] In some embodiments, the material of the light emitting layer 131 includes a host material H and a guest material D.

[0169] For example, the host material H may be configured to: transport holes or electrons, and / or to recombined electrons and holes to form excitons and transfer the exciton energy to the guest material D.

[0170] Exemplarily, the guest material D may be configured to: emit photons using the exciton energy transferred from the host material H, and / or to emit photons by forming excitons from recombined electrons and holes.

[0171] In some examples, the guest material D is a fluorescent material that can emit light using singlet excitons; in other examples, the guest material D is a phosphorescent material or a delayed fluorescent material that can emit light using triplet excitons.

[0172] In some examples, the host material H includes more than two materials. For example, the host material H may include a first host material and a second host material, wherein the first host material is a hole-type material and the second host material is an electron-type material.

[0173] Exemplarily, in the case where the plurality of light-emitting devices 100 include the first light-emitting device 101, the host material H of the first light-emitting device 101 may be an anthracene derivative, such as 9,10-di(2-naphthyl)anthracene (ADN) or 2-methyl-9,10-dinaphthylanthracene (MADN); the guest material D of the first light-emitting device 101 may be a pyrene derivative, a fluorene derivative, a perylene derivative, a styrylamine derivative or a metal complex, such as 2,5,8,11-tetra-tert-butylperylene (TBPe), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAVBi), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi) or bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium (FIrpic), etc. The structural formulas of ADN and DPAVBi are as shown below.

[0174]

[0175] Exemplarily, in the case where the plurality of light-emitting devices 100 include a second light-emitting device 102, the main material H of the second light-emitting device 102 may be a coumarin dye, a quinacridone copper derivative, a polycyclic aromatic hydrocarbon, a diamine anthracene derivative or a carbazole derivative, for example, N,N'-dimethylquinacridone (DMQA), N,N'-di-1-naphthyl-N,N'-diphenyl-[9,9'-bianthracene]-10,10'-diamine; N1,N1'-di Phenyl-N1,N1'-dinaphthyl-9,9'-anthracene-1,1'-diamine (BA-NPB), 8-hydroxyquinoline aluminum (Alq3) or 4,4'-di(9-carbazolyl)biphenyl (CPB), etc.; the guest material D of the second light-emitting device 102 can be a metal complex, such as tris(2-phenylpyridine)iridium (Ir(ppy)3) or bis(2-phenylpyridine)iridium acetylacetonate (Ir(ppy)2(acac)), etc. The structural formulas of CPB and Ir(ppy)3 are as shown below.

[0176]

[0177] Exemplarily, in the case where the plurality of light-emitting devices 100 include a third light-emitting device 103, the main material H of the third light-emitting device 103 may be a DCM series material, for example, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminophenylvinyl)-4H-pyran (DCM), 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidine-9-enyl)-4H-pyran (DCJTB), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij ]quinolizine-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (DCJTI) or 2,8-bis(9H-carbazole-9-yl)dibenzo[b,d]thiophene (DCzDBT), etc.; the guest material D of the third light-emitting device 103 can be a metal complex, for example, bis(1-phenyl-isoquinoline)(acetylacetonate)iridium(III) (Ir(piq)2(acac)), platinum(II) octaethylporphyrin (PtOEP) or bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium (Ir(btp)2(acac)), etc. The structural formulas of DCzDBT and Ir(piq)2(acac) are as shown below.

[0178]

[0179] As mentioned in the background, in the field of organic semiconductors, OLED light-emitting devices have the advantages of self-luminescence, low power consumption, bright colors, wide viewing angle, and can be prepared into flexible products. They are gradually replacing liquid crystal displays (LCD) in the field of small and medium-sized displays and have become a mainstream product. They have been successfully applied in lighting systems, communication systems, vehicle display systems, portable electronic devices, and high-definition display devices.

[0180] With the development of OLED light-emitting devices, the requirements for the efficiency, lifespan and other performance of OLED light-emitting devices are getting higher and higher. The efficiency and lifespan of light-emitting devices are related to the device structure and the optimized combination of organic materials in each film layer. Among them, in terms of device structure, the structure of OLED light-emitting devices has developed from the original sandwich structure to a multi-layer device structure. For the description of the multi-layer device structure, please refer to the above content and will not be repeated here.

[0181] Based on the above multi-layer device structure, under the action of the driving voltage, electrons are emitted from the cathode 12, injected through the electron injection layer 1331, and transmitted to the light-emitting layer 131 through the electron transport layer 1332 and the hole blocking layer 1333. Holes are emitted from the anode 11, injected through the hole injection layer 1321, and transmitted to the light-emitting layer 131 through the hole transport layer 1322 and the electron blocking layer 1323. Electrons and holes recombine in the light-emitting layer 131 to generate excitons, which excite radiation transitions to emit light. Among them, according to the different types of electron orbits in the excitons, the excitons can be divided into singlet excitons and triplet excitons, of which singlet excitons account for 25% and triplet excitons account for 75%.

[0182] Since the matching of mobility and energy levels between the functional film layers in the light-emitting device 100, as well as the characteristics of the material itself, will affect the injection and transmission of carriers inside the light-emitting device 100, and / or the formation and quenching of excitons, the interface structure of the OLED light-emitting device will affect the performance of the light-emitting device (such as current density, luminous brightness, luminous efficiency and stability, etc.).

[0183] In some implementations, the consistency of the regions where holes and electrons recombine to form excitons in the first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 is relatively poor, which affects the color matching of the display panel 200 and is prone to color cast problems.

[0184] Based on this, some embodiments of the present disclosure provide a display panel 200, such as Fig.17As shown, the display panel 200 includes a plurality of light-emitting devices 100, and the plurality of light-emitting devices 100 include at least one first light-emitting device 101, at least one second light-emitting device 102, and at least one third light-emitting device 103. The number of light-emitting units 13 included in each light-emitting device 100 is n, and n is a positive integer greater than or equal to 1. The thickness of the light-emitting layer 131 of the Nth light-emitting unit of the third light-emitting device 103 is greater than the thickness of the light-emitting layer 131 of the Nth light-emitting unit of the second light-emitting device 102; the thickness of the light-emitting layer 131 of the Nth light-emitting unit of the second light-emitting device 102 is greater than the thickness of the light-emitting layer 131 of the Nth light-emitting unit of the first light-emitting device 101, wherein N is a positive integer less than or equal to n.

[0185] For example, when n=1, that is, the light emitting device 100 is a single-layer light emitting device, the thickness H of the light emitting layer 131 of the third light emitting device 103 is REML1 , the thickness H of the light emitting layer 131 of the second light emitting device 102 GEML1 and the thickness H of the light emitting layer of the first light emitting device 101 BEML1 Satisfies: H REML1 >H GEML1 >H BEML1 .

[0186] For example, when n=2, that is, the light-emitting device 100 is a stacked light-emitting device including two light-emitting units 13, the light-emitting unit 13 close to the anode 11 can be set as the first light-emitting unit, and the light-emitting unit 13 close to the cathode 12 can be set as the second light-emitting unit. At this time, the thickness H of the light-emitting layer 131 of the first light-emitting unit 13 of the first light-emitting device 101 is BEML1 , the thickness H of the light emitting layer 131 of the first light emitting unit 13 of the second light emitting device 102 GEML1 and the thickness H of the light emitting layer 131 of the first light emitting unit 13 of the third light emitting device 103 REML1 Satisfies: H REML1 >H GEML1 >

[0187] H BEML1 The thickness H of the light emitting layer 131 of the second light emitting unit 13 of the first light emitting device 101 is BEML2 , the thickness H of the light emitting layer 131 of the second light emitting unit 13 of the second light emitting device 102 GEML2 and the thickness H of the light emitting layer 131 of the second light emitting unit 13 of the third light emitting device 103 REML2 Satisfies: H REML2 >H GEML2 >H BEML2 .

[0188] For the description of the stacked light-emitting device when n>2, please refer to the above content and will not be repeated here.

[0189] It should be noted that the thickness mentioned here refers to the dimension of the light emitting layer 131 along the second direction Y.

[0190] It can be understood that the mobility of carriers in the light-emitting layer 131 of the third light-emitting device 103 is greater than the mobility of carriers in the light-emitting layer 131 of the second light-emitting device 102, and the mobility of carriers in the light-emitting layer 131 of the second light-emitting device 102 is greater than the mobility of carriers in the light-emitting layer 131 of the first light-emitting device 101. Through the above-mentioned arrangement, the thickness of the light-emitting layer 131 of the first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 can be matched with the mobility of carriers. In this way, the regions where holes and electrons recombine to form excitons in the first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 can be made relatively consistent, which can alleviate the problem of color deviation.

[0191] In some embodiments, Fig.17 As shown, the thickness H of the light emitting layer 131 of the Nth light emitting unit of the third light emitting device 103 is REMLN , and the thickness H of the light emitting layer 131 of the Nth light emitting unit of the first light emitting device 101 BEMLN The difference between them is the first thickness difference (H REMLN -H BEMLN ); the thickness H of the light emitting layer 131 of the Nth light emitting unit of the second light emitting device 102 GEMLN The thickness H of the light emitting layer 131 of the Nth light emitting unit of the first light emitting device 101 is BEMLN The difference between them is the second thickness difference (H GEMLN -H BEMLN ); the thickness H of the light-emitting layer of the Nth light-emitting unit of the third light-emitting device REMLN , and the thickness H of the light emitting layer 131 of the Nth light emitting unit of the second light emitting device 102 GEMLN The difference between them is the third thickness difference (H REMLN -H GEMLN ); wherein the first thickness difference (H REMLN -H BEMLN ) and the second thickness difference (H GEMLN -H BEMLN ) is greater than or equal to 1.5 and less than or equal to 2. The third thickness difference (H REMLN -H GEMLN ) and the second thickness difference (H GEMLN -H BEMLN ) is greater than or equal to 1 and less than or equal to 1.5. That is, 1.5≤(HREMLN -H BEMLN ) / (H GEMLN -H BEMLN )≤2, and 1≤(H REMLN -H GEMLN ) / (H GEMLN -H BEMLN )≤1.5.

[0192] By such an arrangement, the thickness of the light-emitting layer 131 of the second light-emitting device 102 and the thickness of the light-emitting layer 131 of the third light-emitting device 103 can be made relatively small. Thus, the driving voltage of the second light-emitting device 102 and the third light-emitting device 103 can be made relatively low, thereby reducing the driving voltage of the display panel 200.

[0193] Exemplarily, the first thickness difference (H REMLN -H BEMLN ) and the second thickness difference (H GEMLN -H BEMLN ) can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, etc.

[0194] Exemplarily, the third thickness difference (H REMLN -H GEMLN ) and the second thickness difference (H GEMLN -H BEMLN ) can be 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0195] In some embodiments, Fig.17 As shown, the light-emitting unit 13 further includes a first type functional layer 132 disposed on the side of the light-emitting layer 131 close to the anode 11; the first type functional layer 132 includes a first sub-functional layer 1323 in contact with the light-emitting layer 131; the thickness H of the first sub-functional layer 132 of the Nth light-emitting unit of the third light-emitting device 103 is R1GN , and the thickness H of the first sub-functional layer 132 of the Nth light-emitting unit of the first light-emitting device 101 B1GN The difference between them is the fourth thickness difference (H R1GN -H B1GN ); the thickness H of the first sub-functional layer 132 of the Nth light-emitting unit of the second light-emitting device 102 G1GN The thickness H of the first sub-functional layer 132 of the Nth light-emitting unit of the first light-emitting device 101 is B1GN The difference between them is the fifth thickness difference (H G1GN -H B1GN ). The fourth thickness difference (H R1GN -H B1GN ) and the fifth thickness difference (H G1GN -H B1GN) is greater than or equal to 1.1 and less than or equal to 1.5. That is, 1.1≤(H R1GN -H B1GN ) / (H G1GN -H B1GN )≤1.5.

[0196] Exemplarily, the first functional layer 132 is a hole transport functional layer; and the first sub-functional layer 1323 is an electron blocking layer 1323 .

[0197] It can be understood that when the thickness of the light-emitting layer 131 of the second light-emitting device 102 and the thickness of the light-emitting layer 131 of the third light-emitting device 103 are relatively small, through the above-mentioned setting, the color coordinates of the first light-emitting device 101, the second light-emitting device 102 and the third light-emitting device 103 can be adjusted by adjusting the thickness of the first sub-functional layer 1323, so that the display panel 200 has a high color gamut display effect.

[0198] Exemplarily, the fourth thickness difference (H R1GN -H B1GN ) and the fifth thickness difference (H G1GN -H B1GN ) can be 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0199] In some embodiments, Fig.17 As shown, the light-emitting unit 13 also includes a second type functional layer 133 arranged on the side of the light-emitting layer 131 close to the cathode 12; the ratio between the thickness of the first type functional layer 132 and the thickness of the second type functional layer 133 is greater than or equal to 1 and less than or equal to 5.

[0200] Exemplarily, the first type of functional layer 132 is a hole transport functional layer; the second type of functional layer 133 is an electron transport functional layer. It should be noted that the thickness of the first type of functional layer 132 can be the sum of the thickness of the hole transport layer 1322 and the hole injection layer 1321, or the sum of the thickness of the hole transport layer 1322, the hole injection layer 1321 and the electron blocking layer 1323, which is not limited here. Correspondingly, the thickness of the second type of functional layer 133 can be the sum of the thickness of the electron transport layer 1332 and the electron injection layer 1331, or the sum of the thickness of the electron transport layer 1332, the electron injection layer 1331 and the hole blocking layer 1333, which is not limited here.

[0201] It can be understood that, since the hole mobility of the material of the hole transport functional layer 132 is relatively high, by setting the ratio between the thickness of the first type functional layer 132 and the thickness of the second type functional layer 133 to be greater than or equal to 1 and less than or equal to 5, the thickness of the hole transport functional layer can be made relatively large, so that the transmission of carriers can be relatively more balanced, and the area where holes and electrons recombine to form excitons can be relatively far away from the first sub-functional layer 1323 (for example, the electron blocking layer 1323), so that the electrons and excitons have relatively less influence on the first sub-functional layer 1323, and the life of the light-emitting device 100 can be improved. At the same time, by such a setting, the light emitted by the light-emitting device 100 can meet the set requirements.

[0202] For example, the ratio of the thickness of the first type functional layer 132 to the thickness of the second type functional layer 133 may be 1, 2, 3, 4 or 5, etc.

[0203] In some embodiments, the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 is BD , greater than or equal to 650, and less than or equal to 1300. That is, 650≤M BD ≤1300.

[0204] By setting in this way, the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 can be BD Relatively high, the Tg of the guest material BD can be relatively high, the thermal stability of the guest material BD can be improved, the film-forming property of the guest material BD can be improved, the film stability of the light-emitting layer 131 of the first light-emitting device 101 can be relatively high, and the life of the light-emitting device 100 can be improved.

[0205] For example, the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 is BD It can be 650, 658, 757, 822, 896, 940, 980, 1019 or 1300, etc.

[0206] In some embodiments, the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 is GD , greater than or equal to 700, and less than or equal to 1400. That is, 700≤M GD ≤1400.

[0207] By setting in this way, the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 can be GDIt is relatively high, which can make the Tg of the guest material GD relatively high, improve the thermal stability of the guest material GD, improve the film-forming property of the guest material GD, make the film stability of the light-emitting layer 131 of the second light-emitting device 102 relatively high, and improve the life of the light-emitting device 100.

[0208] For example, the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 is GD It can be 700, 715, 716, 797, 880, 1089, 1160, 1300 or 1400, etc.

[0209] In some embodiments, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 is RD , greater than or equal to 700, and less than or equal to 1500. That is, 700≤M BD ≤1500.

[0210] By setting in this way, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 can be RD Relatively high, the Tg of the guest material RD can be relatively high, the thermal stability of the guest material RD can be improved, the film-forming property of the guest material RD can be improved, the film stability of the light-emitting layer 131 of the third light-emitting device 103 can be relatively high, and the life of the light-emitting device 100 can be improved.

[0211] For example, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 is RD It can be 700, 741, 793, 1078, 1276, 1400 or 1500, etc.

[0212] In some embodiments, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 is RD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The absolute value of the difference between |M RD -M BD |, less than or equal to 600. That is, |M RD -M BD |≤600.

[0213] For example, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 is RD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The absolute value of the difference between |M RD -M BD|It can be 0, 100, 200, 300, 400, 500 or 600, etc.

