Light-emitting device, display panel and display device

Abstract

The embodiment of the invention provides a light-emitting device, a display panel and a display device, relates to the technical field of display, and aims to solve the problem of display difference under different gray scales. The light emitting device includes first and second electrodes and at least one light emitting unit. The light-emitting layer of at least one light-emitting unit includes a first host material, a second host material, and a first light-emitting material. Photons emitted by the first luminescent material comprise photons emitted by energy obtained through fluorescence resonance energy transfer of the first host material and / or the second host material, and photons emitted by excitons formed by composite electrons and holes; the ratio of the number of photons emitted by the first luminescent material to the number of photons emitted by the luminescent layer is greater than 80%; and the ratio of the number of photons emitted by energy obtained by the first luminescent material through fluorescence resonance energy transfer of the first host material and / or the second host material to the number of photons emitted by the first luminescent material is greater than 60%. The light-emitting device is used for displaying images.

Description

Light-emitting device, display panel, and display apparatus Technical Field

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

[0003] Summary of the Invention

[0004] In one aspect, a light-emitting device is provided. The light-emitting device includes a first electrode and a second electrode stacked together and at least one light-emitting unit disposed between the first electrode and the second electrode. The at least one light-emitting unit includes a light-emitting layer, and the light-emitting layer includes: a first host material, a second host material, and a first light-emitting material. The photons emitted by the first light-emitting material include: photons emitted by energy obtained through fluorescence resonance energy transfer from the first host material and / or the second host material, and photons emitted by excitons formed by recombining electrons and holes; the ratio of the number of photons emitted by the first light-emitting material to the number of photons emitted by the light-emitting layer is greater than 80%; and the ratio of the number of photons emitted by the first light-emitting material from energy obtained through fluorescence resonance energy transfer from the first host material and / or the second host material to the number of photons emitted by the first light-emitting material is greater than 60%.

[0005] In some embodiments, the mass ratio of the first light-emitting material in the light-emitting layer is less than or equal to 5% and greater than or equal to 0.5%.

[0006] In other embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level of the first luminescent material and the larger of the highest occupied molecular orbital energy level of the first host material and the highest occupied molecular orbital energy level of the second host material is less than or equal to 0.25 eV.

[0007] In some further embodiments, the singlet energy level of the first host material is greater than the singlet energy level of the first light-emitting material; the singlet energy level of the second host material is greater than the singlet energy level of the first light-emitting material; the triplet energy level of the first host material is greater than the triplet energy level of the first light-emitting material; and the triplet energy level of the second host material is greater than the triplet energy level of the first light-emitting material.

[0008] In some further embodiments, the lowest occupied molecular orbital energy level of the first luminescent material is greater than the lower of the lowest occupied molecular orbital energy level of the first host material and the lowest occupied molecular orbital energy level of the second host material.

[0009] In some other embodiments, the hole mobility of the first host material is greater than the electron mobility of the first host material; the electron mobility of the second host material is greater than the hole mobility of the second host material; and the ratio of the hole mobility of the first host material to the electron mobility of the second host material is greater than or equal to 0.1.

[0010] In some other embodiments, the electron mobility of the first host material is greater than the hole mobility of the first host material; the hole mobility of the second host material is greater than the electron mobility of the second host material; and the ratio of the hole mobility of the second host material to the electron mobility of the first host material is greater than or equal to 0.1.

[0011] In some further embodiments, at least one of the internal quantum efficiency of the first host material and the internal quantum efficiency of the second host material is greater than or equal to 30%.

[0012] In some other embodiments, the ratio of the mass fraction of the first host material in the light-emitting layer to the mass fraction of the second host material in the light-emitting layer is greater than or equal to 0.25 and less than or equal to 4.

[0013] In yet other embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level of the first host material and the highest occupied molecular orbital energy level of the second host material is less than or equal to 0.25 eV.

[0014] In some further embodiments, the first luminescent material is selected from any one of the structures shown in the following general formula I.

[0015] wherein X, Y and Z are the same or different and are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; the value of n is selected from any one of 1, 2, 3 and 4; A and E are the same or different and are independently selected from any one of a five-membered or six-membered carbocyclic ring, a five-membered or six-membered carboheterocyclic ring and a condensed ring; Ra, Rb, Rx, Ry, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0016] In some further embodiments, the first luminescent material is selected from any one of the structures shown in the following general formula II.

[0017] wherein X, Y and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and Z is different from X and Y; A, E, F and G are the same or different and are independently selected from any one of a five-membered or six-membered carbocycle, a five-membered or six-membered carboheterocycle and a condensed ring, and A, E, F and G are not six-membered carbocycles at the same time; when G is a six-membered carbocycle, F is not a six-membered carbocycle or does not exist; Ra, Rb, Rc, Rd, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5~C50 aryl and substituted or unsubstituted C1~C50 alkyl.

[0018] In some further embodiments, the first luminescent material is selected from any one of the structures shown in the following general formula III.

[0019] wherein X, Y and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and X and Y are the same or different, and Z is different from X and Y; A is selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; Ra, Rx, Ry, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0020] In some further embodiments, the first luminescent material is selected from any one of the structures shown in the following general formula IV.

[0021] wherein X, Y, Z and X1 are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond, and when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different; A and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A and E are not both six-membered carbocyclic rings; Ra, Rb, Rx, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0022] In some further embodiments, the first luminescent material is selected from any one of the structures shown in the following general formula V.

[0023] wherein X, Y, Z, X1 and Y1 are each selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and, when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different; Y1 and X are different; A, E and J are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A, E and J are not all six-membered carbocyclic rings; Ra, Rb, Rc, Rx, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0024] In some other embodiments, the molecular weight of the first luminescent material is less than or equal to 1250.

[0025] In some further embodiments, at least one light-emitting layer further comprises a second light-emitting material; the singlet energy level of the second light-emitting material is smaller than the singlet energy level of the first light-emitting material; and the triplet energy level of the second light-emitting material is greater than the triplet energy level of the first light-emitting material.

[0026] In some other embodiments, the mass ratio of the second light-emitting material in the light-emitting layer is less than or equal to 5% and greater than or equal to 0.1%.

[0027] In another aspect, a display panel is provided, comprising: a light-emitting device as described in any one of the above embodiments and a driving circuit, wherein the driving circuit is configured to drive the light-emitting device to emit light.

[0028] In another aspect, a display device is provided. The display device comprises the display panel and a driver chip according to any of the above embodiments. The driver chip is used to drive the display panel to display. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the technical solutions of the present disclosure, the following briefly introduces the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure, and those skilled in the art can also derive other drawings based on these drawings. Furthermore, the drawings described below are schematic diagrams and are not intended to limit the actual dimensions of the products, actual processes of the methods, actual timing of signals, and the like involved in the embodiments of the present disclosure.