[0214] In some embodiments, the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 is GD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The absolute value of the difference between |M GD -M BD |, less than or equal to 500. That is, |M GD -M BD |≤500.

[0215] For example, the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 is GD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The absolute value of the difference between |M GD -M BD |It can be 0, 100, 200, 300, 400 or 500 etc.

[0216] In some embodiments, the relative molecular weight M of the guest material RD of the light-emitting layer 131 of the third light-emitting device 103 is RD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The difference between RD -M BD ) is the first relative molecular weight difference; the relative molecular weight M of the guest material GD of the light-emitting layer 131 of the second light-emitting device 102 GD , and the relative molecular weight M of the guest material BD of the light-emitting layer 131 of the first light-emitting device 101 BD The difference between GD -M BD ) is the second relative molecular weight difference. The ratio between the absolute value of the first relative molecular weight difference and the absolute value of the second relative molecular weight difference is greater than or equal to 0.5 and less than or equal to 6. That is:

[0217]

[0218] For example, the ratio of the absolute value of the first relative molecular weight difference to the absolute value of the second relative molecular weight difference may be 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 or 6.0.

[0219] In some embodiments, the optical path of the light in the light-emitting layer 131 of the light-emitting unit 13 near the anode 11 of the first light-emitting device 101 and the first type functional layer 132 is the first optical path D1; the optical path of the light in the light-emitting layer 131 of the light-emitting unit 13 near the anode 11 of the second light-emitting device 102 and the first type functional layer 132 is the second optical path D2; the optical path of the light in the light-emitting layer 131 of the light-emitting unit 13 near the anode 11 of the third light-emitting device 103 and the first type functional layer 132 is the third optical path D3; wherein the ratio between the third optical path D3 and the second optical path D2 is greater than or equal to 1.1 and less than or equal to 1.25. That is: 1.1≤D3 / D2≤1.25. The ratio between the third optical path D3 and the first optical path D1 is greater than or equal to 1.25 and less than or equal to 1.45. That is: 1.25≤D3 / D1≤1.45. The ratio of the second optical path D2 to the first optical path D1 is greater than or equal to 1.05 and less than or equal to 1.25, that is, 1.05≤D2 / D1≤1.25.

[0220] In the relevant technology, the optical path can be understood as the distance that light travels in a vacuum in the same time. Under the condition of the same propagation time or the same phase change, the distance that light travels in the medium is converted into the corresponding distance that light travels in a vacuum. Numerically, the optical path is equal to the refractive index of the medium multiplied by the distance that light travels in the medium.

[0221] Exemplarily, in the case where the first functional layer 132 of the light-emitting unit 13 close to the anode 11 of the light-emitting device 100 (for example, the first light-emitting device 101, the second light-emitting device 102, or the third light-emitting device 103) includes a hole injection layer 1321, a hole transport layer 1322, and an electron blocking layer 1323, the light-emitting layer 131 of the light-emitting unit 13 close to the anode 11 of the light-emitting device 101 and the optical path D in the first functional layer 132 can be calculated by the following formula:

[0222] D1=d1×n1+d2×n2+d3×n3+d4×n4

[0223] Among them, d1, d2, d3, and d4 are the thicknesses of the hole injection layer 1321, the hole transport layer 1322, the electron blocking layer 1323, and the light-emitting layer 131, respectively; n1, n2, n3, and n4 are the refractive indices of the material of the hole injection layer 1321, the material of the hole transport layer 1322, the material of the electron blocking layer 1323, and the material of the light-emitting layer 131, respectively.

[0224] Regarding the case where the first type functional layer 132 of the light-emitting unit 13 close to the anode 11 of the light-emitting device 100 includes a hole injection layer 1321 and a hole transport layer 1322, or a hole transport layer 1322 and an electron blocking layer 1323, etc., reference may be made to the above description and no further details are given here.

[0225] It can be understood that when 1.1≤D3 / D2≤1.25, 1.25≤D3 / D1≤1.45, and 1.05≤D2 / D1≤1.25, the light extraction efficiency of the third light-emitting device 103, the second light-emitting device 102 and the first light-emitting device 101 can be made relatively high. In this way, the external quantum efficiency of the third light-emitting device 103, the second light-emitting device 102 and the first light-emitting device 101 can be improved, thereby improving the efficiency of the display panel 200.

[0226] Exemplarily, the ratio between the third optical path D3 and the second optical path D2 may be 1.10, 1.15, 1.20 or 1.25, etc.

[0227] Exemplarily, the ratio between the third optical path D3 and the first optical path D1 may be 1.25, 1.30, 1.35, 1.40 or 1.45, etc.

[0228] For example, the ratio of the second optical path D2 to the first optical path D1 may be 1.05, 1.10, 1.15, 1.20 or 1.25, etc.

[0229] In some embodiments, Fig.17 As shown, the light emitting device 100 includes a first light emitting unit and a second light emitting unit; the first light emitting unit is closer to the anode 11 than the second light emitting unit; the thickness H of the light emitting layer 131 of the first light emitting unit EML1 , and the thickness H of the light-emitting layer 131 of the second light-emitting unit EML2 The ratio between is greater than or equal to 0.8 and less than or equal to 1.5. That is: 0.8≤H EML1 / H EML2 ≤1.5.

[0230] It is understandable that when 0.8≤H EML1 / H EML2 ≤1.5, the thickness H of the light-emitting layer 131 of the first light-emitting unit EML1 , and the thickness H of the light emitting layer 131 of the second light emitting unit EML2 Relatively consistent, in this way, firstly, the probability of color deviation can be reduced, so that the color purity of the light-emitting device 100 can be improved; secondly, the efficiency of the light-emitting device 100 can be improved, so that the stacked light-emitting device can achieve the expected efficiency.

[0231] For example, the thickness H of the light-emitting layer 131 of the first light-emitting unit is EML1 , and the thickness H of the light-emitting layer 131 of the second light-emitting unit EML2 The ratio between them can be 0.8, 1.0, 1.2, 1.4 or 1.5, etc.

[0232] The light emitting device 101 may be any one of the first light emitting device 101 , the second light emitting device 102 and the third light emitting device 103 , which is not limited here.

[0233] In some embodiments, Fig.17 As shown, in the case where the light-emitting unit 13 includes a first type functional layer 132 and a second type functional layer 133, the first type functional layer 132 also includes a second sub-functional layer 1322 and a fourth sub-functional layer 1321, and the fourth sub-functional layer 1321, the second sub-functional layer 1322 and the first sub-functional layer 1323 are arranged in sequence in a direction away from the anode 11; the second type functional layer 133 includes a third sub-functional layer 1333, a fifth sub-functional layer 1332 and a sixth sub-functional layer 1331; the sixth sub-functional layer 1331, the fifth sub-functional layer 1332 and the third sub-functional layer 1333 are arranged in sequence in a direction away from the cathode 12; wherein the thickness H of the second sub-functional layer 1322 of the second light-emitting unit 13 is 2G2 The thickness H of the fifth sub-functional layer 1332 is 5G2 The sum of the first thickness and (H 2G2 +H 5G2 ), and the thickness H of the second sub-functional layer 1322 of the first light-emitting unit 13 2G1 The thickness H of the fifth sub-functional layer 1332 is 5G1 The sum of the second thickness and (H 2G1 +H 5G1 ); the first thickness and (H 2G2 +H 5G2 ) and the second thickness and (H 2G1 +H 5G1 ) is greater than or equal to 2 and less than or equal to 4. That is, 2≤(H 2G2 +H 5G2 ) / (H 2G1 +H 5G1 )≤4.

[0234] Exemplarily, the first sub-functional layer is the electron blocking layer 1323; the second sub-functional layer is the hole transport layer 1322; the fourth sub-functional layer is the hole injection layer 1321; the third sub-functional layer is the hole blocking layer 1333; the fifth sub-functional layer is the electron transport layer 1332; and the sixth sub-functional layer is the electron injection layer 1333.

[0235] It can be understood that when the ratio between the first thickness sum and the second thickness sum is greater than or equal to 2 and less than or equal to 4, the thickness of the second light-emitting unit is relatively larger than that of the first light-emitting unit, thereby improving the light extraction efficiency of the stacked light-emitting device 100.

[0236] For example, the ratio between the first thickness and the second thickness may be 2.0, 2.5, 3.0, 3.5 or 4.0, etc.

[0237] The light emitting device 101 may be any one of the first light emitting device 101 , the second light emitting device 102 and the third light emitting device 103 , which is not limited here.

[0238] In some embodiments, Fig.17 As shown, the thickness H of the first sub-functional layer 1323 of the second light-emitting unit 1G2 The thickness H of the second sub-functional layer 1322 2G2 The sum of the third thickness and (H 1G2 +H 2G2 ), the thickness H of the first sub-functional layer 1323 of the first light-emitting unit 1G1 The thickness H of the second sub-functional layer 1322 2G1 The sum of the fourth thickness and (H 1G1

[0239] +H 2G1 ); the third thickness and (H 1G2 +H 2G2 ) and the fourth thickness and (H 1G1 +H 2G1 ) is greater than or equal to 2 and less than or equal to 5. That is, 2≤(H 1G2 +H 2G2 ) / (H 1G1 +H 2G1 )≤5.

[0240] It can be understood that when the ratio between the third thickness sum and the fourth thickness sum is greater than or equal to 2 and less than or equal to 5, the thickness of the second light-emitting unit is relatively larger than that of the first light-emitting unit, thereby improving the light extraction efficiency of the stacked light-emitting device 100.

[0241] Exemplarily, the ratio between the third thickness sum and the fourth thickness sum may be 2.0, 2.5, 3.0, 3.5, 4.0 or 5.0, etc.

[0242] The light emitting device 101 may be any one of the first light emitting device 101 , the second light emitting device 102 and the third light emitting device 103 , which is not limited here.

[0243] In some embodiments, Fig.17 As shown, the thickness H of the third sub-functional layer 1333 of the second light-emitting unit 3G2 The thickness H of the fifth sub-functional layer 1332 is 5G2 The sum of the fifth thickness and (H 3G2 +H 5G2), the thickness H of the third sub-functional layer 1333 of the first light-emitting unit 3G1 The thickness H of the fifth sub-functional layer 1332 is 5G1 The sum of the sixth thickness and (H 3G1

[0244] +H 5G1 ). Fifth thickness (H 3G2 +H 5G2 ) and the sixth thickness and (H 3G1 +H 5G1 ) is greater than or equal to 1.5 and less than or equal to 3. That is, 1.5≤(H 3G2 +H 5G2 ) / (H 3G1 +H 5G1 )≤3.

[0245] It can be understood that when the ratio between the fifth thickness sum and the sixth thickness sum is greater than or equal to 1.5 and less than or equal to 3, the thickness of the second light-emitting unit is relatively larger than that of the first light-emitting unit, thereby improving the light extraction efficiency of the stacked light-emitting device 100.

[0246] Exemplarily, the ratio between the fifth thickness sum and the sixth thickness sum may be 1.5, 2.0, 2.2, 2.5 or 3.0, etc.

[0247] The light emitting device 101 may be any one of the first light emitting device 101 , the second light emitting device 102 and the third light emitting device 103 , which is not limited here.

[0248] In some implementations, when the display panel 200 includes the first light emitting device 101 , the second light emitting device 102 , and the third light emitting device 103 , the lifetime of the first light emitting device 101 is relatively short.

[0249] In other implementations, during the light emission process of the light emitting device 100, the region where holes and electrons recombine to form excitons (hereinafter referred to as the exciton recombination region for convenience of description) is located at the interface between the electron blocking layer 1323 and the light emitting layer 131. In some cases, during the light emission process of the first light emitting device 101, the exciton intensity at each position along the second direction Y in the light emitting layer 131 is, for example, Fig.11 As shown by Fig.11It can be seen that, compared with the middle position of the light-emitting layer 131 and the position of the light-emitting layer 131 close to the electron transport functional layer 133, the exciton intensity is relatively high on the side of the light-emitting layer 131 close to the electron blocking layer 1323. This is because the transmission rate of electrons is greater than the transmission rate of holes, resulting in the exciton recombination region being located on the side of the light-emitting layer 131 close to the electron blocking layer 1323. In this case, electrons and high-energy excitons will accumulate on the material of the electron blocking layer 1323, resulting in degradation of the material of the electron blocking layer 1323, affecting the performance (e.g., lifespan) of the light-emitting device, and further affecting the overall lifespan of the display panel 200. Therefore, improving the lifespan of the light-emitting device 100 (especially the first light-emitting device 101) is of great significance to improving the overall lifespan of the display panel 200.

[0250] Based on this, some embodiments of the present disclosure provide a light-emitting device 100, wherein the light-emitting unit 13 includes a first type of functional layer arranged on the side of the light-emitting layer 131 close to the anode 11; the first type of functional layer includes a first sub-functional layer and a second sub-functional layer; the material of the first sub-functional layer includes a first functional material, and the material of the second sub-functional layer includes a second functional material; wherein the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%.

[0251] It can be understood that the first type of functional layer is the hole transport functional layer 132. The first sub-functional layer can be one of the hole injection layer 1321, the hole transport layer 1322 and the electron blocking layer 1323, and the second sub-functional layer can be the other of the hole injection layer 1321, the hole transport layer 1322 and the electron blocking layer 1323.

[0252] Exemplarily, the first sub-functional layer is the electron blocking layer 1323 , and the first functional material is the material of the electron blocking layer 1323 ; the second sub-functional layer is the hole transport layer 1322 , and the second functional material is the material of the hole transport layer 1322 .

[0253] In the related art, the density of states (DOS) can be defined by the number of electronic states allowed to be occupied in specific energy levels such as the highest occupied molecular orbital (HOMO) energy level and the lowest unoccupied molecular orbital (LUMO) energy level.

[0254] The state density can be obtained by simulation and calculation using molecular dynamics and quantum mechanics. The specific process is as follows: Since a molecule has different conformations, when the simulation software calculates, it first simulates hundreds to thousands of molecules (for example, 500 molecules) through molecular dynamics, optimizes the molecular conformation, and makes the optimized molecular conformation conform to the Boltzman distribution. Then, a cell is established, and the geometric configurations of different conformations are filled into the cell according to different weights, for example, Fig.12 Then, the highest occupied molecular orbital (HOMO) energy level and / or the lowest unoccupied molecular orbital (LUMO) energy level are calculated by quantum mechanics, and the calculated highest occupied molecular orbital energy level and / or the lowest unoccupied molecular orbital energy level conform to the Gaussian distribution, thereby obtaining the state density.

[0255] It can be understood that the greater the overlap of the HOMO state density of the two materials, the more conducive it is to the transmission of holes between the two materials. When the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%, the HOMO state density of the first functional material (for example, the material of the electron blocking layer 1323) and the HOMO state density of the second functional material (for example, the material of the hole transport layer 1322) overlap with each other, so that the hole transmission rate between the first sub-functional layer (for example, the electron blocking layer 1323) and the second sub-functional layer (for example, the hole transport layer 1322) can be increased, and the hole transmission effect of the first type of functional layer (i.e., the hole transport functional layer 132) is improved. In this way, the holes and electrons can be relatively more balanced. On the one hand, the exciton recombination area can be relatively far away from the electron blocking layer 1323, reducing the accumulation of electrons and excitons on the material of the electron blocking layer 1323, slowing down the degradation of the material of the electron blocking layer 1323, improving the stability of the material of the electron blocking layer 1323, and improving the life of the light-emitting device 100; on the other hand, the yield of excitons can be increased, the energy utilization rate can be improved, and the efficiency of the light-emitting device 100 can be improved.

[0256] In some examples, when the first sub-functional layer is the electron blocking layer 1323 and the second sub-functional layer is the hole transport layer 1322, the state density distribution diagram of the material of the electron blocking layer 1323 (i.e., the first functional material) and the material of the hole transport layer 1322 (i.e., the second functional material) is as shown in FIG. Fig.13 As shown in the figure, the state density of the energy level on the left side in the range of -4.4eV to -5.0eV is the HOMO state density, and the state density of the energy level on the right side in the range of -1.5eV to -0.7eV is the LUMO state density. Fig.13It can be seen that the HOMO state density of the material of the electron blocking layer 1323 overlaps with the HOMO state density of the material of the hole transporting layer 1322 in the energy level range of -4.4 eV to -4.85 eV, and has a high overlap rate.

[0257] Exemplarily, the overlap rate of the HOMO state density of the first functional material (e.g., the material of the electron blocking layer 1323) and the HOMO state density of the second functional material (e.g., the material of the hole transport layer 1322) can be 1%, 5%, 10%, 30%, 50%, 70% or 90%, etc.