[0030] FIG1 is a structural diagram of a display device according to some embodiments of the present disclosure;

[0031] FIG2 is a structural diagram of a display panel provided according to some embodiments of the present disclosure;

[0032] FIG3 is a structural diagram of a light emitting device provided according to some embodiments of the present disclosure;

[0033] FIG4 is another structural diagram of a light emitting device according to some embodiments of the present disclosure;

[0034] FIG5 is an emission spectrum diagram of a light-emitting device provided according to some embodiments of the present disclosure;

[0035] FIG6 is another emission spectrum diagram of a light-emitting device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0036] 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 embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0037] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and 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" are intended to indicate that the particular 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 particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0038] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, 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.

[0039] “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.

[0040] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0041] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation 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).

[0042] 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 an acceptable deviation range, wherein the acceptable deviation range is as 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 the specific 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 can be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity can also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality can be, for example, that the difference between the two equals is less than or equal to 5% of either one.

[0043] It will be understood that when a layer or 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 therebetween.

[0044] Exemplary embodiments are described herein with reference to cross-sectional and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include deviations in shape 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 shape of regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0045] It should be noted that, for example, 11-1 in the drawings of the present disclosure indicates that component 11 belongs to component 1, and for example, 130B-130 indicates that blue light-emitting unit 130B belongs to light-emitting unit 130. Other similar numbers appearing in the drawings also follow the above description.

[0046] Referring to FIG. 1 , some embodiments of the present disclosure provide a display device 300 , which includes a display panel 200 .

[0047] In some examples, the display device 300 may be an OLED (Organic Light Emitting Diode) display device.

[0048] 1 , the display device 300 further includes a driver chip 310. The driver chip 310 is used to drive the display panel 200 to perform display.

[0049] 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 various functions such as taking pictures, recording videos, fingerprint recognition or face recognition.

[0050] The display device 300 described above can be any display device 300 that displays either motion (e.g., video) or fixed (e.g., still images) and text or images. More specifically, it is contemplated that the display device 300 of the embodiments described herein 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., speedometer displays, etc.), navigation systems, cockpit controls and / or displays, displays of camera views (e.g., displays of rearview 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.

[0051] In some embodiments, referring to FIG. 2 , the display panel 200 includes a display substrate 210 . The display substrate 210 includes an array layer 211 and a light-emitting functional layer 212 . The light-emitting functional layer 212 is located on one side of the array layer 211 . The array layer 211 includes a plurality of driving circuits 2111 . The light-emitting functional layer 212 includes a plurality of light-emitting devices 100 .

[0052] 2 , multiple driving circuits 2111 and multiple light emitting devices 100 may be coupled one-to-one. In other examples, one driving circuit 2111 may be coupled to multiple light emitting devices 100 , or multiple driving circuits 2111 may be coupled to one light emitting device 100 .

[0053] For example, in the display panel 200, the driving circuit 2111 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 driving circuit 2111. The light emitted by multiple light-emitting devices 100 cooperates with each other, thereby enabling the display panel 200 to achieve a display function.

[0054] In some implementations, OLED displays may exhibit greenish or reddish tints at low grayscales. This is because the OLED display's display is a mixture of red (R), green (G), and blue (B), and the current efficiency of these three colors has different roll-off trends at different grayscales, resulting in greenish or reddish tints at low grayscales.

[0055] In other implementations, the OLED display device may have a color cast problem at different grayscales during use. This is because the efficiency difference between low grayscales and high grayscales is too large, resulting in display differences at different grayscales.

[0056] Based on this, referring to FIG3 , some embodiments of the present disclosure provide a light-emitting device 100, comprising a first electrode 110 and a second electrode 120 stacked together, and at least one light-emitting unit 130 disposed between the first electrode 110 and the second electrode 120. The at least one light-emitting unit 130 includes a light-emitting layer 131, which comprises a first host material H1, a second host material H2, and a first light-emitting material D1. The photons emitted by the first light-emitting material D1 include photons emitted from energy obtained through fluorescence resonance energy transfer from the first host material H1 and / or the second host material H2, and photons emitted from excitons formed by the recombination of electrons and holes. The ratio of the number of photons emitted by the first light-emitting material D1 to the number of photons emitted by the light-emitting layer 131 is greater than 80%. Furthermore, the ratio of the number of photons emitted by the first light-emitting material D1 from energy obtained through fluorescence resonance energy transfer from the first host material H1 and / or the second host material H2 to the number of photons emitted by the first light-emitting material D1 is greater than 60%.

[0057] In some examples, referring to FIG3 , the second direction Y is arranged perpendicular to the first direction X. The first electrode 110 may be an anode, and the second electrode 120 may be a cathode. During operation, a voltage is applied to the first electrode 110 and the second electrode 120, respectively, to generate an electric field therebetween, which can drive the holes in the anode and the electrons in the cathode to recombine in the light-emitting unit 130, thereby emitting emitted light. The emitted light includes light emitted by photons emitted by the first light-emitting material D1; the photons emitted by the first light-emitting material D1 include photons emitted by energy obtained through fluorescence resonance energy transfer of the first host material H1 and / or the second host material H2, and photons emitted by excitons formed by the recombination of electrons and holes.

[0058] For example, in order to ensure that the light-emitting device 100 can effectively emit light, the first electrode 110 (anode) is made of a material with a high work function, such as a material with a work function greater than 6 eV; the second electrode 120 (cathode) is made of a material with a low work function, such as a material with a work function less than a set value, and the set value can range from 2.0 eV to 3.0 eV. In this way, the holes in the anode and the electrons in the cathode can effectively migrate to the light-emitting unit 130 under the drive of the electric field, thereby compounding and emitting light.

[0059] In some examples, the light-emitting device 100 is a bottom-emitting light-emitting device. The material of the first electrode 110 can be a transparent conductive metal oxide material to prevent the first electrode 110 from blocking light. For example, the material of the first electrode 110 can be indium tin oxide (ITO) or indium zinc oxide (IZO). The thickness of the first electrode 110 can be 80 nm to 200 nm. The average reflectivity of the material of the first electrode 110 in the visible light range can be 85% to 95%. The material of the second electrode 120 can be a metal material. For example, the material of the second electrode 120 can be magnesium, silver, aluminum, or a magnesium-silver alloy. When the material of the second electrode 120 is a magnesium-silver alloy, the mass ratio of magnesium to silver is 3:7 to 1:9. The process of forming the second electrode 120 is, for example, an evaporation process. The thickness of the second electrode 120 can be greater than or equal to 80 nm to ensure good reflectivity.