[0258] In some embodiments, the structural formula of the second functional material is as follows:

[0259]

[0260] It should be noted that (HTL) in the above structural formula is a synonym for the structural formula and is not a part of the structural formula.

[0261] The second functional material is a material having a hole transport function. Based on the above structure, the second sub-functional layer can be a hole transport layer, or can also be a hole injection layer.

[0262] In some embodiments, the first sub-functional layer is in contact with the light-emitting layer 131 ; and an overlap ratio of the HOMO state density of the first functional material and the HOMO state density of the host material is greater than 0% and less than or equal to 90%.

[0263] The above-mentioned first sub-functional layer is in contact with the light-emitting layer 131, that is, the first sub-functional layer is the layer of the first type of functional layer that is closest to the light-emitting layer 131 and in contact with the light-emitting layer 131. For example, the first sub-functional layer can be one of the hole injection layer 1321, the hole transport layer 1322 and the electron blocking layer 1323.

[0264] Exemplarily, the first sub-functional layer is the electron blocking layer 1323 , and the first functional material is the material of the electron blocking layer 1323 .

[0265] As mentioned above, the greater the overlap of the HOMO state density of the two materials, the more conducive it is to the transmission of holes between the two materials, and the main material is the main material that performs the hole transport function in the light-emitting layer 131. When the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the main material is greater than 0% and less than or equal to 90%, the HOMO state density of the first functional material (for example, the material of the electron blocking layer 1323) and the HOMO state density of the main material overlap with each other, so that the hole transmission rate between the first functional material (for example, the material of the electron blocking layer 1323) and the main material can be increased, and the hole transmission effect from the first type of functional layer (i.e., the hole transport functional layer 132) to the light-emitting layer 131 can be improved. In this way, the holes and electrons can be relatively more balanced. On the one hand, the exciton recombination area can be relatively far away from the electron blocking layer 1323, reducing the accumulation of electrons and excitons on the material of the electron blocking layer 1323, slowing down the degradation of the material of the electron blocking layer 1323, improving the stability of the material of the electron blocking layer 1323, and improving the life of the light-emitting device 100; on the other hand, the yield of excitons can be increased, the energy utilization rate can be improved, and the efficiency of the light-emitting device 100 can be improved.

[0266] Exemplarily, the overlap rate of the HOMO state density of the first functional material (eg, the material of the electron blocking layer 1323) and the HOMO state density of the host material may be 2%, 8%, 10%, 30%, 50%, 75% or 90%, etc.

[0267] In some examples, the HOMO state density of the material of the electron blocking layer 1323 satisfies at least one of the following conditions (i) and (ii):

[0268] (i) The overlap ratio of the HOMO state density of the material of the electron blocking layer 1323 and the HOMO state density of the material of the hole transporting layer 1322 is greater than 0% and less than or equal to 90%.

[0269] (ii) The overlap ratio of the HOMO state density of the material of the electron blocking layer 1323 and the HOMO state density of the host material is greater than 0% and less than or equal to 90%.

[0270] In some embodiments, the absolute value of the difference between the electron reorganization energy λe(H) and the hole reorganization energy λh(H) of the host material H is less than or equal to 0.1 eV. In other words, the electron reorganization energy λe(H) of the host material H and the hole reorganization energy λh(H) of the host material H satisfy: |λe(H)-λh(H)|≤0.1 eV.

[0271] In the related art, hole reorganization energy can be used to characterize the hole mobility of a material, and electron reorganization energy can be used to characterize the electron mobility of a material.

[0272] It can be understood that when |λe(H)-λh(H)|≤0.1eV, the difference between the hole mobility of the main material and the electron mobility of the main material is relatively small, so that the migration rate of holes in the main material and the migration rate of electrons in the main material can be relatively consistent; in this way, the electrons and holes can be relatively more balanced. As mentioned above, the degradation of the material of the electron blocking layer 1323 can be slowed down, and the life of the light-emitting device 100 can be improved; at the same time, the yield of excitons can be increased, so that the efficiency of the light-emitting device 100 can be improved.

[0273] In some examples, the electron reorganization energy λe(H) of the host material H is greater than the hole reorganization energy λh(H) of the host material H, and the two satisfy: λe(H)-λh(H)≤0.1eV. For example, the difference between the electron reorganization energy λe(H) of the host material H and the hole reorganization energy λh(H) of the host material H can be 0eV, 0.2eV, 0.4eV, 0.6eV, 0.8eV or 1.0eV, etc.

[0274] In other examples, the hole reorganization energy λh(H) of the host material H is greater than the electron reorganization energy λe(H) of the host material H, and the two satisfy: λh(H)-λe(H)≤0.1eV. For example, the difference between the hole reorganization energy λh(H) of the host material H and the electron reorganization energy λe(H) of the host material H can be 0eV, 0.15eV, 0.4eV, 0.6eV, 0.85eV or 1.0eV, etc.

[0275] In some embodiments, the hole mobility of the host material is greater than the electron mobility of the host material.

[0276] It can be understood that when the hole mobility of the main material is greater than the electron mobility of the main material, the exciton recombination area can be relatively far away from the electron blocking layer 1323, reducing the accumulation of carriers (electrons or holes) and excitons on the material of the electron blocking layer 1323, which can slow down the degradation of the material of the electron blocking layer 1323, improve the stability of the material of the electron blocking layer 1323, and increase the life of the light-emitting device 100.

[0277] In some implementations, the guest material of the light-emitting device 100 (for example, the first light-emitting device 101) is a fluorescent material. Compared with phosphorescent materials that can emit light using triplet excitons through spin-orbit coupling, fluorescent materials do not have spin-orbit coupling, so that they can only emit fluorescence by using singlet excitons to deactivate radiation as the ground state, and cannot use the energy of triplet excitons with a high probability of generation for light emission. Therefore, the internal quantum efficiency (IQE) of the light-emitting device 100 with fluorescent materials as guest materials reaches its theoretical limit of 25% at most, which is lower than the internal quantum efficiency of the light-emitting device 100 with phosphorescent materials as guest materials (which can reach 100%), resulting in the relatively low efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) with fluorescent materials as guest materials.

[0278] In order to increase the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) using fluorescent materials as guest materials, the triplet-triplet exciton annihilation (TTA) effect can be used to utilize triplet excitons to emit light, thereby increasing the luminous efficiency of the fluorescent material. One form of the triplet-triplet exciton annihilation (TTA) effect is the triplet-triplet fusion (TTF) effect, the principle of which is: singlet excitons are generated by the collision and fusion of two triplet excitons, thereby increasing the fluorescence emission, and the process is as follows: Fig.14 As shown. Fig.14 It can be seen that after the collision and fusion of two triplet excitons, S n and S0, where S n Singlet exciton S1 can be generated by vibration relaxation, and the process of S1 radiatively transitioning to S0 can realize fluorescent luminescence. The generation probability of the singlet exciton S1 is, for example, five triplet excitons generate one singlet exciton S1. It can be seen that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) using fluorescent material as the guest material can be increased through the TTF effect.

[0279] However, during the TTF process, when triplet excitons collide with triplet excitons, high-energy intermediates are generated. When the energy of the intermediates is higher than the bond dissociation energy of the host material and / or the guest material, it may cause degradation of the host material and / or the guest material. Here, bond dissociation energy (BDE) can be understood as the energy required to break a specific chemical bond. Generally speaking, the higher the bond dissociation energy, the more stable the molecule, and correspondingly, the stability of the material is relatively high.

[0280] In some embodiments, at least one of the host material, the guest material, and the first functional material is a deuterated material.

[0281] It should be noted that a deuterated material refers to a material in which at least one hydrogen atom in its structure is replaced by a deuterium atom. In other words, the structure of the deuterated material contains at least one deuterium atom.

[0282] It is understandable that hydrogen atoms are common elements in OLED organic materials, deuterium is an isotope of hydrogen, and the atomic weight of deuterium is twice that of hydrogen. When the hydrogen in the compound molecule is replaced by deuterium, the chemical properties of the compound remain almost unchanged. Moreover, compared to the carbon-hydrogen bond, the carbon-deuterium bond has a shorter bond length, a higher bond dissociation energy, and a lower vibration energy, which can shorten the bond length, increase the bond dissociation energy, and improve the molecular stability. When the hydrogen atoms in the material molecules are replaced by deuterium atoms, the physical and chemical properties of the material will change. In order to more clearly illustrate the effect of deuteration of the material on the bond dissociation energy, through Fig.15 Exemplary schematic diagram of the change in bond dissociation energy before and after deuteration of a material. Fig.15 It can be seen that when the hydrogen atoms in the molecule are replaced by deuterium atoms, the zero-point vibration energy of the compound can be reduced (by V 0H Reduce to V 0D ), increasing the bond dissociation energy of the compound and improving its stability.

[0283] In addition, when the material contains relatively more deuterium atoms, the energy required for the material to undergo side reactions is also relatively high. Therefore, deuteration can make the probability of the material undergoing side reactions relatively low, thereby improving the stability of the material.

[0284] In some examples, the host material is a deuterated material.

[0285] By such a configuration, compared with the case where the main material does not contain deuterium atoms, firstly, the bond dissociation energy of the main material can be increased, so that the bond dissociation energy of the main material is higher than the energy of the intermediate of the TTF effect, so that the probability of degradation of the main material under the influence of the energy of the intermediate is relatively lower, and at the same time, the probability of side reactions of the main material can be reduced, the stability of the main material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. Second, the energy of the intermediate of the TTF effect can be reduced, the difference between the bond dissociation energy of the main material and the energy of the intermediate of the TTF effect can be increased, the probability of degradation of the main material can be reduced, and the stability of the main material and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. Third, the molecular vibration of the main material can be reduced, the energy loss caused by the molecular vibration of the main material can be reduced, and the quantum efficiency loss caused by the molecular vibration of the main material can be reduced, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0286] In some examples, the guest material is a deuterated material.

[0287] By such a configuration, compared with the case where the guest material does not contain deuterium atoms, firstly, the bond dissociation energy of the guest material can be increased, so that the bond dissociation energy of the guest material is higher than the energy of the intermediate of the TTF effect, so that the probability of degradation of the guest material under the influence of the intermediate energy is relatively lower, and at the same time, the probability of side reactions of the guest material can be reduced, the stability of the guest material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. Secondly, the molecular vibration of the guest material can be reduced, the energy loss caused by the molecular vibration of the guest material can be reduced, and the quantum efficiency loss caused by the molecular vibration of the guest material can be reduced, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. Thirdly, when the molecular vibration of the guest material is reduced, the emission spectrum of the guest material can be narrowed, so that the color purity of the light-emitting device 100 (for example, the first light-emitting device 101) is relatively high.

[0288] In some examples, the first functional material is a deuterated material. The first functional material is, for example, the material of the electron blocking layer 1323 .

[0289] Through such a configuration, compared with the case where the first functional material does not contain deuterium atoms, the bond dissociation energy of the first functional material can be increased, and at the same time the probability of side reactions in the first functional material can be reduced, thereby improving the electrical stability of the first functional material, improving the electronic resistance of the first functional material, and slowing down the degradation of the first functional material caused by electrons and excitons, thereby improving the stability of the first functional material and improving the life of the light-emitting device 100 (for example, the first light-emitting device 101).

[0290] In some examples, the host material, the guest material, and the first functional material are all deuterated materials.

[0291] Regarding the beneficial effects that can be achieved when the main material, the guest material and the first functional material are all deuterated materials, please refer to the previous description and will not be repeated here.

[0292] In some embodiments, the dipole moment of the first functional material is greater than 0D.

[0293] It is understandable that when the molecule is asymmetric, the molecule is relatively more stable, and the higher the asymmetry of the molecule, the higher the stability of the molecule. When the dipole moment of the first functional material is greater than 0D, the molecule of the first functional material has an asymmetric structure, so that the stability of the first functional material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0294] For example, the dipole moment of the first functional material may be 0.05D, 0.10D, 0.20D, 0.30D or 0.40D, etc.

[0295] In some examples, the dipole moment of the host material is greater than 0, for example, the dipole moment of the host material may be 0.06D, 0.10D, 0.20D, 0.25D or 0.30D, etc. In this way, the stability of the host material can be improved, so that the life of the light emitting device 100 (for example, the first light emitting device 101) is improved.

[0296] In some examples, the dipole moment of the guest material is greater than 0, for example, the dipole moment of the guest material may be 0.04D, 0.08D, 0.10D, 0.20D or 0.25D, etc. In this way, the stability of the guest material can be improved, and the life of the light emitting device 100 (for example, the first light emitting device 101) can be improved.

[0297] In the related art, since a material molecule contains multiple chemical bonds, each chemical bond has a corresponding bond dissociation energy (BDE). Among them, the lowest bond dissociation energy refers to the energy required for bond breaking at the most easily broken part of the molecule. Taking the methane molecule as an example, its molecule contains four carbon-hydrogen bonds, and the bond dissociation energy corresponding to each carbon-hydrogen bond is different. Among them, the first hydrogen atom in the methane molecule is the easiest to lose, and the energy required to lose the first hydrogen atom is the lowest bond dissociation energy of methane.

[0298] In some embodiments, the lowest of the bond dissociation energies of the first functional material in the ground state is greater than or equal to 2.40 eV.

[0299] It is understood that the lowest bond dissociation energy of the first functional material in the ground state can be used to characterize the molecular stability of the first functional material. When the lowest bond dissociation energy of the first functional material in the ground state is greater than or equal to 2.40 eV, the molecular stability of the first functional material is relatively high, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0300] For example, the lowest bond dissociation energy of the first functional material in the ground state may be 2.40 eV, 2.80 eV, 3.50 eV, 4.00 eV, 4.50 eV, or 5.0 eV.

[0301] In some embodiments, the lowest of the bond dissociation energies of the first functional material in an anionic state is greater than or equal to 1.0 eV.

[0302] It can be understood that the lowest bond dissociation energy of the first functional material in the anionic state can be used to characterize the electron resistance of the first functional material. When the lowest bond dissociation energy of the first functional material in the anionic state is greater than or equal to 1.0 eV, the electron resistance of the first functional material is relatively high, so that the degradation of the first functional material caused by the influence of electrons and excitons can be slowed down, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved.

[0303] For example, the lowest bond dissociation energy of the first functional material in an anionic state may be 1.0 eV, 1.5 eV, 2.0 eV, 2.5 eV, or 3.0 eV, etc.

[0304] In some embodiments, the lowest of the bond dissociation energies of the host material in the ground state is greater than or equal to 1.50 eV.

[0305] It is understood that the lowest bond dissociation energy of the main material in the ground state can be used to characterize the molecular stability of the main material. When the lowest bond dissociation energy of the main material in the ground state is greater than or equal to 1.50 eV, the molecular stability of the main material is relatively high, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0306] For example, the lowest bond dissociation energy of the host material in the ground state may be 1.50 eV, 2.00 eV, 2.50 eV, 3.00 eV, 3.50 eV, or 4.00 eV, etc.

[0307] In some embodiments, the lowest of the bond dissociation energies of the guest material in the ground state is greater than or equal to 1.50 eV.

[0308] It is understood that the lowest bond dissociation energy of the guest material in the ground state can be used to characterize the molecular stability of the guest material. When the lowest bond dissociation energy of the guest material in the ground state is greater than or equal to 1.50 eV, the molecular stability of the guest material is relatively high, so the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0309] For example, the lowest bond dissociation energy of the guest material in the ground state may be 1.50 eV, 2.10 eV, 2.50 eV, 3.00 eV, 3.60 eV, or 4.10 eV, etc.

[0310] In some embodiments, the triplet energy level T1(H) of the host material H is less than the triplet energy level T1(G1) of the first functional material G1. That is, the triplet energy level T1(H) of the host material H and the triplet energy level T1(G1) of the first functional material G1 satisfy: T1(H) <T1(G1)。

[0311] The first functional material G1 is a material of a sub-functional layer in the first type of functional layer (ie, the hole transport functional layer 132 ) that is in direct contact with the light emitting layer 131 . For example, the first functional material G1 is a material of the electron blocking layer 1323 .

[0312] It can be understood that when the triplet energy level T1(H) of the main material H is less than the triplet energy level T1(G1) of the first functional material G1, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the first functional material are relatively small. In this way, the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), and the concentration of triplet excitons in the light-emitting layer 131 can be increased. In this way, compared with the case where the concentration of triplet excitons is low, the probability of effective collision of triplet excitons can be increased, so that the TTA effect can be enhanced, and the TTA effect can be fully utilized to improve the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0313] In some embodiments, the triplet energy level T1(H) of the host material H is less than the triplet energy level T1(D) of the guest material D. That is, the triplet energy level T1(H) of the host material H and the triplet energy level T1(D) of the guest material D satisfy: T1(H) <T1(D)。

[0314] It can be understood that when the triplet energy level T1(H) of the host material H is less than the triplet energy level T1(D) of the guest material D, after the holes and electrons recombine to form triplet excitons on the host material, the triplet excitons transferred from the host material to the guest material are relatively few. In this way, the triplet excitons can be bound to the host material, and the concentration of triplet excitons distributed on the host material can be increased. In this way, compared with the situation where the concentration of triplet excitons on the host material is low, the probability of effective collision of triplet excitons can be increased, so that the TTA effect can be enhanced, and the TTA effect can be fully utilized to improve the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0315] In some embodiments, the singlet energy level S1(H) of the host material H is greater than the singlet energy level S1(D) of the guest material D. That is, the singlet energy level S1(H) of the host material H and the singlet energy level S1(D) of the guest material D satisfy: S1(H)>S1(D).

[0316] It can be understood that when the singlet energy level S1(H) of the host material H is greater than the singlet energy level S1(D) of the guest material D, the singlet excitons transferred from the guest material to the host material are relatively small. In this way, relatively more singlet excitons can be bound to the guest material, and the concentration of singlet excitons distributed on the guest material can be increased. In this way, compared with the case where the concentration of singlet excitons on the guest material is low, relatively more singlet excitons can be used for luminescence, thereby improving the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0317] In some embodiments, the light-emitting unit 13 further includes a second type of functional layer disposed on the side of the light-emitting layer 131 close to the cathode 12; the second type of functional layer includes a third sub-functional layer, and the third sub-functional layer is in contact with the light-emitting layer 131; the material of the third sub-functional layer includes a third functional material G3. Among them, the triplet energy level T1(H) of the main material H is less than the triplet energy level T1(G3) of the third functional material G3. That is, the triplet energy level T1(H) of the main material H and the triplet energy level T1(G3) of the third functional material G3 satisfy: T1(H) <T1(G3)。

[0318] The second type of functional layer is the electron transport functional layer 133. The third sub-functional layer can be one of the electron injection layer 1331, the electron transport layer 1332 and the hole blocking layer 1333. The third functional material is the material of the sub-functional layer in the second type of functional layer (i.e., the electron transport functional layer 133) that is in direct contact with the light-emitting layer 131. For example, the third functional material G3 is the material of the hole blocking layer 1333.

[0319] It can be understood that when the triplet energy level T1(H) of the main material H is less than the triplet energy level T1(G3) of the third functional material G3, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the third functional material are relatively small. In this way, the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), and the concentration of triplet excitons in the light-emitting layer 131 can be increased. In this way, compared with the case where the concentration of triplet excitons is low, the probability of effective collision of triplet excitons can be increased, so that the TTA effect can be enhanced, and the TTA effect can be fully utilized to improve the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0320] The structures of the host material, the guest material, and the first functional material are exemplarily introduced below.

[0321] In some embodiments, the host material H is selected from any one of the structures shown in the following general formula (I).

[0322]

[0323] Wherein, R1, R2, R3, R4, R5, R6, R7 and R8 are the same or different and are independently selected from any one of hydrogen, deuterium, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted diarylamino, substituted or unsubstituted siloxane and substituted or unsubstituted silyl.

[0324] L1 and L2 are the same or different, and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group, and a substituted or unsubstituted heteroarylene group.

[0325] Ar1 and Ar2 are the same or different and are independently selected from substituted or unsubstituted aryl groups.

[0326] At least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium.

[0327] It should be noted that when R1, R2, R3, R4, R5, R6, R7 or R8 is selected from any one of a substituted alkyl group, a substituted alkoxy group, a substituted aryl group, a substituted aryloxy group, a substituted diarylamino group, a substituted siloxane group and a substituted silyl group, and / or L1 or L2 is any one of a substituted arylene group and a substituted heteroarylene group, and / or Ar1 and Ar2 are selected from substituted aryl groups, the type and number of substituents are not limited here.

[0328] It should be noted that, in the general formula (I), It is anthracenyl. In the above general formula (I), L1 and L2 can be single bonds. When L1 is a single bond, the anthracenyl and Ar1 are directly connected by a single bond. When L2 is a single bond, the anthracenyl and Ar2 are directly connected by a single bond. In the general formula (I), L1 and L2 can be any one of substituted or unsubstituted arylene and substituted or unsubstituted heteroarylene. The structure of arylene is introduced below by taking phenylene as an example. Phenyl refers to the general term for the remaining group after the hydrogen atom of one carbon atom on the benzene ring is removed. Phenylene refers to the general term for the remaining group after the hydrogen atoms on two carbon atoms on the benzene ring are removed. For the understanding of heteroarylene, you can refer to the above content, which will not be repeated here.

[0329] It can be understood that when at least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium, the main material H is a deuterated material. Since the exciton recombination site mainly occurs on the main material H, the TTF effect is also mainly realized on the main material. Therefore, compared with the case where the main material H does not contain deuterium atoms, by setting the main material H as a deuterated material, the bond dissociation energy of the main material H can be increased, the energy of the intermediate of the TTF effect can be reduced, and the bond dissociation energy of the main material H is higher than the energy of the intermediate of the TTF effect, which can reduce the probability of degradation of the main material H due to the energy of the intermediate, so that the stability of the main material H and the life of the light-emitting device 100 (for example, the first light-emitting device 101) are improved.

[0330] Moreover, when the deuterated position is the position of the carbon-hydrogen bond, a carbon-deuterium bond will be generated. The carbon-hydrogen bond is usually a relatively weak energy part in the organic material. Through deuteration, the carbon-hydrogen bond can be replaced by a carbon-deuterium bond, which can shorten the bond length, increase the bond dissociation energy, and reduce the probability of side reactions in the main material, so that the molecular stability of the main material is improved. In this way, the tolerance of the main material to the high-energy intermediates of the TTF effect can be improved, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved.

[0331] In addition, the structure shown in the general formula (I) contains an anthracene group, that is, the main material H is an anthracene derivative. During the light emission process of the light-emitting device 100, electrons and holes can recombine at the anthracene group to form triplet excitons, so that the triplet excitons have a relatively high distribution density at the anthracene group. In this way, the collision and fusion between triplet excitons can be increased, the TTA effect (for example, the TTF effect) can be enhanced, and the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0332] An exemplary structure of the host material H having the structure represented by the general formula (I) is described below.

[0333] In some examples, when R1, R2, R3, R4, R5, R6, R7 and R8 are all deuterium, and Ar1 and Ar2 do not contain deuterium, the structural formula of the host material H can be as shown below.

[0334]

[0335] In some examples, when R1, R2, R3, R4, R5, R6, R7 and R8 are all hydrogen, and Ar1 and / or Ar2 contain deuterium, the structural formula of the host material H can be as shown below.

[0336]

[0337] In some examples, when R1, R2, R3, R4, R5, R6, R7 and R8 are all deuterium, and Ar1 and / or Ar2 contain deuterium, the structural formula of the host material H can be as shown below.

[0338]

[0339]

[0340] It should be noted that the above listed structural formulas are examples of the structure of the main material H, and are not limitations on the main material H. Moreover, (Hx) in the above structural formulas is a synonym for each structural formula, and is not a part of the structural formula structure, where x is a positive integer.

[0341] In some embodiments, when the host material is a deuterated material, the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

[0342] The mass fraction of deuterium in the above-mentioned host material refers to the ratio between the relative molecular mass of deuterium atoms in the structure of the host material and the relative molecular mass of the host material molecules.

[0343] It can be understood that when the mass fraction of deuterium in the main material is greater than or equal to 1.0% and less than or equal to 4.9%, the mass fraction of deuterium in the main material is relatively high, that is, the main material contains relatively more deuterium atoms. As mentioned above, when the number of deuterium atoms in the main material is relatively large, the bond dissociation energy and stability of the main material can be improved, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved. At the same time, the molecular vibration of the main material can be reduced, and the quantum efficiency loss caused by the molecular vibration of the main material can be reduced, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) is improved. In addition, when the main material contains relatively more deuterium atoms, the energy required for the main material to undergo side reactions is also relatively high. In this way, the probability of side reactions in the main material can be relatively low, and the stability of the main material can be improved.

[0344] Exemplarily, the host material H is selected from any one of the structures shown in the general formula (I), and the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

[0345] For example, the mass fraction of deuterium in the host material may be 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 4.0% or 4.9%, etc.

[0346] In some embodiments, the guest material D is selected from any one of the structures shown in the following general formula (II).

[0347]

[0348] Wherein, A, E and F are the same or different and are independently selected from any one of a substituted or unsubstituted aromatic ring, a substituted or unsubstituted heteroaromatic ring and a substituted or unsubstituted cycloalkane ring; in the case where A, E and F are selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, the substituent may be connected with an adjacent substituent to form a substituted or unsubstituted ring.

[0349] X1 and X2 are the same or different and are independently selected from O, N(R a ) and C(R b R c ) in any one of the following. Wherein O is oxygen, N(R a ) is R a Substituted nitrogen, C(R b R c ) is R b With R c Substituted carbon.

[0350] R a , R b and R c are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl and substituted or unsubstituted heterocyclic.

[0351] At least one of A, E and F contains deuterium.

[0352] It should be noted that in the structure shown in the general formula (II), B is boron, and the relationship between X1 and the ring where B is located, X2 and the ring where B is located and A means that X1 and the ring where B is located, X2 and the ring where B is located and A are fused by sharing carbon numbers 3, 4, and 5; the relationship between X1 and the ring where B is located and F means that X1 and the ring where B is located and F are fused by sharing carbon numbers 1 and 2; the relationship between X2 and the ring where B is located and E means that X2 and the ring where B is located and E are fused by sharing carbon numbers 6 and 7. Among them, although the structure shown in the general formula (II) shows that the sizes of E and F are inconsistent with the size of A, it is only to indicate that A, E, F, X1 and the ring where B is located, and X2 and the ring where B are located are fused, and the relative sizes of the rings are not limited.

[0353] It should be noted that, when A, E and F are selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, the substituent may be connected to an adjacent substituent to form a substituted or unsubstituted ring, and the "substituent" and "adjacent substituent" mentioned here may be two substituents located on the same ring, or may be two substituents located on two adjacent rings of A, E and F, and there is no limitation here.

[0354] In some examples, when A, E and F are selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, the substituents are connected with adjacent substituents to form a substituted or unsubstituted ring containing heteroatoms such as O, N, S, etc.

[0355] It should be noted that when A, E or F is selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, and / or; R a , R b or R c When the substituent is selected from any one of a substituted alkyl group, a substituted silyl group, a substituted alkoxy group, a substituted aryl group and a substituted heterocyclic group, the type and number of the substituent are not limited herein.

[0356] It is understandable that when at least one of A, E and F contains deuterium, the guest material D is a deuterated material. Compared with the case where the guest material D does not contain deuterium atoms, as described above, first, the bond dissociation energy of the guest material D can be increased, so that the probability of the guest material D being degraded by the energy of the intermediate is relatively lower, and at the same time, the probability of the guest material D having a side reaction can be reduced, so that the stability of the guest material D and the life of the light-emitting device 100 (for example, the first light-emitting device 101) are improved. Second, the energy loss caused by the vibration of the guest material molecules can be reduced, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) is improved. Third, the molecular vibration can be suppressed, the emission spectrum of the guest material D can be narrowed, and the color purity of the light-emitting device 100 (for example, the first light-emitting device 101) can be relatively high.

[0357] An exemplary structure of the guest material D having the structure represented by the general formula (II) is described below.

[0358] In some examples, when X1 and X2 are both N(R a ), and two R a When no deuterium is contained, the structural formula of the guest material D can be shown as follows.

[0359]

[0360] In some examples, when X1 and X2 are both N(R a ), and two R aWhen both contain deuterium, the structural formula of the guest material D can be shown as follows.

[0361]

[0362]

[0363] In some examples, when X1 is N(R a ), R a Contains deuterium, and X2 is C(R b R c ), the structural formula of the guest material D can be shown as follows.

[0364]

[0365] It should be noted that the above-listed structural formulas are examples of the structures of the object material D, and are not limitations on the object material D. Moreover, (Dx) in the above structural formulas is a synonym for each structural formula, and is not a part of the structural formula structure, where x is a positive integer.

[0366] In some embodiments, at least one of A, E, and F has a substituent comprising tert-butyl.

[0367] In the related art, tert-butyl is the group left after removing the hydrogen atom on the methine from the 2-methylpropane molecule, and has a structure similar to a tetrahedron. Therefore, when tert-butyl is used as a substituent, it has a better stereo effect and steric effect.

[0368] It can be understood that when at least one of A, E and F includes a tert-butyl group, the structure shown in the general formula (II) has a certain stereoscopic property, which improves the stereoscopic property of the structure of the guest material D and reduces the planarity of the structure of the guest material D. Since the planarity of the material structure is low, the distance between molecules can be increased, the intermolecular forces can be reduced, the orderly stacking of molecules can be reduced, and the quenching of excitons can be relatively less. Therefore, by setting that at least one of A, E and F includes a tert-butyl group, the quenching of excitons on the guest material D can be relatively less, and the exciton concentration on the guest material can be relatively high, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0369] It should be noted that, when at least one of A, E and F contains deuterium and at least one of the substituents includes a tert-butyl group, the ring containing deuterium and the ring containing a tert-butyl group in A, E and F may be the same ring or different rings, and there is no limitation here. Moreover, when the substituent includes a tert-butyl group, part of the hydrogen in the tert-butyl group may be replaced by deuterium, that is, the tert-butyl group may be a tert-butyl group substituted by deuterium, and there is no limitation here.

[0370] The following describes an exemplary structure of the guest material D when, in the structure represented by the general formula (II), at least one of the substituents of A, E and F includes a tert-butyl group.

[0371] In some examples, when the substituent of E and the substituent of F both include tert-butyl groups, the structural formula of the guest material D can be as shown in (D-1), (D-2), and (D-3) above.

[0372] It should be noted that the structural formula listed above is an example of the structure of the guest material D, and does not limit the guest material D.

[0373] In some embodiments, when the guest material is a deuterated material, the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

[0374] The mass fraction of deuterium in the above-mentioned guest material refers to the ratio between the relative molecular mass of deuterium atoms in the structure of the guest material and the relative molecular mass of the guest material molecules.

[0375] It can be understood that when the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%, the mass fraction of deuterium in the guest material is relatively high, that is, the guest material contains relatively more deuterium atoms. As mentioned above, on the one hand, when the number of deuterium atoms in the guest material is relatively large, the bond dissociation energy and stability of the guest material can be improved, so that the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved. At the same time, the molecular vibration of the guest material can be reduced, and the quantum efficiency loss caused by the molecular vibration of the guest material can be reduced, so that the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101) is improved. On the other hand, when the number of deuterium atoms in the guest material is relatively large, the molecular vibration can be suppressed, the emission spectrum of the guest material can be narrowed, and the color purity of the light-emitting device 100 (for example, the first light-emitting device 101) is relatively high. On the other hand, when the guest material contains relatively more deuterium atoms, the energy required for the guest material to undergo side reactions is relatively high. In this way, the probability of the guest material undergoing side reactions can be relatively low, thereby improving the stability of the guest material.

[0376] Exemplarily, the guest material D is selected from any one of the structures represented by the general formula (II), and the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

[0377] For example, the mass fraction of deuterium in the guest material may be 0.1%, 1.0%, 3.0%, 5.0%, 7.0% or 8.5%, etc.

[0378] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III).

[0379]

[0380] Wherein, Z is selected from O, S, N (R d ) and C(R e R f ) wherein O is oxygen, S is sulfur, N(R d ) is R d Substituted nitrogen, C(R e R f ) is R e With R f Substituted carbon.

[0381] R d , R e and R f are the same or different and are independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl.

[0382] L3 and L4 are the same or different, and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group and a substituted or unsubstituted heteroarylene group.

[0383] e and f are the same or different and are independently selected from any one of 1, 2, 3 and 4.

[0384] Ar3, Ar4, Ar5 and Ar6 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S. Among them, O is oxygen, S is sulfur, and N is nitrogen.