[0060] In other examples, the light-emitting device 100 is a top-emitting light-emitting device, and the material of the first electrode 110 can be a composite layer structure composed of a metal and a conductive metal oxide. For example, the material of the first electrode 110 can be a composite layer structure composed of silver / indium tin oxide or silver / indium zinc oxide. The thickness of the metal layer can be 80 nm to 100 nm, and the thickness of the conductive metal oxide can be 5 nm to 10 nm. The average reflectivity of the material of the first electrode 110 in the visible light region can be 85% to 95%. The material of the second electrode 120 can be a metal material, for example, magnesium, silver, aluminum, or a magnesium-silver alloy. When the material of the second electrode 120 is a magnesium-silver alloy, the mass ratio of magnesium to silver is 3:7 to 1:9. The process for forming the second electrode 120 is, for example, an evaporation process. The thickness of the second electrode 120 can be 10 nm to 20 nm. The transmittance of the material of the second electrode 120 at 530 nm is 50% to 60%.

[0061] In some embodiments, referring to FIG3 , in order to improve the luminous efficiency of the light-emitting device 100 , at least one of a hole injection layer 140 (HIL), a hole transport layer 150 (HTL), and an electron blocking layer 160 (EBL) is stacked between the first electrode 110 and the light-emitting unit 130 ; and at least one of an electron injection layer 170 (EIL), an electron transport layer 180 (ETL), and a hole blocking layer 190 (EBL) is stacked between the second electrode 120 and the light-emitting unit 130 . By setting up the film layers such as the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the electron injection layer 170, the electron transport layer 180, and the hole blocking layer 190, it is equivalent to setting up transition steps between the anode and the light-emitting unit 130 and between the cathode and the light-emitting unit 130, thereby reducing the potential barrier height that needs to be overcome for carrier transition, thereby making the luminescence efficiency higher.

[0062] Exemplarily, the hole injection layer 140 is configured to reduce the hole injection barrier and improve the hole injection efficiency; the hole injection layer 140 can be a single-layer film formed of a single material, and the material of the hole injection layer 140 is, for example, 11-hexacyano-1 (HAT-CN) or phthalocyanine blue (CuPc); the hole injection layer 140 can also be prepared by P-type doping of the hole transport material, such as doping 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ) in N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), or doping manganese trioxide (MnO3) in 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC); the doping concentration can be 0.5% to 10%. The thickness of the hole injection layer 140 may be 5 nm to 20 nm.

[0063] Exemplarily, the hole transport layer 150 is configured to transport holes. The material of the hole transport layer 150 can be a material with high hole mobility, such as a carbazole material. The hole transport layer 150 can be formed by an evaporation process. The highest occupied molecular orbital (HOMO) energy level of the hole transport layer 150 can be 5.2 eV to 5.6 eV. The thickness of the hole transport layer 150 can be 100 nm to 140 nm.

[0064] For example, the electron blocking layer 160 is configured to block electrons and excitons generated in the light emitting unit 130 ; the thickness of the electron blocking layer 160 may be 1 nm to 10 nm.

[0065] For example, the thickness of the electron injection layer 170 may be 0.5 nm to 2 nm.

[0066] For example, the thickness of the electron transport layer 180 may be 20 nm to 70 nm.

[0067] For example, the hole blocking layer 190 is configured to block holes and excitons generated in the electron transport layer 180 ; the thickness of the hole blocking layer 190 may be 2 nm to 10 nm.

[0068] Exemplarily, the thickness of the light-emitting unit 130 is 10 nm to 30 nm. The light-emitting layer 131 of the light-emitting unit 130 includes a first host material H1, a second host material H2, and a first light-emitting material D1. The doping ratio of the first host material H1 is greater than or equal to 50%, the doping ratio of the second host material H2 is greater than or equal to 5% and less than or equal to 50%, and the doping ratio of the first light-emitting material D1 is greater than or equal to 0.5% and less than or equal to 5%. The second host material H2 has a delayed fluorescence characteristic. The singlet energy level (S1(H2)) and the triplet energy level (T1(H2)) of the second host material H2 satisfy the following relationship: S1(H2)-T1(H2)≤0.2 eV. The luminous efficiency of the second host material H2 accounts for less than 10% of the total luminous efficiency of the light-emitting unit 130.

[0069] In some embodiments, referring to FIG3 , there are at least two light-emitting units 130, and the second electrode 120 stacked with each light-emitting unit 130 is a structure that is interconnected throughout the entire layer, i.e., the second electrode 120 may be a common electrode shared by multiple light-emitting units 130. The hole injection layer 140 stacked with each light-emitting unit 130 may also be a structure that is interconnected throughout the entire layer, i.e., the hole injection layer 140 may be a common film layer shared by multiple light-emitting units 130. The hole transport layer 150, electron blocking layer 160, hole blocking layer 190, electron injection layer 170, and electron transport layer 180 may also be common film layers shared by multiple light-emitting units 130.

[0070] In some embodiments, referring to FIG. 2 and FIG. 3 , the at least one light-emitting unit 130 includes three light-emitting units 130 . For example, the three light-emitting units 130 are a red light-emitting unit 130R, a green light-emitting unit 130G, and a blue light-emitting unit 130B. The red light-emitting unit 130R emits red light, the green light-emitting unit 130G emits green light, and the blue light-emitting unit 130B emits blue light. The three light-emitting units 130 are arranged along a second direction Y, which is perpendicular to the first direction X. By configuring the three light-emitting units 130 , the brightness (grayscale) of the light-emitting units 130 of different colors can be adjusted separately. By combining and superimposing colors, multiple colors can be displayed, thereby achieving full-color display on the display panel 200 .

[0071] In other embodiments, the at least two light-emitting units 130 include M light-emitting units 130, where M is a positive integer greater than three, and the M light-emitting units 130 are arranged along the second direction Y, and the second direction Y is perpendicular to the first direction X. For example, the number of red light-emitting units 130R is at least two, and / or the number of green light-emitting units 130G is at least two, and / or the number of blue light-emitting units 130B is at least two.

[0072] The at least one light-emitting unit 130 includes a light-emitting layer 131, which includes a first host material H1, a second host material H2, and a first light-emitting material D1. For example, the first host material H1 and the second host material H2 are configured to transfer fluorescence resonance energy to the first light-emitting material D1, which is configured to emit photons to achieve the purpose of emitting light. Furthermore, the first light-emitting material D1 can also reduce the quenching of excitons in the triplet energy level of the first host material H1 and / or the second host material H2, to a certain extent reducing the variability in the number of excitons at different grayscale levels, thereby reducing the efficiency decay ΔE.

[0073] The photons emitted by the first luminescent material D1 include: photons emitted by energy obtained through fluorescence resonance energy transfer from the first host material H1 and / or the second host material H2, and photons emitted by excitons formed by the recombination of electrons and holes. Specifically, the energy of the photons emitted by the first luminescent material D1 can be any of the following four energy levels:

[0074] First energy: Energy from fluorescence resonance energy transfer between the first host material H1 and the second host material H2; that is, energy transferred between the first host material H1, the second host material H2, and the first luminescent material D1. For example, the order of transfer of the first energy can be first host material H1, second host material H2, and first luminescent material D1, or alternatively, the order of transfer of the first energy can be second host material H2, first host material H1, and first luminescent material D1, without limitation.