[0385] p and q are the same or different and are independently selected from any one of 0, 1 and 2; and the sum of p and q is greater than or equal to 1 and less than or equal to 2.

[0386] Regarding the structure shown in general formula (III), the following points need to be explained:

[0387] The description of L3 or L4 being a single bond here can refer to the above description of L1 or L2 being a single bond; the description of the aryl group and the heteroaryl group here can refer to the above description of the aryl group and the heteroaryl group; the description of the arylene group and the heteroarylene group here can refer to the above description of the arylene group and the heteroarylene group, which will not be repeated here.

[0388] The aryl group of Cx refers to an aryl group having x carbon (C) atoms in total. Wherein, x is a positive integer, and the same applies below. For understanding of other heteroaryl groups such as Cx, please refer to the above content, and no further description will be given here.

[0389] The connection position of L3 and part IIIA shown in the general formula (III) means that L3 can be connected to any carbon with a substitution position among carbons 1', 2', 3', and 4' of part IIIA. For the understanding of the connection position of deuterium (D) and part IIIA, the connection position of L4 and part IIIA, etc., please refer to the above content and will not be repeated here. Among them, the connection positions of any two deuteriums (D) among e deuteriums (D) and f deuteriums (D) and part IIIA are all different. Moreover, when e is 4, p is 0; when f is 4, q is 0.

[0390] When the sum of p and q is 1, the structure represented by the general formula (III) contains one triarylamine structure; when the sum of p and q is 2, the structure represented by the general formula (III) contains two triarylamine structures.

[0391] When R d , R e or R f When Ar3, Ar4, Ar5 or Ar6 is selected from any one of substituted C6-C60 aryl and substituted C2-C60 heteroaryl, the type and number of substituents are not limited here.

[0392] It is understood that when Z is oxygen, the IIIA part is a dibenzofuran structure; when Z is sulfur, the IIIA part is a dibenzothiophene structure; when Z is nitrogen, the IIIA part is a carbazole structure. When the IIIA part is a dibenzofuran structure, a dibenzothiophene structure or a carbazole structure, the positions of carbons 1' to 8' and the position of Z have high reactivity, and when chemical reactions occur at these positions, the first functional material may be degraded. In the structure shown in the above general formula (III), e deuteriums (D) and f deuteriums (D) are connected to (e+f) of the carbons 1' to 8', that is, multiple deuteriums replace hydrogens located at higher reaction active sites. In this way, the bond length can be shortened, the bond dissociation energy can be increased, and the molecular stability of the first functional material can be improved; at the same time, the probability of side reactions in the first functional material can be reduced. In this way, the electrical stability of the first functional material can be improved, the electronic resistance of the first functional material can be improved, and the degradation of the first functional material caused by electrons and excitons can be slowed down, so that the stability of the first functional material is improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved.

[0393] Moreover, when the IIIA part is a dibenzofuran structure, a dibenzothiophene structure or a carbazole structure, the triplet energy level of the first functional material is relatively high, so that the difference between the triplet energy level of the first functional material and the triplet energy level of the main material is relatively large; in this way, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the first functional material are relatively small, so that the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), the triplet exciton concentration in the light-emitting layer 131 can be increased, the TTA effect can be enhanced, and the TTA effect can be fully utilized to improve the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0394] When Z is carbon, the IIIA part is a fluorene or spirofluorene structure. In the fluorene or spirofluorene structure, the sp3 carbon (i.e., Z) is an unstable part in the molecule and may cause defects due to chemical reactions. In the structure shown in the above general formula (III), e deuteriums (D) and f deuteriums (D) are connected to (e+f) of the carbons 1' to 8' to form a multi-deuterium-substituted fluorene or spirofluorene structure. On the one hand, the molecular stability and electrical stability of the first functional material can be improved, the electronic resistance of the first functional material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. On the other hand, the zero point energy (Zero Point Energy), that is, the energy of the ground state, can be reduced, and the binding length of deuterium-carbon is less than the binding length of hydrogen-carbon, which can reduce the molecular core volume (Molecular hardcore volume), thereby reducing the electronic polarizability (Electroical polarizability). This property can reduce the crystallinity of the film, that is, the amorphous state. The amorphous state reduces grain boundaries through isotropic and homogeneous properties, allowing charges to flow quickly and improving the hole mobility of the first functional material.

[0395] An exemplary structure of the first functional material G1 having a structure represented by the general formula (III) is described below.

[0396] In some examples, when Z is oxygen, the structural formula of the first functional material G1 can be as shown below.

[0397]

[0398]

[0399] In some examples, when Z is sulfur, the structural formula of the first functional material G1 can be as shown below.

[0400]

[0401]

[0402] In some examples, when Z is nitrogen substituted with a phenyl group, the structural formula of the first functional material G1 may be as shown below.

[0403]

[0404] In some examples, when Z is carbon substituted with a methyl group, the structural formula of the first functional material G1 may be as shown below.

[0405]

[0406] It should be noted that the above-listed structural formulas are examples of the structure of the first functional material G1, and are not limitations on the first functional material G1. Moreover, (G1-x) in the above structural formulas is a synonym for each structural formula, and is not a part of the structural formula structure, where x is a positive integer.

[0407] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (III-A).

[0408]

[0409] wherein g and h are the same or different and are independently selected from any one of 0, 1, 2 and 3.

[0410] When carbon atoms 3' and 6' in the structure represented by general formula (III) are connected to deuterium, the structure represented by general formula (III) can be transformed into the structure represented by general formula (III-A).

[0411] It can be understood that in the IIIA part of the structure shown in the general formula (III), the reaction activity of carbons 3' and 6' is relatively high compared to carbons 1', 2', 4', 5', 7', and 8'. When chemical reactions occur at the positions of carbons 3' and 6', the first functional material may be degraded. In the structure shown in the general formula (III-A) above, deuterium replaces the hydrogen connected to carbons 3' and 6'. In this way, the bond length can be shortened, the bond dissociation energy can be increased, and the probability of side reactions in the first functional material can be reduced, thereby improving the molecular stability of the first functional material. In this way, the electrical stability of the first functional material can be improved, the electronic resistance of the first functional material can be improved, the degradation of the first functional material caused by the influence of electrons and excitons can be slowed down, the stability of the first functional material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0412] An exemplary structure of the first functional material G in the structure represented by the general formula (III-A) is described below.

[0413] In some examples, when Z is oxygen, the structural formula of the first functional material G1 can be as shown in (G1-1) to (G1-6) above.

[0414] In some examples, when Z is sulfur, the structural formula of the first functional material G1 can be as shown in (G1-8) to (G1-11) above.

[0415] In some examples, when Z is carbon substituted with a methyl group, the structural formula of the first functional material G1 can be as shown in (G1-14) and (G1-15) above.

[0416] It should be noted that the structural formula listed above is an example of the structure of the first functional material G1, and is not a limitation to the first functional material G1.

[0417] In some embodiments, the first functional material is selected from any one of the structures shown in the following general formula (IV).

[0418]

[0419] Wherein, L5 is selected from any one of a single bond and a substituted or unsubstituted C6-C60 arylene group.

[0420] Ar7 and Ar8 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S. Among them, N is nitrogen, O is oxygen, and S is sulfur.

[0421] R9 and R 10 The same or different, each independently selected from any one of hydrogen, deuterium, halogen, cyano, nitro, amino, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C3-C60 cycloalkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C6-C60 aryl and substituted or unsubstituted C2-C60 heteroaryl; or may be connected with adjacent substituents to form a substituted or unsubstituted ring; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S.

[0422] m and n are the same or different and are independently selected from any one of 1, 2, 3 and 4.

[0423] At least one R9 is deuterium.

[0424] At least one R 10 For deuterium.

[0425] The description of L5 being a single bond here may refer to the above description of L1 being a single bond; the description of the aryl group of Cx, the alkyl group of Cx, etc. here may refer to the above description of the aryl group of Cx, the alkyl group of Cx; the description of the aryl group and the heteroaryl group here may refer to the above description of the aryl group and the heteroaryl group; the description of the arylene group and the heteroarylene group here may refer to the above description of the arylene group and the heteroarylene group, which will not be repeated here.

[0426] When L5 is selected from a substituted C6-C60 arylene group, and / or Ar7 or Ar8 is selected from any one of a substituted C6-C60 aryl group and a substituted C2-C60 heteroaryl group, and / or R9 or R 10 When any one is selected from a substituted C1-C60 alkyl group, a substituted C3-C60 cycloalkyl group, a substituted C2-C60 alkenyl group, a substituted C6-C60 aryl group and a substituted C2-C60 heteroaryl group, the type and number of the substituents are not limited herein.

[0427] It is understood that the structure shown in the general formula (IV) contains a carbazole group, and the positions of carbon numbers 1" to 8" in the carbazole group have high reactivity. When chemical reactions occur at these positions, the first functional material may be degraded. In the structure shown in the general formula (IV), m deuterium R9 and n R 10 is connected to (m+n) of the carbon atoms 1" to 8", and at least one R9 is deuterium, and at least one R 10 That is, a plurality of deuteriums replace hydrogen at higher reaction active sites, thereby shortening the bond length, increasing the bond dissociation energy, and improving the molecular stability of the first functional material; at the same time, reducing the probability of side reactions in the first functional material, thereby improving the electrical stability of the first functional material, improving the electronic resistance of the first functional material, slowing down the degradation of the first functional material caused by electrons and excitons, improving the stability of the first functional material, and improving the life of the light-emitting device 100 (for example, the first light-emitting device 101).

[0428] Moreover, since the structure shown in the general formula (IV) contains a carbazole group, the triplet energy level of the first functional material is relatively high, and the difference between the triplet energy level of the first functional material and the triplet energy level of the main material is relatively large; in this way, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the first functional material are relatively small. In this way, the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), the concentration of triplet excitons in the light-emitting layer 131 can be increased, the TTA effect can be enhanced, and the TTA effect can be fully utilized to improve the efficiency of the light-emitting device 100 (for example, the first light-emitting device 101).

[0429] An exemplary structure of the first functional material G1 having a structure represented by the general formula (IV) is described below.

[0430] In some examples, when Ar7 and Ar8 include biphenyl groups, the structural formula of the first functional material G1 may be as shown below.

[0431]

[0432]

[0433] In some examples, when Ar7 and Ar8 include a naphthyl group, the structural formula of the first functional material G1 may be as shown below.

[0434]

[0435] As for the first functional material shown in the above structural formulas (G1-16) to (G1-21), it can be known that in the structure shown in the general formula (VI), the deuterium substitution position can be located at the position of carbon No. 3", and carbon No. 6". Compared with carbon No. 1", 2", 4", 5", 7", and 8", the reaction activity of carbon No. 3", and carbon No. 6 is relatively high. By setting the position of carbon No. 3", and carbon No. 6 for deuteration, the molecular stability of the position of carbon No. 3", and carbon No. 6 can be improved, so that the stability of the first functional material is relatively higher, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) is improved.

[0436] It should be noted that the above-listed structural formulas are examples of the structure of the first functional material G1, and are not limitations on the first functional material G1. Moreover, (G1-x) in the above structural formulas is a synonym for each structural formula, and is not a part of the structural formula structure, where x is a positive integer.

[0437] In some embodiments, when the first functional material is a deuterated material, the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0438] The mass fraction of deuterium in the first functional material refers to the ratio between the relative molecular mass of deuterium atoms in the structure of the first functional material and the relative molecular mass of the first functional material molecules.

[0439] It can be understood that when the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%, the mass fraction of deuterium in the first functional material is relatively high, that is, the first functional material contains relatively more deuterium atoms. As mentioned above, when the number of deuterium atoms in the first functional material is relatively large, the bond dissociation energy and stability of the first functional material can be improved, the electrical stability of the first functional material can be improved, the electronic resistance of the first functional material can be improved, the degradation of the first functional material caused by the influence of electrons and excitons can be slowed down, the stability of the first functional material can be improved, and the life of the light-emitting device 100 (for example, the first light-emitting device 101) can be improved. Moreover, when the first functional material contains relatively more deuterium atoms, the energy required for the first functional material to undergo side reactions is also relatively high. In this way, the probability of the first functional material undergoing side reactions can be relatively low, and the stability of the first functional material can be improved.

[0440] In some examples, the first functional material is selected from any one of the structures shown in formula (III), and the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0441] In other examples, the first functional material is selected from any one of the structures shown in the general formula (III-A), and the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0442] In some other examples, the first functional material is selected from any one of the structures shown in general formula (IV), and the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

[0443] For example, the mass fraction of deuterium in the guest material may be 0.15%, 1.00%, 2.00%, 3.00%, 4.00% or 5.50%, etc.

[0444] In order to objectively evaluate the technical effects of the embodiments of the present disclosure, the technical solutions provided by the present disclosure are described in detail and exemplarily through the following experimental examples and comparative examples. According to different device structure types, the following experimental examples and comparative examples are divided into the first group of experimental examples, the second group of experimental examples and the third group of experimental examples.

[0445] The first set of test cases

[0446] The following embodiments and comparative examples use different materials to make the light-emitting layer 131 and the electron blocking layer 1323 of the first light-emitting device 101, and compare the voltage, current efficiency, and device life of the first light-emitting device 101.

[0447] In the following comparative examples and embodiments, the structure of the first light emitting device 101 and the test conditions of the first light emitting device 101 are the same.

[0448] The first light emitting device 101 is a single-layer light emitting device, and its structure is as follows: Figure 6 The method for preparing a display panel including the first light-emitting device 101 includes: using a substrate 210 (glass substrate) provided with a pixel defining layer 221 and an anode 11 as a backplane, placing the backplane in a vacuum chamber of a vacuum evaporation device, and evacuating the chamber to a vacuum of 1×10 -5 Pa~1×10 -6 After Pa, the hole injection layer 1321, the hole transport layer 1322, the electron blocking layer 1323, the light emitting layer 131, the hole blocking layer 1333, the electron transport layer 1332, the electron injection layer 1331, the cathode 12, and the covering layer 15 are sequentially formed on the backplane, including the hole injection layer 1321, the hole transport layer 1322, the electron blocking layer 1323, the light emitting layer 131, the hole blocking layer 1333, the electron transport layer 1332, the electron injection layer 1331, the cathode 12, and the covering layer 15. Before use, the backplane is firstly ultrasonically treated in a detergent, then rinsed with deionized water, and then ultrasonically treated in an acetone-ethanol mixed solvent to remove oil, and then dried in a clean environment until the water and solvent are removed.

[0449] It should be noted that the thicknesses of the hole injection layer 1321, hole transport layer 1322, electron blocking layer 1323, light-emitting layer 131, hole blocking layer 1333, electron transport layer 1332, electron injection layer 1331, cathode 12, and covering layer 15 in the embodiment and the comparative example are the same, which are 10nm, 100nm, 10nm, 20nm, 5nm, 30nm, 1nm, 13nm, and 60nm, respectively.

[0450] The materials of the anode 11 , the hole injection layer 1321 , the hole transport layer 1322 , the hole blocking layer 1333 , the electron transport layer 1332 , the electron injection layer 1331 , and the cathode 12 in the embodiment and the comparative example are the same. Among them, the material of the anode 11 is indium tin oxide (ITO); the material of the hole injection layer 1321 is a mixed material obtained by mixing a hole transport material (structure as shown in the aforementioned structural formula (HTL)) and a hole injection material (structure as shown in the following formula (HIL)) in a mass ratio of 98:2; the structure of the material of the hole transport layer 1322 is as shown in the aforementioned structural formula (HTL); the structure of the material of the hole blocking layer 1333 is as shown in the following formula (HBL); the material of the electron transport layer 1332 is a mixed material obtained by mixing a first electron transport material (structure as shown in the following formula (ETL)) and a second electron transport material (structure as shown in the following formula (LiQ)) in a mass ratio of 1:1; the material of the electron injection layer 1331 is ytterbium; the material of the cathode 12 is a magnesium-silver alloy (Mg:Ag=1:9).

[0451]

[0452] The materials of the electron blocking layer 1323 and the light-emitting layer 131 in the embodiments and comparative examples are different, wherein the materials of the electron blocking layer 1323 in the comparative examples and some embodiments include a comparative first functional material, and the structure is shown in the following formula (R-G1); the materials of the light-emitting layer 131 in the comparative examples and some embodiments include a comparative host material and a comparative guest material, and the structure of the comparative host material is shown in the following formula (RH); the structure of the comparative guest material is shown in the following formula (RD).