[0075] The second energy is the energy of fluorescence resonance energy transfer from the first host material H1 ; that is, the fluorescence resonance energy transferred from the first host material H1 to the first light-emitting material D1 .

[0076] The third type of energy: energy derived from the fluorescence resonance energy transfer of the second host material H2 ; that is, the fluorescence resonance energy transferred from the second host material H2 to the first light-emitting material D1 .

[0077] The fourth energy is the energy of excitons formed by the recombination of electrons and holes in the first light-emitting material D1; that is, the energy of excitons formed by the recombination of electrons and holes in the first light-emitting material D1 itself.

[0078] It should be noted that in the following description of the present disclosure, the photons emitted by the energy obtained through fluorescence resonance energy transfer of the first host material H1 and / or the second host material H2, that is, the photons emitted through the first energy, the second energy or the third energy, are referred to as photons emitted by the first channel; the photons emitted by the excitons formed by the composite electrons and holes, that is, the photons emitted through the fourth energy, are referred to as photons emitted by the second channel.

[0079] In some embodiments, the first host material H1 and the second host material H2 in the light-emitting layer 131 undergo radiative transitions to emit photons. Therefore, the photons emitted by the light-emitting layer 131 include at least: photons emitted by the first host material H1, photons emitted by the second host material H2, and photons emitted by the first light-emitting material D1.

[0080] The ratio of the number of photons emitted by the first luminescent material D1 to the number of photons emitted by the luminescent layer 131 is greater than 80%. In other words, the ratio of the number of photons emitted by materials other than the first luminescent material D1 in the luminescent layer 131 to the number of photons emitted by the luminescent layer 131 is less than 20%. It should be noted that the photons emitted by the first luminescent material D1 include at least photons emitted by the first channel and photons emitted by the second channel. The material other than the first luminescent material D1 can be the second host material H2, or the first host material H1, or another material, without limitation.

[0081] It is understandable that, on the one hand, the wavelength of light emitted by materials such as the second host material H2 and the first host material H1 is inconsistent with the wavelength of the target light emitted by the light-emitting device 100, and therefore cannot meet the luminescence requirements of the light-emitting device 100. On the other hand, the luminescence of materials such as the second host material H2 and the first host material H1 includes both singlet and triplet energy levels. The luminescence process of the triplet energy level is relatively slow and prone to quenching, which affects the overall luminescence efficiency of the light-emitting device 100. In addition, the relatively slow luminescence process of the triplet energy level can also lead to large differences in the number of excitons under different current conditions, manifested as a large efficiency decay ΔE, resulting in display differences at different grayscales. In the embodiment of the present disclosure, the ratio of the number of photons emitted by the first light-emitting material D1 to the number of photons emitted by the light-emitting layer 131 is set to be greater than 80%, so that the number of photons emitted by the first light-emitting material D1 is relatively large, and the number of photons emitted by the second main material H2, the first main material H1 and other materials is relatively small. This can make the overall light-emitting process of the light-emitting layer 131 faster and reduce the efficiency attenuation ΔE. At the same time, the wavelength of the emitted light meets the light-emitting requirements of the light-emitting device 100, and the overall light-emitting efficiency of the light-emitting device 100 is improved.

[0082] In some embodiments, through the above configuration, the efficiency decay ΔE can be less than 6%. In other embodiments, the efficiency decay ΔE can be less than 5%.

[0083] It should be noted that the efficiency decay ΔE of the light-emitting unit 130 refers to the ratio of the absolute value of the difference between the current efficiency E1 at low current density and the current efficiency E2 at high current density to the maximum current efficiency Max(E1, E2), that is:

[0084] The maximum current efficiency Max(E1, E2) refers to the current efficiency E1 at low current density and the current efficiency E2 at high current density, whichever is greater.

[0085] Specifically, the efficiency decay ΔER of the red light emitting unit 130R, the efficiency decay ΔEG of the green light emitting unit 130G, and the efficiency decay ΔEB of the blue light emitting unit 130B are respectively:

[0086] Among them, ER1, EG1, and EB1 are the current efficiencies of the red light-emitting unit 130R, the green light-emitting unit 130G, and the blue light-emitting unit 130B at low current density, respectively; ER2, EG2, and EB2 are the current efficiencies of the red light-emitting unit 130R, the green light-emitting unit 130G, and the blue light-emitting unit 130B at high current density, respectively; Max(ER1, ER2) refers to the larger of the current efficiency ER1 of the red light-emitting unit 130R at low current density and the current efficiency ER2 of the red light-emitting unit 130R at high current density; Max(EG1, EG2) refers to the larger of the current efficiency EG1 of the green light-emitting unit 130G at low current density and the current efficiency EG2 of the green light-emitting unit 130G at high current density; Max(EB1, EB2) refers to the larger of the current efficiency EB1 of the blue light-emitting unit 130B at low current density and the current efficiency EB2 of the blue light-emitting unit 130B at high current density.

[0087] For example, low current density refers to a current density of 1 mA / cm 2 ; High current density refers to a current density of 15mA / cm 2 .

[0088] The ratio of the number of photons emitted by the first luminescent material D1 via energy obtained through fluorescence resonance energy transfer from the first host material H1 and / or the second host material H2 to the number of photons emitted by the first luminescent material D1 is greater than 60%. That is, the ratio of the number of photons emitted through the first channel to the number of photons emitted by the first luminescent material D1 is greater than 60%, while the ratio of the number of photons emitted through the second channel to the number of photons emitted by the first luminescent material D1 is less than 40%. It is understood that when the first luminescent material D1 emits photons through the first channel, energy is transferred through the first host material H1 and / or the second host material H2, generating a large number of excitons. The ratio of the number of photons emitted through the first channel to the number of photons emitted by the first luminescent material D1 being greater than 60% results in a relatively large number of photons emitted through the first channel and a relatively small number of photons emitted through the second channel, thereby improving the energy utilization of the light-emitting unit 130 and, consequently, the luminous efficiency of the light-emitting device 100.

[0089] For example, the number of photons emitted through the first channel, the number of photons emitted through the second channel, and the number of photons emitted by the first luminescent material D1 can be calculated by fitting a transient decay curve. The transient decay curve can be measured using a transient spectrometer. During measurement, a square wave signal not less than the driving voltage is input into the light-emitting device 100. The transient spectrometer is, for example, a transient fluorescence spectrometer model FLS1000; the driving voltage is, for example, 3V.

[0090] For example, the first host material H1 and the second host material H2 are two materials with relatively high doping ratios in the light-emitting layer 131, and the first host material H1 and the second host material H2 have different electron and hole transport properties. In other words, one of the first host material H1 and the second host material H2 is a hole-biased material, and the other is an electron-biased material.

[0091] In some embodiments, the mass percentage of the first luminescent material D1 in the luminescent layer 131 is less than or equal to 5% and greater than or equal to 0.5%. For example, the mass percentage of the first luminescent material D1 in the luminescent layer 131 is 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0%, or 5.0%, etc., which is not limited here.

[0092] When the mass proportion of the first luminescent material D1 in the luminescent layer 131 is less than 0.5%, on the one hand, the amount of first luminescent material D1 available to receive energy during the fluorescence resonance energy transfer process of the first host material H1 and / or the second host material H2, i.e., during the process of emitting photons through the first channel, is too small, resulting in limited luminous efficiency of the first luminescent material D1, and failing to meet the requirement that the ratio of the number of photons emitted by the first luminescent material D1 to the number of photons emitted by the luminescent layer 131 be greater than 80%. On the other hand, the number of photons emitted by the first host material H1 and / or the second host material H2 increases, and the photons emitted by the first host material H1 and / or the second host material H2 are prone to quenching, resulting in a decrease in the overall luminous efficiency of the light-emitting device 100. When the mass proportion of the first luminescent material D1 in the luminescent layer 131 is greater than 5%, the number of photons emitted through the second channel increases, and during the process of emitting photons through the second channel, excitons are prone to quenching, resulting in exciton loss and a decrease in luminous efficiency.

[0093] In some embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level HOMO(D1) of the first light-emitting material D1 and the larger of the highest occupied molecular orbital energy level HOMO(H1) of the first host material H1 and the highest occupied molecular orbital energy level HOMO(H2) of the second host material H2, Max(HOMO(H1), HOMO(H2)), is less than or equal to 0.25 eV; that is, |HOMO(D1)-Max(HOMO(H1), HOMO(H2))|≤0.25 eV.

[0094] When |HOMO(D1)-Max(HOMO(H1), HOMO(H2))| is large, for example, greater than 0.25 eV, exciton loss may occur during fluorescence resonance energy transfer of the first host material H1 and / or the second host material H2, thereby reducing the luminous efficiency of the light-emitting unit 130. By setting |HOMO(D1)-Max(HOMO(H1), HOMO(H2))| to be less than or equal to 0.25 eV, the luminous efficiency of the light-emitting unit 130 can be improved.

[0095] In some embodiments, the singlet energy level S1(H1) of the first host material H1 is greater than the singlet energy level S1(D1) of the first light-emitting material D1; the singlet energy level S1(H2) of the second host material H2 is greater than the singlet energy level S1(D1) of the first light-emitting material D1; the triplet energy level T1(H1) of the first host material H1 is greater than the triplet energy level T1(D1) of the first light-emitting material D1; the triplet energy level T1(H2) of the second host material H2 is greater than the triplet energy level T1(D1) of the first light-emitting material D1; that is, S1(H1)>S1(D1); S1(H2)>S1(D1); T1(H1)>T1(D1); T1(H2)>T1(D1).

[0096] It can be understood that when S1(H1)>S1(D1) and S1(H2)>S1(D1), at the singlet energy level, the first host material H1 can transfer energy to the first luminescent material D1, and the second host material H2 can transfer energy to the first luminescent material D1, thereby achieving efficient energy transfer from the first host material H1 and / or the second host material H2 to the first luminescent material D1 at the singlet energy level. When T1(H1)>T1(D1) and T1(H2)>T1(D1), at the triplet energy level, the first host material H1 can transfer energy to the first luminescent material D1, and the second host material H2 can transfer energy to the first luminescent material D1, thereby achieving efficient energy transfer from the first host material H1 and / or the second host material H2 to the first luminescent material D1 at the triplet energy level.

[0097] Exemplarily, the singlet energy level S1(H1) of the first host material H1 is greater than the singlet energy level S1(H2) of the second host material H2; the singlet energy level S1(H2) of the second host material H2 is greater than the singlet energy level S1(D1) of the first light-emitting material D1; the triplet energy level T1(H1) of the first host material H1 is greater than the triplet energy level T1(H2) of the second host material H2; the triplet energy level T1(H2) of the second host material H2 is greater than the triplet energy level T1(D1) of the first light-emitting material D1, that is, S1(H1)>S1(H2)>S1(D1); T1(H1)T1(H2)>T1(D1). In this way, at the singlet energy level, the energy transfer order is the first host material H1, the second host material H2, and the first light-emitting material D1; at the triplet energy level, the energy transfer order is the first host material H1, the second host material H2, and the first light-emitting material D1; the energy transfer efficiency is improved, and the luminous efficiency of the light-emitting unit 130 is improved.

[0098] In some embodiments, the lowest occupied molecular orbital energy level LOMO(D1) of the first light-emitting material D1 is greater than the smaller of the lowest occupied molecular orbital energy level LOMO(H1) of the first host material H1 and the lowest occupied molecular orbital energy level LOMO(H2) of the second host material H2, Min(LOMO(H1), LOMO(H2)); that is, LOMO(D1)>Min(LOMO(H1), LOMO(H2)).

[0099] It can be understood that when the lowest occupied molecular orbital energy level LOMO(D1) of the first light-emitting material D1 is greater than the smaller of the lowest occupied molecular orbital energy level LOMO(H1) of the first host material H1 and the lowest occupied molecular orbital energy level LOMO(H2) of the second host material H2, Min(LOMO(H1), LOMO(H2)), the capture of electrons by the first light-emitting material D1 is reduced, thereby avoiding the destruction of the balance between electrons and holes caused by the capture of electrons by the first light-emitting material D1.

[0100] In some embodiments, the hole mobility of the first host material H1 is greater than the electron mobility of the first host material H1; the electron mobility of the second host material H2 is greater than the hole mobility of the second host material H2; and the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 is greater than or equal to 0.1.

[0101] It is understood that when the hole mobility of the first host material H1 is greater than the electron mobility of the first host material H1, the first host material H1 is a hole-biased material; when the electron mobility of the second host material H2 is greater than the hole mobility of the second host material H2, the second host material H2 is an electron-biased material; by setting the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 to be greater than or equal to 0.1, the number of electrons and the number of holes are balanced, and the number of electrons and the number of holes are closer to 1:1, which is conducive to the recombination and formation of excitons on the second host material H2. For example, the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 can be 0.1, 0.2, 0.5, 1, 2, 3, or 5, etc., which is not limited here.

[0102] It should be noted that the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 is greater than or equal to 0.1, including the following two cases.

[0103] The first case: the hole mobility of the first host material H1 is greater than or equal to the electron mobility of the second host material H2; that is, the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 is greater than or equal to 1.

[0104] The second case: the hole mobility of the first host material H1 is less than the electron mobility of the second host material H2; and the ratio of the hole mobility of the first host material H1 to the electron mobility of the second host material H2 is greater than or equal to 0.1 and less than 1.

[0105] In other embodiments, the electron mobility of the first host material H1 is greater than the hole mobility of the first host material H1; the hole mobility of the second host material H2 is greater than the electron mobility of the second host material H2; and the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 is greater than or equal to 0.1.