[0453]

[0454] It should be noted that (HIL), (HBL), (ETL), (LiQ), (RH), (RD), and (R-G1) in the above structural formulas are aliases for each structural formula and are not part of the structural formula structure.

[0455] The materials of the light emitting layer 131 and the electron blocking layer 1323 of the first light emitting device 101 of the embodiment and the comparative example are described below respectively.

[0456] In Example 1, the light-emitting layer 131 includes a host material H and a guest material D, the structural formula of the host material H is shown in (H-4); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-13).

[0457] In Example 2, the light-emitting layer 131 includes a host material H and a guest material D, the structural formula of the host material H is shown in (H-5); the structural formula of the guest material D is shown in (D-6). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-7).

[0458] In Example 3, the light-emitting layer 131 includes a host material H and a guest material D, the structural formula of the host material H is shown in (H-4); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-18).

[0459] In Example 4, the light-emitting layer 131 includes a host material H and a guest material D, the structural formula of the host material H is shown in (H-5); the structural formula of the guest material D is shown in (D-6). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-20).

[0460] In Example 5, the light-emitting layer 131 includes a host material H and a guest material D, the structural formula of the host material H is shown in (H-5); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (R-G1).

[0461] In Example 6, the light-emitting layer 131 includes a comparative host material and a comparative guest material, the structural formula of the comparative host material is shown in (RH); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the comparative host material and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-13).

[0462] In Example 7, the light-emitting layer 131 includes a host material H and a comparative guest material, the structural formula of the host material H is shown in (H-4); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the host material H and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (R-G1).

[0463] In Example 8, the light-emitting layer 131 includes a comparative host material and a guest material D, the structural formula of the comparative host material is shown in (RH); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the comparative host material and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (R-G1).

[0464] In Example 9, the light-emitting layer 131 includes a comparative host material and a guest material D, the structural formula of the comparative host material is shown in (RH); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the comparative host material and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (G1-18).

[0465] In Comparative Example 1, the light-emitting layer 131 includes a comparative host material and a comparative guest material, the structural formula of the comparative host material is shown in (RH); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the comparative host material and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323 is shown in (R-G1).

[0466] In order to more clearly describe the differences in the structural formulas of the main material, guest material and the material of the electron blocking layer 1323 used in the embodiments and comparative examples, the following Table 1 is used to more clearly show the structural formulas of the main material, guest material and the material of the electron blocking layer 1323 used in the embodiments and comparative examples.

[0467] Table 1

[0468] Main material Object material Materials for the electron blocking layer Example 1 H-4 D-4 G1-13 Example 2 H-5 D-6 G1-7 Example 3 H-4 D-4 G1-18 Example 4 H-5 D-6 G1-20 Example 5 H-5 D-4 R-G1 Example 6 RH RD G1-13 Example 7 H-4 RD R-G1 Example 8 RH D-4 R-G1 Example 9 RH D-4 G1-18 Comparative Example 1 RH RD R-G1

[0469] It should be noted that "Ax" in Table 1 refers to the corresponding structural formula Ax. For example, the sub-grid content corresponding to the host material H in Example 1 is "H-4", which means that the structural formula of the host material H in the light-emitting layer 131 of Example 1 is as shown in (H-4). The structural formulas represented by Hx, Dx, G1-x (x is a positive integer), RH, RD, and R-G1 refer to the above content and are not repeated here.

[0470] In this group of test examples, Gaussian 09 software was used to calculate the overlap rate of the HOMO state density of the material of the electron blocking layer 1323 and the HOMO state density of the material of the hole transport layer 1322 (the structure is shown in the above structural formula (HTL)), and the overlap rate of the HOMO state density of the material of the electron blocking layer 1323 and the HOMO state density of the main material by simulation, and the results are shown in Table 2. Among them, the process of the simulation calculation method includes: after implementing a deposition simulation on hundreds to thousands of molecules (for example, five hundred molecules), the HOMO energy of each material is obtained by quantum mechanics calculation, and the HOMO state density of each material is obtained on this basis. Then, the distribution difference of the HOMO state density of the material of the electron blocking layer 1323 and the material of the hole transport layer 1322 (the structure is shown in the above structural formula (HTL)) is compared, and the distribution difference of the HOMO state density of the material of the electron blocking layer 1323 and the HOMO state density of the main material is compared, and the overlap ratio is percentageized to obtain the overlap rate of the HOMO state density.

[0471] Table 2

[0472] HOMO state density overlap rate (%) (G1-13) and (H-4) 12 (G1-7) and (H-4) 16 (G1-13) and (H-5) 23 (G1-7) and (H-5) 32 (G1-18) and (H-4) 25 (G1-20) and (H-4) 29 (G1-18) and (H-5) 19 (G1-20) and (H-5) 22 (G1-13) and (HTL) 55 (G1-7) and (HTL) 68 (G1-18) and (HTL) 60 (G1-20) and (HTL) 74

[0473] As can be seen from Table 2, the overlap rate of HOMO state density between the first functional materials with structures such as those shown in formulas (G1-13), (G1-7), (G1-18), and (G1-20) and the main materials with structures such as those shown in formulas (H-4) and (H-5) is between 12% and 32%, which has a relatively high overlap rate. The overlap rate of HOMO state density between the first functional materials with structures such as those shown in formulas (G1-13), (G1-7), (G1-18), and (G1-20) and the second functional material (i.e., the material of the electron transport layer 1322) with the structure shown in the general formula (HTL) is between 55% and 74%, which has a relatively high overlap rate.

[0474] In this group of test examples, simulation software was used to calculate the hole reorganization energy and electron reorganization energy of the above-mentioned main materials, and the absolute value of the difference between the electron reorganization energy and the hole reorganization energy was calculated. The results are shown in Table 3.

[0475] Table 3

[0476] The absolute value of the difference between the electron reorganization energy and the hole reorganization energy (eV) H-4 0.02 H-5 0.05

[0477] It can be seen from Table 3 that the differences between the electron reorganization energy and the hole reorganization energy of the host materials with structures such as those shown in Formula (H-4) and Formula (H-5) are 0.02 eV and 0.05 eV, respectively, both less than 0.1 eV.

[0478] In this group of test examples, the thermal decomposition temperature Td (i.e., the temperature corresponding to 5% weight loss) of the above-mentioned main material, guest material, and first functional material was tested using a thermogravimetric analyzer (TGA). The test was carried out in a nitrogen atmosphere, and the test temperature range was from room temperature to 600°C, and the heating rate was 10°C / min. In addition, in this group of test examples, the dipole moment (Debye) of the above-mentioned main material, guest material, and first functional material was calculated using Gaussian 09 software. The results of the thermal decomposition temperature Td and the dipole moment are shown in Table 4.

[0479] Table 4

[0480] Thermal decomposition temperature Td(℃) Dipole moment (D) H-4 425 0.14 H-5 439 0.13 D-4 371 0.08 D-6 386 0.08 G1-13 416 0.15 G1-7 402 0.21 G1-18 415 0.20 G1-20 409 0.22

[0481] It can be seen from Table 4 that the thermal decomposition temperatures of the main materials with structures shown in formula (H-4) and formula (H-5), the guest materials with structures shown in formula (D-4) and formula (D-6), and the first functional materials with structures shown in formula (G1-13), (G1-7), (G1-18) and (G1-20) are in the range of 371°C to 439°C, which are all relatively high, indicating that the above materials have good thermal stability.

[0482] It can be seen from Table 4 that the dipole moments of the main materials with structures shown in formula (H-4) and formula (H-5), the guest materials with structures shown in formula (D-4) and formula (D-6), and the first functional materials with structures shown in formula (G1-13), (G1-7), (G1-18) and (G1-20) are in the range of 0.08D to 0.22D, all of which are greater than 0D, indicating that the molecules of the above materials are asymmetric.

[0483] Based on the above materials, the voltage (V), current efficiency (cd / A), and device life of the first light emitting device 101 of Examples 1 to 9 and Comparative Example 1 were tested. The data results of voltage (V), current efficiency (cd / A), and device life are based on Comparative Example 1, and the test results are shown in Table 5 below. The device life is characterized by the parameter LT95.

[0484] Table 5

[0485] Voltage efficiency Device life Example 1 92％ 119％ 152％ Example 2 94％ 117％ 133％ Example 3 97％ 108％ 128％ Example 4 96％ 106％ 111％ Example 5 96％ 105％ 109％ Example 6 97％ 102％ 103％ Example 7 97％ 102％ 105％ Example 8 98％ 99％ 99％ Example 9 97％ 101％ 102％ Comparative Example 1 100％ 100％ 100％

[0486] As can be seen from Table 5, compared with Example 1, the device lifespans of Examples 1 to 4 are in the range of 111% to 152%, which are relatively high. This is because in the first light-emitting device 101 of Examples 1 to 4, the main material H, the guest material D, and the material of the electron blocking layer 1323 (i.e., the first functional material) are all deuterated materials, while in Comparative Example 1, the comparative main material RH, the comparative guest material RD, and the comparative first functional material R-G1 are all materials that do not contain deuterium atoms. Since deuterated materials have relatively high bond dissociation energy, the stability of the material can be improved. When the main material H, the guest material D, and the material of the electron blocking layer 1323 (i.e., the first functional material) are all deuterated materials, the material of the first light-emitting device 101 contains relatively more deuterium atoms, and the stability of the three materials is improved. Moreover, under the synergistic effect of the three deuterated materials, the first light-emitting device 101 can exhibit a relatively excellent device lifespan.

[0487] Compared with Comparative Example 1, as shown in Table 5, the device efficiencies of Examples 1 to 4 are in the range of 106% to 119%, which are relatively high. This is because in the first light-emitting device 101 of Examples 1 to 4, the host material H, the guest material D, and the material of the electron blocking layer 1323 (i.e., the first functional material) are all deuterated materials, while in Comparative Example 1, the comparative host material RH, the comparative guest material RD, and the comparative first functional material R-G1 are all materials that do not contain deuterium atoms. When the host material H and the guest material D are deuterated materials, the molecular vibrations are relatively small, so that the quantum efficiency loss caused by the molecular vibrations of the host material H and the guest material D is relatively small, so that the efficiency of the first light-emitting device 101 is relatively high.

[0488] Compared with Comparative Example 1, Example 5, Example 7, and Example 8, see Table 5, the device life of Example 5, Example 7, and Example 8 is relatively high. This is because in the first light-emitting device 101 of Example 5, Example 7, and Example 8, the main material H, and / or the guest material D are all deuterated materials, while in Comparative Example 1, the comparative main material RH and the comparative guest material RD are materials that do not contain deuterium atoms. Among them, the main material or the comparative main material is the position where high-energy excitons are produced by compounding, and the guest material or the comparative guest material is a material that receives the energy transferred by the main material or the comparative main material and radiates light. Since the deuterated material has a relatively high bond dissociation energy, the electrical stability of the material can be improved. When the main material H, and / or the guest material D are all deuterated materials, the main material H, and / or the guest material D have relatively high electrical stability, which can improve the tolerance to high-energy excitons and high-energy intermediates of the TTA effect, so that the first light-emitting device 101 exhibits a relatively excellent device life.

[0489] Compared with Comparative Example 1, Example 6 and Example 9, please refer to Table 5, the device life of Example 6 and Example 9 is relatively high. This is because in the first light-emitting device 101 of Example 6 and Example 9, the material of the electron blocking layer 1323 (i.e., the first functional material) is a deuterated material, while in Comparative Example 1, the material of the electron blocking layer 1323 (i.e., the first functional material for comparison) is a material that does not contain deuterium atoms. Since the deuterated material has a relatively high bond dissociation energy, the electrical stability of the material can be improved. When the material of the electron blocking layer 1323 is a deuterated material, the material of the electron blocking layer 1323 has a relatively high electrical stability, which can improve the tolerance to carriers (electrons or holes) and excitons, so that the first light-emitting device 101 exhibits a relatively excellent device life.

[0490] As shown in Table 5, the device efficiencies of Examples 6 and 9 are relatively high compared with Comparative Example 1. This is because in the first light-emitting devices 101 of Examples 6 and 9, the structure of the material of the electron blocking layer 1323 (i.e., the first functional material) is selected from the structure shown in Formula (III) or Formula (IV), while in Comparative Example 1, the material of the electron blocking layer 1323 (i.e., the first functional material for comparison) does not conform to the structure shown in Formula (III) or Formula (IV). Since the structure represented by general formula (III) or general formula (IV) contains a carbazole group, a dibenzofuran group, a dibenzothiophene group, a fluorene group or a spirofluorene group, the triplet energy level of the first functional material can be relatively high, and the difference between the triplet energy level of the first functional material and the triplet energy level of the main material can be relatively large; in this way, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the first functional material are relatively small, so that the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), the triplet exciton concentration in the light-emitting layer 131 can be increased, the TTA effect can be enhanced, the TTA effect can be fully utilized, and the efficiency of the first light-emitting device 101 can be improved.

[0491] It can be seen from the above embodiments and comparative examples that the present disclosure can improve the efficiency of the stacked light-emitting device 100 (for example, the first light-emitting device 101) and the device life of the stacked light-emitting device 100 (for example, the first light-emitting device 101) by setting the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material to be greater than 0% and less than or equal to 90%. Moreover, by setting that the host material H is selected from any one of the structures represented by the general formula (I), the guest material D is selected from any one of the structures represented by the general formula (II), and the first functional material G1 is selected from any one of the structures represented by the general formula (III) or the general formula (IV), the efficiency of the single-layer light-emitting device 100 (for example, the first light-emitting device 101) can be further improved, and the device life of the single-layer light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0492] The second group of test cases

[0493] The following embodiments and comparative examples use different materials to make the light-emitting layer 131 and the electron blocking layer 1323 of the first light-emitting device 101, and compare the voltage, current efficiency, and device life of the first light-emitting device 101.

[0494] In the following comparative examples and embodiments, the structure of the first light emitting device 101 and the test conditions of the first light emitting device 101 are the same.

[0495] The first light emitting device 101 is a stacked light emitting device, and its structure is as follows: Fig.16 Specifically, the first light-emitting device 101 includes a stacked anode 11, a hole injection layer 1321, a hole transport layer 1322a, an electron blocking layer 1323a, a light-emitting layer 131B-a, a hole blocking layer 1333a, an electron generating layer 141, a hole generating layer 142, a hole transport layer 1322b, an electron blocking layer 1323b, a light-emitting layer 131B-b, a hole blocking layer 1333b, an electron transport layer 1332 and a cathode 12. Among them, the hole injection layer 1321, the hole transport layer 1322a, the electron blocking layer 1323a, the light-emitting layer 131B-a, and the hole blocking layer 1333a located on the side close to the anode 11 constitute the first light-emitting unit 13, and the hole transport layer 1322b, the electron blocking layer 1323b, the light-emitting layer 131B-b, the hole blocking layer 1333b, the electron transport layer 1332, and the electron injection layer 1331 located on the side close to the cathode 12 constitute the second light-emitting unit 13.

[0496] The method for preparing a display panel including the first light-emitting device 101 comprises: using a substrate 210 (glass substrate) provided with a pixel defining layer 221 and an anode 11 as a backplane, placing the backplane in a vacuum chamber of a vacuum evaporation device, and evacuating the vacuum chamber to 1×10-5 Pa~1×10 -6 After Pa, the materials of the hole injection layer 1321, the materials of the hole transport layer 1322a, the materials of the electron blocking layer 1323a, the materials of the light-emitting layer 131B-a, the materials of the hole blocking layer 1333a, the materials of the electron generating layer 141, the materials of the hole generating layer 142, the materials of the hole transport layer 1322b, the materials of the electron blocking layer 1323b, the materials of the light-emitting layer 131B-b, the materials of the hole blocking layer 1333b, the materials of the electron transport layer 1332, the materials of the electron ... The material of the sub-injection layer 1331 and the material of the cathode 12 are sequentially formed on the back plate into a hole injection layer 1321, a hole transport layer 1322a, an electron blocking layer 1323a, a light-emitting layer 131B-a, a hole blocking layer 1333a, an electron generating layer 141, a hole generating layer 142, a hole transport layer 1322b, an electron blocking layer 1323b, a light-emitting layer 131B-b, a hole blocking layer 1333b, an electron transport layer 1332, an electron injection layer 1331, and a cathode 12. Before use, the back plate is firstly ultrasonically treated in a detergent, then rinsed with deionized water, and then ultrasonically treated in an acetone-ethanol mixed solvent to remove oil, and then dried in a clean environment until the water and solvent are removed.