[0106] It is understood that when the electron mobility of the first host material H1 is greater than the hole mobility of the first host material H1, the first host material H1 is an electron-biased material; when the hole mobility of the second host material H2 is greater than the electron mobility of the second host material H2, the second host material H2 is a hole-biased material; by setting the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 to be greater than or equal to 0.1, the number of electrons and the number of holes are balanced, and the number of electrons and the number of holes are closer to 1:1, which is conducive to the recombination and formation of excitons on the first host material H1. For example, the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 can be 0.1, 0.3, 0.5, 1, 2, 3, or 6, etc., which is not limited here.

[0107] It should be noted that the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 is greater than or equal to 0.1, including the following two cases.

[0108] The first case: the hole mobility of the second host material H2 is greater than or equal to the electron mobility of the first host material H1; that is, the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 is greater than or equal to 1.

[0109] The second case: the hole mobility of the second host material H2 is less than the electron mobility of the first host material H1; and the ratio of the hole mobility of the second host material H2 to the electron mobility of the first host material H1 is greater than or equal to 0.1 and less than 1.

[0110] In some embodiments, at least one of the internal quantum efficiency of the first host material H1 and the internal quantum efficiency of the second host material H2 is greater than or equal to 30%.

[0111] In related technologies, internal quantum efficiency (IQE) is a conventional indicator reflecting the luminescence performance of a material. Specifically, it refers to the percentage of photons radiated by exciton recombination within the device as a percentage of the number of carriers injected into the device. The higher the internal quantum efficiency of a material, the more excitons it produces. When the internal quantum efficiency of a material is greater than or equal to 30%, the material can be a delayed fluorescent material or a phosphorescent material, but not a fluorescent material.

[0112] At least one of the internal quantum efficiency of the first host material H1 and the internal quantum efficiency of the second host material H2 is greater than or equal to 30%, so that at least one of the first host material H1 and the second host material H2 is a delayed fluorescent material or a phosphorescent material. That is, at least one of the first host material H1 and the second host material H2 has a higher exciton yield and can utilize the energy of singlet excitons and triplet excitons to emit light, thereby improving the luminous efficiency of the light-emitting unit 130.

[0113] In some embodiments, the ratio of the mass fraction of the first host material H1 in the light-emitting layer 131 to the mass fraction of the second host material H2 in the light-emitting layer 131 is greater than or equal to 0.25 and less than or equal to 4.

[0114] It can be understood that, among the first main material H1 and the second main material H2, one is a hole-biased material and the other is an electron-biased material. The ratio of the mass proportion of the above-mentioned first main material H1 in the light-emitting layer 131 to the mass proportion of the second main material H2 in the light-emitting layer 131 is greater than or equal to 0.25 and less than or equal to 4, so that the number of electrons and the number of holes are balanced, which is conducive to the recombination and formation of excitons on the electron-biased materials in the first main material H1 and the second main material H2.

[0115] For example, the ratio of the mass fraction of the first host material H1 in the light-emitting layer 131 to the mass fraction of the second host material H2 in the light-emitting layer 131 can be 0.25, 0.5, 0.8, 1, 1.5, 2, 3 or 4, etc., which is not limited here.

[0116] In some embodiments, the absolute value of the difference between the highest occupied molecular orbital energy level HOMO(H1) of the first host material H1 and the highest occupied molecular orbital energy level HOMO(H2) of the second host material H2 is less than or equal to 0.25 eV; that is, |HOMO(H1)-HOMO(H2)|≤0.25 eV.

[0117] When the absolute value of the difference between the highest occupied molecular orbital energy level HOMO (H1) of the first host material H1 and the highest occupied molecular orbital energy level HOMO (H2) of the second host material H2 is large, a complex is easily formed between the first host material H1 and the second host material H2. This complex also generates new singlet energy levels and new triplet energy levels, causing the energy transfer direction during the light-emitting process of the light-emitting unit 130 to be inconsistent with the set energy transfer direction, thereby affecting the luminous efficiency of the light-emitting unit 130. In the embodiments of the present disclosure, by setting the absolute value of the difference between the highest occupied molecular orbital energy level HOMO (H1) of the first host material H1 and the highest occupied molecular orbital energy level HOMO (H2) of the second host material H2 to be less than or equal to 0.25 eV, energy is transferred in the set direction during the light-emitting process of the light-emitting unit 130.

[0118] In some embodiments, the structural formula of the first host material H1 can be any one of H1-1 to H1-30 shown below.

[0119] It should be noted that the above-listed structural formulas are examples of the structure of the first host material H1 and are not intended to limit the structure of the first host material H1. H1-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0120] In some embodiments, the second host material H2 includes any one of the ligand groups VIA shown in Formula VI.

[0121] wherein K is selected from a five-membered or six-membered carbocyclic ring or a carbon heterocyclic ring; and m is selected from any one of 0, 1, 2, 3 and 4.

[0122] Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen.

[0123] The ligand group VIA is connected to M, and M is selected from any one of ruthenium, osmium, iridium, palladium, copper, silver and gold; the second main material H2 includes an n-dentate ligand material formed by M as shown in the general formula VI, and the value of n is selected from any one of 3, 4, 5 and 6.

[0124] Rk, Rm and Ri are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

[0125] Furthermore, at least one of Rk, Rm, and Ri contains deuterium. Since deuterium is heavy hydrogen, setting a deuterium substitution on a carbon atom or a nitrogen atom can increase the stability of the chemical bond, thereby improving the thermal stability of the second host material H2. It should be noted that at least one of Rk, Rm, and Ri contains deuterium, which means that at least one of Rk, Rm, and Ri is deuterium, or at least one of Rk, Rm, and Ri is any one of an alkyl group, cycloalkyl group, heteroalkyl group, heterocycloalkyl group, aralkyl group, alkoxy group, aryloxy group, amino group, silanyl group, germanyl group, borane group, selenyl group, alkenyl group, cycloalkenyl group, heteroalkenyl group, alkynyl group, aryl group, heteroaryl group, acyl group, carboxylic acid group, ether, ester, nitrile, isonitrile, sulfenyl group, sulfinyl group, sulfonyl group, and phosphine group containing deuterium.

[0126] It should be noted that the value of m is selected from any one of 0, 1, 2, 3 and 4. That is, when m=0, the K ring does not exist, and the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen does not form a condensed ring; when m=1, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with one K, and K is selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=2, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with two K, and the two Ks are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=3, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with three Ks, and the three Ks are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle; when m=4, the five-membered carbon heterocycle formed by carbon No. 1, 2 and 3 and nitrogen forms a condensed ring with four Ks, and the four Ks are the same or different and independently selected from a five-membered or six-membered carbon ring or carbon heterocycle.

[0127] It can be understood that the second main material H2 includes an n-dentate ligand material formed by M as shown in the general formula VI, and the value of n is selected from any one of 3, 4, 5 and 6, that is, the ligand group VIA occupies the 1st tooth position and the 2nd tooth position of the n-dentate ligand material, and the 3rd tooth position, ..., and the nth tooth position of the n-dentate ligand material are occupied by other ligand groups. The present disclosure does not limit the structure of the ligand groups occupying the 3rd tooth position, ..., and the nth tooth position of the n-dentate ligand material.

[0128] It should be noted that the position of Rm shown in Formula VI means that Rm can be connected to any of carbon number 6, Z1, Z2, and Z3, that is, Rm can be connected to any element with a substitution position on the six-membered ring formed by carbon numbers 4, 5, and 6 and Z1, Z2, and Z3. The description of R can refer to the description of Rm above and is not repeated here.

[0129] The ligand group VIA of the second host material H2 contains a carbene group (i.e., the aforementioned five-membered carbon heterocycle formed by carbon atoms 1, 2, and 3 and nitrogen). This group can emit short-wavelength light, such as a dark blue color. Furthermore, the second host material H2 is compatible with related art processes for preparing the light-emitting device 100, such as evaporation, thereby reducing the manufacturing cost of the light-emitting device 100.

[0130] In some embodiments, the second host material H2 is selected from any one of the structures shown in the following general formula VII;

[0131] wherein K is selected from a five-membered or six-membered carbocyclic ring or a carbon heterocyclic ring; and m is selected from any one of 0, 1, 2, 3 and 4.

[0132] T and Q are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring.

[0133] Z1, Z2 and Z3 are the same or different and are independently selected from one of carbon and nitrogen.

[0134] M is selected from one of platinum and palladium.

[0135] L1 and L2 are the same or different and are independently selected from any one of B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf Rg).

[0136] Rk, Rm, Ri, Re, Rd, Rf and Rg are the same or different and are independently selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thiol, sulfinyl, sulfonyl and phosphino.

[0137] Furthermore, unlike L1 and L2, at least one of Rk, Rm, and Ri contains deuterium. Since deuterium is heavy hydrogen, the addition of deuterium to a carbon or nitrogen atom can increase the stability of the chemical bond, thereby improving the thermal stability of the second host material H2. It should be noted that at least one of Rk, Rm, and Ri contains deuterium, which means that at least one of Rk, Rm, and Ri is deuterium, or at least one of Rk, Rm, and Ri is any one of an alkyl group, cycloalkyl group, heteroalkyl group, heterocycloalkyl group, aralkyl group, alkoxy group, aryloxy group, amino group, silanyl group, germanyl group, borane group, selenyl group, alkenyl group, cycloalkenyl group, heteroalkenyl group, alkynyl group, aryl group, heteroaryl group, acyl group, carboxylic acid group, ether, ester, nitrile, isonitrile, sulfenyl group, sulfinyl group, sulfonyl group, and phosphine group containing deuterium.

[0138] It should be noted that L1 and L2 are independently selected from any one of B(Rf), N(Rf), P(Rf), O, S, Se, C=O, S=O, SO2, C(Rf Rg), Si(Rf Rg) and Ge(Rf Rg). Wherein, B(Rf) is substituted or unsubstituted boron; N(Rf) is substituted or unsubstituted nitrogen; P(Rf) is substituted or unsubstituted phosphorus; O is oxygen; S is sulfur; Se is selenium; C=O is a carbonyl group, S=O is a sulfinyl group; SO2 is a sulfone group; C(Rf Rg) is substituted or unsubstituted carbon; Si(Rf Rg) is substituted or unsubstituted silicon; Ge(Rf Rg) is substituted or unsubstituted germanium.

[0139] It should be noted that the description of m here can refer to the above description of m; the description of Rm, Ri, Re, Rd, and Rf can refer to the above description of Rm, which will not be repeated here.

[0140] In some embodiments, T and Q are not both five-membered carbocyclic rings or carboheterocyclic rings. This is because when T and Q are both five-membered carbocyclic rings or carboheterocyclic rings, the resulting compound has relatively poor stability. Therefore, the configuration of T and Q being not both five-membered carbocyclic rings or carboheterocyclic rings can improve the stability of the second host material H2.

[0141] For example, when M is platinum, the structural formula of the second host material H2 may be as shown below.

[0142] It should be noted that the above-listed structural formulas are examples of the structure of the second host material H2 and are not intended to limit the structure of the second host material H2. H2-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0143] In other embodiments, the second host material H2 is a delayed fluorescent material, which is selected from any one of the structures shown in the following general formulas VII and II;

[0144] Wherein, X2 and Y2 are the same or different and are independently selected from one of carbon and nitrogen.

[0145] R2, R3, R4 and R5 are the same or different and are independently selected from a substituted or unsubstituted substituent group VIIIA and a substituted or unsubstituted substituent group VIIIB, and among R2, R3, R4 and R5, there are at least two substituted or unsubstituted substituent groups VIIIA and at least one substituted or unsubstituted substituent group BIIIB.

[0146] The substituent group VIIIA is selected from any one of VIIIA-a to VIIIA-i.

[0147] Wherein, Z2 is selected from any one of carbon, nitrogen, oxygen and sulfur.

[0148] Rh is selected from any one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aralkyl, alkoxy, aryloxy, amino, silanyl, germanyl, borane, selenoalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, thio, sulfinyl, sulfonyl and phosphino.

[0149] The substituent group VIIIB is selected from any one of VIIIB-a to VIIIB-j.

[0150] Wherein, X3 is selected from one of oxygen and sulfur.

[0151] Rj is selected from any one of hydrogen, deuterium, halogen, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted haloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted haloalkoxy, substituted or unsubstituted aryl, substituted or unsubstituted haloaryl, substituted or unsubstituted silyl and substituted or unsubstituted heterocycle.

[0152] It should be noted that the two benzene rings in VIIIA-a can be connected by a single bond to form a substituted or unsubstituted VIIIA-a-1, the structural formula of which can be shown as follows.

[0153] It should be noted that the above structural formulas are examples of the structures of the substituent groups VIIIA and VIIIB, and are not intended to limit the structures of the substituent groups VIIIA and VIIIB. VIIIA-x and VIIIB-x in the above structural formulas are aliases for the respective structural formulas and are not part of the structural formulas.

[0154] The second host material H2 selected from the structure shown in the general formula VIII is compatible with the preparation process of the light-emitting device 100 in the related art, such as the evaporation process, thereby reducing the manufacturing cost of the light-emitting device 100.

[0155] For example, when X2 and Y2 are substituted or unsubstituted carbon, the structural formula of the second host material H2 may be as shown below.

[0156] It should be noted that the above-listed structural formulas are examples of the structure of the second host material H2 and are not intended to limit the structure of the second host material H2. H2-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0157] In some embodiments, the first luminescent material D1 is selected from any one of the structures shown in the following general formula I.

[0158] Wherein, X, Y and Z are the same or different and are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; the value of n is selected from any one of 1, 2, 3 and 4.