[0497] It should be noted that the thicknesses of the hole injection layer 1321, hole transport layer 1322a, electron blocking layer 1323a, light-emitting layer 131B-a, hole blocking layer 1333a, electron generating layer 141, hole generating layer 142, hole transport layer 1322b, electron blocking layer 1323b, light-emitting layer 131B-b, hole blocking layer 1333b, electron transport layer 1332, electron injection layer 1331, and cathode 12 in the embodiment and the comparative example are all the same, which are 10nm, 19nm, 5nm, 15nm, 5nm, 18nm, 9nm, 19nm, 5nm, 15nm, 5nm, 35nm, 1nm, and 15nm, respectively.

[0498] The materials of the hole injection layer 1321, hole transport layer 1322a, hole blocking layer 1333a, electron generation layer 141, hole generation layer 142, hole transport layer 1322b, hole blocking layer 1333b, electron transport layer 1332, electron injection layer 1331, and cathode 12 in the embodiment and the comparative example are the same. Among them, the material of the anode 11 is indium tin oxide (ITO); the material of the hole injection layer 1321 is a mixed material obtained by mixing a hole transport material (the structure is shown in the aforementioned structural formula (HTL)) and a hole injection material (the structure is shown in the aforementioned structural formula (HIL)) in a mass ratio of 95:5; the materials of the hole transport layer 1322a and the hole transport layer 1322b are the same, and the structures are shown in the aforementioned structural formula (HTL); the hole blocking layer

[0499] The materials of 1333a and the hole blocking layer 1333b are the same, and their structures are as shown in the aforementioned structural formula (HBL); the material of the electron transport layer 1332 is a mixed material obtained by mixing a first electron transport material (structure as shown in the aforementioned structural formula (ETL)) and a second electron transport material (structure as shown in the aforementioned structural formula (LiQ)) in a mass ratio of 1:1; the material of the electron injection layer 1331 is ytterbium; the electron generating layer 141 is a mixed material obtained by mixing an electron generating material (structure as shown in the following formula (N-CGL)) and ytterbium in a mass ratio of 99:1; the material of the hole generating layer 142 is a mixed material obtained by mixing a hole generating material (structure as shown in the aforementioned structural formula (HTL)) and a hole injection material (structure as shown in the aforementioned structural formula (HIL)) in a mass ratio of 95:5; the material of the cathode 12 is a magnesium-silver alloy (Mg:Ag=1:9).

[0500]

[0501] It should be noted that (N-CGL) in the above structural formula is a synonym for the structural formula and is not a part of the structural formula.

[0502] The materials of the electron blocking layer 1323a, the light-emitting layer 131B-a, the electron blocking layer 1323b, and the light-emitting layer 131B-b of the first light-emitting device 101 of the embodiment and the comparative example are described below.

[0503] In Example 10, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a guest material D, the structure of the host material H is shown in (H-4); the structure of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structure of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-13).

[0504] In Example 11, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a guest material D, the structure of the host material H is shown in (H-5); the structure of the guest material D is shown in (D-6). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structure of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-7).

[0505] In Example 12, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a guest material D, and the structural formula of the host material H is shown in (H-4); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-18).

[0506] In Example 13, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a guest material D, and the structural formula of the host material H is shown in (H-5); the structural formula of the guest material D is shown in (D-6). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-20).

[0507] In Example 14, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a guest material D, and the structural formula of the host material H is shown in (H-5); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the host material H and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (R-G1).

[0508] In Example 15, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a comparative host material and a comparative guest material, the structural formula of the comparative host material is shown in (RH); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the comparative host material and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-13).

[0509] In Example 16, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a host material H and a comparative guest material, the structural formula of the host material H is shown in (H-4); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the host material H and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (R-G1).

[0510] In Example 17, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a comparative host material and a guest material D, the structural formula of the comparative host material is shown in (RH); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the comparative host material and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (R-G1).

[0511] In Example 18, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a comparative host material and a guest material D, the structural formula of the comparative host material is shown in (RH); the structural formula of the guest material D is shown in (D-4). Moreover, the mass ratio between the comparative host material and the guest material D is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (G1-18).

[0512] In Comparative Example 2, the light-emitting layer 131B-a and the light-emitting layer 131B-b include a comparative host material and a comparative guest material, the structural formula of the comparative host material is shown in (RH); the structural formula of the comparative guest material is shown in (RD). Moreover, the mass ratio between the comparative host material and the comparative guest material is 97:3. The structural formula of the material of the electron blocking layer 1323a and the electron blocking layer 1323b is shown in (R-G1).

[0513] In order to more clearly describe the differences in the structural formulas of the main material, guest material and the material of the electron blocking layer 1323 used in the embodiments and comparative examples, the following Table 6 is used to more clearly show the structural formulas of the main material, guest material and the material of the electron blocking layer 1323 used in the embodiments and comparative examples.

[0514] Table 6

[0515]

[0516]

[0517] It should be noted that "Ax" in Table 6 refers to the corresponding structural formula Ax. For example, the sub-grid content corresponding to the main material H in Example 10 is "H-4", which means that the structural formula of the main material H in the light-emitting layer 131B-a and the light-emitting layer 131B-b of Example 10 is shown as (H-4). Among them, the structural formulas represented by Hx, Dx, G1-x (x is a positive integer), RH, RD, and R-G1 refer to the above content and are not repeated here.

[0518] For the overlap rate of the HOMO state density of the above-mentioned main material H, guest material D, and first functional material G1, the absolute value of the difference between the electron reorganization energy and the hole reorganization energy, the thermal decomposition temperature Td, and the dipole moment data, please refer to the first group of experimental examples and will not be repeated here.

[0519] Based on the above materials, the voltage (V), current efficiency (cd / A), and device life of the first light emitting device 101 of Examples 10 to 18 and Comparative Example 2 were tested. The data results of voltage (V), current efficiency (cd / A), and device life are based on Comparative Example 1, and the test results are shown in Table 7 below. The device life is characterized by the parameter LT95.

[0520] Table 7

[0521] Voltage efficiency Device life Example 10 96.1％ 105.3％ 132.6％ Embodiment 11 97.3％ 104.2％ 141.9％ Example 12 96.3％ 103.6％ 129.8％ Embodiment 13 97.2％ 106.2％ 137.3％ Embodiment 14 100.3％ 105.0％ 103.3％ Embodiment 15 98.7％ 102.0％ 102.6％ Example 16 98.5％ 102.0％ 101.5％ Embodiment 17 99.6％ 99.0％ 101.9％ Embodiment 18 99.4％ 101.0％ 102.4％ Comparative Example 2 100％ 100％ 100％

[0522] As can be seen from Table 7, compared with Comparative Example 2, the device lifespans of Examples 10 to 13 are in the range of 129.8% to 141.9%, which are relatively high. This is because in the first light-emitting device 101 of Examples 10 to 13, the host material H, the guest material D of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and the materials of the electron blocking layer 1323a and the electron blocking layer 1323b (i.e., the first functional material) are all deuterated materials, while in Comparative Example 2, the comparative host material RH, the comparative guest material RD of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and the comparative first functional material R-G1 of the electron blocking layer 1323a and the electron blocking layer 1323b are all materials that do not contain deuterium atoms. Since the deuterated material has a relatively high bond dissociation energy, the stability of the material can be improved. When the main material H, the guest material D of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and the materials of the electron blocking layer 1323a and the electron blocking layer 1323b (i.e., the first functional material) are all deuterated materials, the material of the first light-emitting device 101 contains relatively more deuterium atoms, the stability of the three materials is improved, and under the synergistic effect of the three deuterated materials, the first light-emitting device 101 can exhibit a relatively excellent device life.

[0523] Compared with Comparative Example 2, as shown in Table 7, the device efficiencies of Examples 10 to 13 are in the range of 103.6% to 106.2%, which are relatively high. This is because in the first light-emitting device 101 of Examples 10 to 13, the host material H, the guest material D of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and the materials of the electron blocking layer 1323a and the electron blocking layer 1323b (i.e., the first functional material) are all deuterated materials, while in Comparative Example 2, the comparative host material RH, the comparative guest material RD of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and the comparative first functional material R-G1 of the electron blocking layer 1323a and the electron blocking layer 1323b are all materials that do not contain deuterium atoms. When the host material H and the guest material D are deuterated materials, the molecular vibration is relatively small, so that the quantum efficiency loss caused by the molecular vibration of the host material H and the guest material D is relatively small, and the efficiency of the first light-emitting device 101 is relatively high.

[0524] Compared with Comparative Example 2, Example 14, Example 16, and Example 17 have relatively high device lifespans, as shown in Table 7. This is because in the first light-emitting device 101 of Example 14, Example 16, and Example 17, the main material H of the light-emitting layer 131B-a and the light-emitting layer 131B-b, and / or the guest material D are all deuterated materials, while in Comparative Example 1, the comparative main material RH and the comparative guest material RD of the light-emitting layer 131B-a and the light-emitting layer 131B-b are all materials that do not contain deuterium atoms. Among them, the main material or the comparative main material is the position where high-energy excitons are produced by compounding, and the guest material or the comparative guest material is a material that receives the energy transmitted by the main material or the comparative main material and radiates light. Since the deuterated material has a relatively high bond dissociation energy, the electrical stability of the material can be improved. When the main material H and / or the guest material D of the light-emitting layer 131B-a and the light-emitting layer 131B-b are both deuterated materials, the main material H and / or the guest material D have relatively high electrical stability, which can improve the tolerance to high-energy excitons and high-energy intermediates of the TTA effect, so that the first light-emitting device 101 exhibits a relatively excellent device life.

[0525] Compared with Comparative Example 2, Example 15 and Example 18, please refer to Table 7, the device life of Example 15 and Example 18 is relatively high. This is because in the first light-emitting device 101 of Example 15 and Example 18, the material of the electron blocking layer 1323a and the electron blocking layer 1323b (i.e., the first functional material) is a deuterated material, while in Comparative Example 1, the material of the electron blocking layer 1323a and the electron blocking layer 1323b (i.e., the first functional material for comparison) is a material that does not contain deuterium atoms. Since the deuterated material has a relatively high bond dissociation energy, the electrical stability of the material can be improved. When the material of the electron blocking layer 1323a and the electron blocking layer 1323b is a deuterated material, the material of the two electron blocking layers has a relatively high electrical stability, which can improve the tolerance to carriers (electrons or holes) and excitons, so that the first light-emitting device 101 exhibits a relatively excellent device life.

[0526] As shown in Table 7, the device efficiencies of Examples 15 and 18 are relatively high compared with Comparative Example 2. This is because in the first light-emitting devices 101 of Examples 15 and 18, the materials of the electron blocking layers 1323a and 1323b (i.e., the first functional material) are selected from the structure shown in Formula (III) or Formula (IV), while in Comparative Example 1, the materials of the electron blocking layers 1323a and 1323b (i.e., the first functional material for comparison) do not conform to the structure shown in Formula (III) or Formula (IV). Since the structure represented by general formula (III) or general formula (IV) contains a carbazole group, a dibenzofuran group, a dibenzothiophene group, a fluorene group or a spirofluorene group, the triplet energy level of the first functional material can be relatively high, and the difference between the triplet energy level of the first functional material and the triplet energy level of the main material can be relatively large; in this way, after the holes and electrons recombine to form triplet excitons on the main material, the triplet excitons transferred from the main material to the first functional material are relatively small, so that the triplet excitons can be bound in the light-emitting layer 131 (for example, bound to the main material), the triplet exciton concentration in the light-emitting layer 131 can be increased, the TTA effect can be enhanced, the TTA effect can be fully utilized, and the efficiency of the first light-emitting device 101 can be improved.

[0527] It can be seen from the above embodiments and comparative examples that the present disclosure can improve the efficiency of the stacked light-emitting device 100 (for example, the first light-emitting device 101) and the device life of the stacked light-emitting device 100 (for example, the first light-emitting device 101) by setting the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material to be greater than 0% and less than or equal to 90%. Moreover, by setting the host material H to be selected from any one of the structures shown in the general formula (I), the guest material D to be selected from any one of the structures shown in the general formula (II), and the first functional material G1 to be selected from any one of the structures shown in the general formula (III) or the general formula (IV), the efficiency of the stacked light-emitting device 100 (for example, the first light-emitting device 101) can be further improved, and the device life of the stacked light-emitting device 100 (for example, the first light-emitting device 101) can be improved.

[0528] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be thought of by any person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A light emitting device, characterized in that: include: A cathode and an anode disposed opposite to each other, and at least one light emitting unit disposed between the cathode and the anode; The light-emitting unit comprises: a light-emitting layer and a first type of functional layer arranged on a side of the light-emitting layer close to the anode; the first type of functional layer comprises a first sub-functional layer and a second sub-functional layer; the material of the first sub-functional layer comprises a first functional material, and the material of the second sub-functional layer comprises a second functional material; The overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%.

2. The light emitting device according to claim 1, characterized in that: The first sub-functional layer is in contact with the light-emitting layer; the material of the light-emitting layer includes a host material; The overlap rate of the HOMO state density of the first functional material and the HOMO state density of the main material is greater than 0% and less than or equal to 90%.

3. The light emitting device according to claim 2, characterized in that: The material of the light-emitting layer further includes a guest material; at least one of the host material, the guest material and the first functional material is a deuterated material.

4. The light emitting device according to claim 2, characterized in that: The absolute value of the difference between the electron reorganization energy and the hole reorganization energy of the host material is less than or equal to 0.1 eV; and / or, The hole mobility of the host material is greater than the electron mobility of the host material.

5. The light emitting device according to claim 1, characterized in that: The dipole moment of the first functional material is greater than 0D.

6. The light emitting device according to claim 1, characterized in that: The lowest of the bond dissociation energies of the first functional material in the ground state is greater than or equal to 2.40 eV; and / or, The lowest bond dissociation energy of the first functional material in an anionic state is greater than or equal to 1.0 eV.

7. The light emitting device according to claim 3, characterized in that: The lowest of the bond dissociation energies of the host material in the ground state is greater than or equal to 1.50 eV; and / or, The lowest of the bond dissociation energies of the guest material in the ground state is greater than or equal to 1.50 eV.

8. The light emitting device according to claim 3, characterized in that: The triplet energy level of the host material is smaller than the triplet energy level of the guest material; and / or The singlet energy level of the host material is greater than the singlet energy level of the guest material.

9. The light emitting device according to claim 2, characterized in that: The light-emitting unit further comprises: a second type of functional layer disposed on a side of the light-emitting layer close to the cathode; the second type of functional layer comprises a third sub-functional layer, the third sub-functional layer is in contact with the light-emitting layer; the material of the third sub-functional layer comprises a third functional material; Wherein, the triplet energy level of the host material is smaller than the triplet energy level of the third functional material; and / or, The triplet energy level of the host material is smaller than the triplet energy level of the first functional material.

10. The light emitting device according to any one of claims 2 to 4 and 7 to 9, characterized in that: The main material is selected from any one of the structures shown in the following general formula (I); wherein R1, R2, R3, R4, R5, R6, R7 and R8 are the same or different and are independently selected from any one of hydrogen, deuterium, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted diarylamino, substituted or unsubstituted siloxane and substituted or unsubstituted silyl; L1 and L2 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group and a substituted or unsubstituted heteroarylene group; Ar1 and Ar2 are the same or different and are independently selected from substituted or unsubstituted aryl groups; At least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium.

11. The light emitting device according to claim 10, characterized in that: In the case where the host material is a deuterated material, the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

12. The light emitting device according to any one of claims 3, 7 and 8, characterized in that: The guest material is selected from any one of the structures shown in the following general formula (II); wherein A, E and F are the same or different and are independently selected from any one of a substituted or unsubstituted aromatic ring, a substituted or unsubstituted heteroaromatic ring and a substituted or unsubstituted cycloalkane ring; in the case where A, E and F are selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, the substituent may be linked to an adjacent substituent to form a substituted or unsubstituted ring; X1 and X2 are the same or different and are independently selected from O, N(R a ) and C(R b R c ) R a , R b and R c are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl and substituted or unsubstituted heterocyclic group; At least one of A, E and F contains deuterium.

13. The light emitting device according to claim 12, characterized in that: Among A, E and F, at least one of the substituents includes a tert-butyl group.

14. The light emitting device according to claim 12, characterized in that: In the case where the guest material is a deuterated material, the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

15. The light emitting device according to claim 1, characterized in that: The first functional material is selected from any one of the structures shown in the following general formula (III); Wherein, Z is selected from O, S, N (R d ) and C(R e R f ) R d , R e and R f are the same or different and are independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl; L3 and L4 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group and a substituted or unsubstituted heteroarylene group; e and f are the same or different and are independently selected from any one of 1, 2, 3 and 4; Ar3, Ar4, Ar5 and Ar6 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S; p and q are the same or different and are independently selected from any one of 0, 1 and 2; and the sum of p and q is greater than or equal to 1 and less than or equal to 2.

16. The light emitting device according to claim 15, characterized in that: The first functional material is selected from any one of the structures shown in the following general formula (III-A); wherein g and h are the same or different and are independently selected from any one of 0, 1, 2 and 3.

17. The light emitting device according to claim 1, characterized in that: The first functional material is selected from any one of the structures shown in the following general formula (IV); Wherein, L5 is selected from any one of a single bond and a substituted or unsubstituted C6-C60 arylene group; Ar7 and Ar8 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S; R9 and R 10 The same or different, independently selected from any one of hydrogen, deuterium, halogen, cyano, nitro, amino, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C3-C60 cycloalkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C6-C60 aryl and substituted or unsubstituted C2-C60 heteroaryl; or may be connected with adjacent substituents to form a substituted or unsubstituted ring; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S; m and n are the same or different and are independently selected from any one of 1, 2, 3 and 4; At least one R9 is deuterium; At least one R 10 For deuterium.

18. The light emitting device according to any one of claims 1 to 9 and 15 to 17, characterized in that: In the case where the first functional material is a deuterated material, the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

19. The light emitting device according to claim 18, characterized in that: The light emitting device comprises at least two light emitting units, and the at least two light emitting units are stacked; The light emitting device further comprises a charge generating layer located between two adjacent light emitting units; the charge generating layer comprises a hole generating layer and an electron generating layer which are stacked; the electron generating layer is closer to the anode than the hole generating layer.

20. The light emitting device according to claim 18, characterized in that: The structural formula of the second functional material is as follows:

21. The light emitting device according to claim 18, characterized in that: The light emitting device is configured to emit light of a first wavelength, and the light of the first wavelength is blue light.

22. A display panel, characterized in that: comprising a plurality of light emitting devices according to any one of claims 1 to 21; It also includes: a plurality of pixel driving circuits, wherein the pixel driving circuits are electrically connected to the light emitting devices and are used to drive the light emitting devices to emit light.

23. A display panel, characterized in that: include: substrate; A plurality of light emitting devices are disposed on the substrate and arranged along a first direction, wherein the first direction is parallel to the plane where the substrate is located; The plurality of light emitting devices include at least one first light emitting device, at least one second light emitting device, and at least one third light emitting device, wherein the first light emitting device is configured to emit blue light; The second light emitting device is configured to emit green light; The third light emitting device is configured to emit red light; Each of the plurality of light-emitting devices comprises a cathode and an anode arranged opposite to each other, and at least one light-emitting unit arranged between the cathode and the anode; the light-emitting unit comprises a light-emitting layer; the number of light-emitting units included in each of the plurality of light-emitting devices is n, and n is a positive integer greater than or equal to 1; The thickness of the light-emitting layer of the Nth light-emitting unit of the third light-emitting device is greater than the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device; the thickness of the light-emitting layer of the Nth light-emitting unit of the second light-emitting device is greater than the thickness of the light-emitting layer of the Nth light-emitting unit of the first light-emitting device, wherein N is a positive integer less than or equal to n.

24. The display panel according to claim 23, characterized in that: A difference between a thickness of a light-emitting layer of an N-th light-emitting unit of the third light-emitting device and a thickness of a light-emitting layer of an N-th light-emitting unit of the first light-emitting device is a first thickness difference; A difference between a thickness of a light-emitting layer of an N-th light-emitting unit of the second light-emitting device and a thickness of a light-emitting layer of an N-th light-emitting unit of the first light-emitting device is a second thickness difference; A difference between a thickness of a light-emitting layer of an Nth light-emitting unit of the third light-emitting device and a thickness of a light-emitting layer of an Nth light-emitting unit of the second light-emitting device is a third thickness difference; Wherein, a ratio between the first thickness difference and the second thickness difference is greater than or equal to 1.5 and less than or equal to 2; A ratio between the third thickness difference and the second thickness difference is greater than or equal to 1 and less than or equal to 1.

5.

25. The display panel according to claim 24, characterized in that: The light-emitting unit further comprises a first type of functional layer disposed on a side of the light-emitting layer close to the anode; the first type of functional layer comprises a first sub-functional layer in contact with the light-emitting layer; The difference between the thickness of the first subfunctional layer of the Nth light-emitting unit of the third light-emitting device and the thickness of the first subfunctional layer of the Nth light-emitting unit of the first light-emitting device is a fourth thickness difference; the difference between the thickness of the first subfunctional layer of the Nth light-emitting unit of the second light-emitting device and the thickness of the first subfunctional layer of the Nth light-emitting unit of the first light-emitting device is a fifth thickness difference; A ratio between the fourth thickness difference and the fifth thickness difference is greater than or equal to 1.1 and less than or equal to 1.

5.

26. The display panel according to claim 25, characterized in that: The light-emitting unit also includes a second type of functional layer arranged on a side of the light-emitting layer close to the cathode; a ratio between a thickness of the first type of functional layer and a thickness of the second type of functional layer is greater than or equal to 1 and less than or equal to 5.

27. The display panel according to claim 23, characterized in that: The material of the light-emitting layer includes a guest material, and the guest material is configured to emit light of a set wavelength; The relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is greater than or equal to 650 and less than or equal to 1300; and / or, The relative molecular weight of the guest material of the light-emitting layer of the second light-emitting device is greater than or equal to 700 and less than or equal to 1400; and / or, The relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device is greater than or equal to 700 and less than or equal to 1500.

28. The display panel according to claim 27, characterized in that: The absolute value of the difference between the relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is less than or equal to 600; and / or, An absolute value of a difference between a relative molecular weight of a guest material in the light-emitting layer of the second light-emitting device and a relative molecular weight of a guest material in the light-emitting layer of the first light-emitting device is less than or equal to 500.

29. The display panel according to claim 27, characterized in that: The difference between the relative molecular weight of the guest material of the light-emitting layer of the third light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is a first relative molecular weight difference; The difference between the relative molecular weight of the guest material of the light-emitting layer of the second light-emitting device and the relative molecular weight of the guest material of the light-emitting layer of the first light-emitting device is a second relative molecular weight difference; The ratio of the absolute value of the first relative molecular weight difference to the absolute value of the second relative molecular weight difference is greater than or equal to 0.5 and less than or equal to 6.

30. The display panel according to claim 25, characterized in that: The optical path of the light in the light-emitting layer of the light-emitting unit close to the anode of the first light-emitting device and the first type of functional layer is the first optical path; the optical path of the light in the light-emitting layer of the light-emitting unit close to the anode of the second light-emitting device and the first type of functional layer is the second optical path; the optical path of the light in the light-emitting layer of the light-emitting unit close to the anode of the third light-emitting device and the first type of functional layer is the third optical path; Among them, the ratio between the third optical path and the second optical path is greater than or equal to 1.1 and less than or equal to 1.25; the ratio between the third optical path and the first optical path is greater than or equal to 1.25 and less than or equal to 1.45; the ratio between the second optical path and the first optical path is greater than or equal to 1.05 and less than or equal to 1.

25.

31. The display panel according to claim 23, characterized in that: The light emitting device comprises a first light emitting unit and a second light emitting unit; the first light emitting unit is closer to the anode than the second light emitting unit; A ratio of a thickness of the light-emitting layer of the first light-emitting unit to a thickness of the light-emitting layer of the second light-emitting unit is greater than or equal to 0.8 and less than or equal to 1.

5.

32. The display panel according to claim 31, characterized in that: In the case where the light-emitting unit includes a first type of functional layer and a second type of functional layer, the first type of functional layer further includes a second sub-functional layer and a fourth sub-functional layer, and the fourth sub-functional layer, the second sub-functional layer and the first sub-functional layer are sequentially arranged in a direction away from the anode; the second type of functional layer includes a third sub-functional layer, a fifth sub-functional layer and a sixth sub-functional layer; the sixth sub-functional layer, the fifth sub-functional layer and the third sub-functional layer are sequentially arranged in a direction away from the cathode; Among them, the sum of the thickness of the second sub-functional layer of the second light-emitting unit and the thickness of the fifth sub-functional layer is the first thickness sum, and the sum of the thickness of the second sub-functional layer of the first light-emitting unit and the thickness of the fifth sub-functional layer is the second thickness sum; the ratio between the first thickness sum and the second thickness sum is greater than or equal to 2 and less than or equal to 4.

33. The display panel according to claim 32, characterized in that: The sum of the thickness of the first sub-functional layer and the thickness of the second sub-functional layer of the second light-emitting unit is the third thickness sum, and the sum of the thickness of the first sub-functional layer and the thickness of the second sub-functional layer of the first light-emitting unit is the fourth thickness sum; the ratio of the third thickness sum to the fourth thickness sum is greater than or equal to 2 and less than or equal to 5.

34. The display panel according to claim 32, characterized in that: The sum of the thickness of the third sub-functional layer and the thickness of the fifth sub-functional layer of the second light-emitting unit is the fifth thickness sum, and the sum of the thickness of the third sub-functional layer and the thickness of the fifth sub-functional layer of the first light-emitting unit is the sixth thickness sum; the ratio of the fifth thickness sum to the sixth thickness sum is greater than or equal to 1.5 and less than or equal to 3.

35. The display panel according to any one of claims 25 to 34, characterized in that: In the case where the first type of functional layer further includes a second sub-functional layer, the material of the light-emitting layer includes a host material and a guest material; the material of the first sub-functional layer includes a first functional material, and the material of the second sub-functional layer includes a second functional material; wherein the overlap rate of the HOMO state density of the first functional material and the HOMO state density of the second functional material is greater than 0% and less than or equal to 90%; and / or, The overlap rate of the HOMO state density of the first functional material and the HOMO state density of the main material is greater than 0% and less than or equal to 90%.

36. The display panel according to claim 35, characterized in that: At least one of the host material, the guest material and the first functional material is a deuterated material.

37. The display panel according to claim 35, characterized in that: The absolute value of the difference between the electron reorganization energy and the hole reorganization energy of the host material is less than or equal to 0.1 eV; and / or, The hole mobility of the host material is greater than the electron mobility of the host material.

38. The display panel according to claim 35, characterized in that: The dipole moment of the first functional material is greater than 0D.

39. The display panel according to claim 35, characterized in that: The lowest of the bond dissociation energies of the first functional material in the ground state is greater than or equal to 2.40 eV; and / or, The lowest bond dissociation energy of the first functional material in an anionic state is greater than or equal to 1.0 eV.

40. The display panel according to claim 35, characterized in that The lowest of the bond dissociation energies of the host material in the ground state is greater than or equal to 1.50 eV; and / or, The lowest of the bond dissociation energies of the guest material in the ground state is greater than or equal to 1.50 eV.

41. The display panel according to claim 35, characterized in that: The triplet energy level of the host material is smaller than the triplet energy level of the guest material; and / or The singlet energy level of the host material is greater than the singlet energy level of the guest material.

42. The display panel according to claim 35, characterized in that: When the light-emitting unit further includes a third sub-functional layer, the third sub-functional layer is in contact with the light-emitting layer; and the material of the third sub-functional layer includes a third functional material; Wherein, the triplet energy level of the host material is smaller than the triplet energy level of the third functional material; and / or, The triplet energy level of the host material is smaller than the triplet energy level of the first functional material.

43. The display panel according to claim 35, characterized in that The main material is selected from any one of the structures shown in the following general formula (I); wherein R1, R2, R3, R4, R5, R6, R7 and R8 are the same or different and are independently selected from any one of hydrogen, deuterium, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted aryloxy, substituted or unsubstituted diarylamino, substituted or unsubstituted siloxane and substituted or unsubstituted silyl; L1 and L2 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group and a substituted or unsubstituted heteroarylene group; Ar1 and Ar2 are the same or different and are independently selected from substituted or unsubstituted aryl groups; At least one of R1, R2, R3, R4, R5, R6, R7, R8, L1, L2, Ar1 and Ar2 contains deuterium.

44. The display panel according to claim 35, characterized in that: In the case where the host material is a deuterated material, the mass fraction of deuterium in the host material is greater than or equal to 1.0% and less than or equal to 4.9%.

45. The display panel according to claim 35, characterized in that: The guest material is selected from any one of the structures shown in the following general formula (II); wherein A, E and F are the same or different and are independently selected from any one of a substituted or unsubstituted aromatic ring, a substituted or unsubstituted heteroaromatic ring and a substituted or unsubstituted cycloalkane ring; in the case where A, E and F are selected from any one of a substituted aromatic ring, a substituted heteroaromatic ring and a substituted cycloalkane ring, the substituent may be linked to an adjacent substituent to form a substituted or unsubstituted ring; X1 and X2 are the same or different and are independently selected from O, N(R a ) and C(R b R c ) R a , R b and R c are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl and substituted or unsubstituted heterocyclic group; At least one of A, E and F contains deuterium.

46. ​​The display panel according to claim 45, characterized in that: Among A, E and F, at least one of the substituents includes a tert-butyl group.

47. The display panel according to claim 45, characterized in that: In the case where the guest material is a deuterated material, the mass fraction of deuterium in the guest material is greater than or equal to 0.1% and less than or equal to 8.5%.

48. The display panel according to claim 35, characterized in that: The first functional material is selected from any one of the structures shown in the following general formula (III); Wherein, Z is selected from O, S, N (R d ) and C(R e R f ) R d , R e and R f are the same or different and are independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl; L3 and L4 are the same or different and are independently selected from any one of a single bond, a substituted or unsubstituted arylene group and a substituted or unsubstituted heteroarylene group; e and f are the same or different and are independently selected from any one of 1, 2, 3 and 4; Ar3, Ar4, Ar5 and Ar6 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S; p and q are the same or different and are independently selected from any one of 0, 1 and 2; and the sum of p and q is greater than or equal to 1 and less than or equal to 2.

49. The display panel according to claim 48, characterized in that The first functional material is selected from any one of the structures shown in the following general formula (III-A); wherein g and h are the same or different and are independently selected from any one of 0, 1, 2 and 3.

50. The display panel according to claim 35, characterized in that: The first functional material is selected from any one of the structures shown in the following general formula (IV); Wherein, L5 is selected from any one of a single bond and a substituted or unsubstituted C6-C60 arylene group; Ar7 and Ar8 are the same or different and are independently selected from any one of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C2-C60 heteroaryl group; the C2-C60 heteroaryl group includes at least one heteroatom, and the heteroatom includes N, O and S; R9 and R 10 The same or different, independently selected from any one of hydrogen, deuterium, halogen, cyano, nitro, amino, substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C3-C60 cycloalkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C6-C60 aryl and substituted or unsubstituted C2-C60 heteroaryl; or may be connected with adjacent substituents to form a substituted or unsubstituted ring; the C2-C60 heteroaryl includes at least one heteroatom, and the heteroatom includes N, O and S; m and n are the same or different and are independently selected from any one of 1, 2, 3 and 4; At least one R9 is deuterium; At least one R 10 For deuterium.

51. The display panel according to claim 35, characterized in that: In the case where the first functional material is a deuterated material, the mass fraction of deuterium in the first functional material is greater than or equal to 0.15% and less than or equal to 5.50%.

52. The display panel according to claim 35, characterized in that: The light emitting device comprises at least two light emitting units, and the at least two light emitting units are stacked; The light emitting device further comprises a charge generating layer located between two adjacent light emitting units; the charge generating layer comprises a hole generating layer and an electron generating layer which are stacked; the electron generating layer is closer to the anode than the hole generating layer.

53. The display panel according to claim 35, characterized in that: The structural formula of the second functional material is as follows:

54. The display panel according to claim 42, characterized in that: The host material is the host material of the light-emitting layer of the first light-emitting device; the guest material is the guest material of the light-emitting layer of the first light-emitting device; the first functional material is the material of the first sub-functional layer of the first light-emitting device; the second functional material is the material of the second sub-functional layer of the first light-emitting device; In the case where the light-emitting unit further includes a third sub-functional layer, the third functional material is the material of the third sub-functional layer of the first light-emitting device.

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