[0159] A and E are the same or different and are independently selected from any one of a five-membered or six-membered carbocyclic ring, a five-membered or six-membered carboheterocyclic ring and a condensed ring.

[0160] Ra, Rb, Rx, Ry, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0161] It should be noted that X, Y, and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S, and a single bond. C(Re) is substituted or unsubstituted carbon; N is nitrogen; B is boron; P is phosphorus; P=O is a phosphoryl group; Si(Re) is substituted or unsubstituted silicon; and S is sulfur. A single bond means that X, Y, or Z does not exist, and the elements connected to X, Y, or Z are directly connected by a covalent bond. Specifically, when X is selected from a single bond, carbon 2 and carbon 3 are directly connected by a covalent bond, and Rx does not exist; when Y is selected from a single bond, carbon 5 and carbon 6 are directly connected by a covalent bond, and Ry does not exist; when Z is selected from a single bond, carbon 1 and carbon 4 are directly connected by a covalent bond, and carbon 4 and carbon 7 are directly connected by a covalent bond.

[0162] For the convenience of description, the ring formed by carbon numbers 1, 2, 3, 4 and X, Z is abbreviated as WI; the ring formed by carbon numbers 4, 5, 6, 7 and Y, Z is abbreviated as WII; and the ring formed by carbon numbers 3, 4, 5, 6, 8, 9, 10 is abbreviated as WIII.

[0163] It should be noted that the value of n is selected from any one of 1, 2, 3 and 4. That is, when n=1, in the structure of the first luminescent material D1, the number of E is one, and the number of condensed rings formed by A, WI, WII, and WIII is one; when n=2, in the structure of the first luminescent material D1, the number of E is one, and the number of condensed rings formed by A, WI, WII, and WIII is two, and the two condensed rings are connected by the above-mentioned one E; when n=3, in the structure of the first luminescent material D1, the number of E is one or two, and the number of condensed rings formed by A, WI, WII, and WIII is three, and the three condensed rings are connected by the above-mentioned one or two E; when n=4, in the structure of the first luminescent material D1, the number of E is one, two, or three, and the number of condensed rings formed by A, WI, WII, and WIII is four, and the four condensed rings are connected by the above-mentioned one, two, or three E.

[0164] It should be noted that the position of R1 shown in general formula I means that R1 can be connected to any element with a substitution position on WIII, that is, R1 can be connected to any carbon with a substitution position among carbons 3, 4, 5, 6, 8, 9, and 10. The description of Ra and Rb can refer to the above description of R1 and will not be repeated here.

[0165] It should be noted that the aryl group in Cx refers to an aryl group having x carbon (C) atoms. The aryl group may be phenyl, heteroaryl furyl, pyranyl, thienyl, pyridyl, etc. The alkyl group in Cx refers to an alkyl group having x carbon (C) atoms. Where x is a positive integer, the same applies to the following.

[0166] The first luminescent material D1 contains luminescent groups XYZ, which can emit light ranging from blue to red. Specifically, the color of the light emitted by the first luminescent material D1 is related to the structural characteristics of the first luminescent material D1, including but not limited to the type and position of the substituents, and the value of n.

[0167] In some embodiments, the first luminescent material D1 is selected from any one of the structures shown in the following general formula II.

[0168] wherein X, Y, and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S, and a single bond; and Z is different from X and Y.

[0169] A, E, F and G are the same or different and are independently selected from any one of a five-membered or six-membered carbocycle, a five-membered or six-membered carboheterocycle and a condensed ring, and A, E, F and G are not six-membered carbocycles at the same time; when G is a six-membered carbocycle, F is not a six-membered carbocycle or does not exist.

[0170] Ra, Rb, Rc, Rd, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0171] It should be noted that, for the description of C(Re), N, B, P, P=O, Si(Re), S and single bonds herein, reference may be made to the above description of C(Re), N, B, P, P=O, Si(Re), S and single bonds; for the description of Ra, Rb, Rc, Rd, R1 herein, reference may be made to the above description of R1; for the description of the aryl group of Cx and the alkyl group of Cx herein, reference may be made to the above description of the aryl group of Cx and the alkyl group of Cx, and they will not be repeated here.

[0172] It can be understood that when n=1, Rx is fused with A, and Ry is fused with E in the structure shown in Formula I, the structure shown in Formula I can be transformed into the structure shown in Formula II.

[0173] It should be noted that the above-mentioned "Z is different from X and Y" means that Z is different from X and Z is different from Y. There is no limitation on whether X and Y are the same, that is, X and Y can be the same or different.

[0174] A, E, F, and G are not all six-membered carbon rings. This is because when A, E, F, and G are all six-membered carbon rings, the structure shown in Formula II is symmetrical, increasing the number of photons emitted by the first luminescent material D1 via the triplet energy level. However, the luminescence process of the triplet energy level is relatively slow, resulting in significant differences in the number of excitons under different current conditions, manifested as a large efficiency decay ΔE, and causing display differences at different grayscales. The embodiments of the present disclosure, by ensuring that A, E, F, and G are not all six-membered carbon rings, can reduce the variability in the number of excitons under different current conditions, thereby reducing display differences at different grayscales.

[0175] It should be noted that when G is a six-membered carbocyclic ring, F is not a six-membered carbocyclic ring or does not exist, which means that when G is a six-membered carbocyclic ring, F is selected from any one of a five-membered carbocyclic ring, a five-membered or six-membered carboheterocyclic ring and a condensed ring, or the F ring does not exist.

[0176] For example, when X and Y are nitrogen, Z is boron, A, E, and G are six-membered carbon rings, F is a six-membered carbon heterocycle, and Ra and Rc are C4 alkyl groups, the structural formula of the first luminescent material D1 can be as shown below.

[0177] For example, when X and Y are nitrogen, Z is boron, A, E, and G are six-membered carbon rings, F does not exist, and Ra and Rc are C4 alkyl groups, the structural formula of the first luminescent material D1 can be as shown below.

[0178] For example, when X and Y are nitrogen, Z is boron, A and G are six-membered carbon rings, and E is When F does not exist, Ra is a benzene ring, and Rc is a C4 alkyl group, the structural formula of the first light-emitting material D1 can be as shown below.

[0179] For example, when X and Y are nitrogen, Z is boron, A and G are six-membered carbon rings, and E is When F does not exist and Ra and Rc are C4 alkyl groups, the structural formula of the first light-emitting material D1 can be as shown below.

[0180] For example, when X and Y are nitrogen, Z is boron, A and G are six-membered carbon rings, and E is When F does not exist and Ra and Rc are C4 alkyl groups, the structural formula of the first light-emitting material D1 can be as shown below.

[0181] It should be noted that the above structural formulas are examples of the structure of the first luminescent material D1 and are not intended to limit the structure of the first luminescent material D1. D1-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0182] In some embodiments, the first luminescent material D1 is selected from any one of the structures shown in the following general formula III.

[0183] wherein X, Y, and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S, and a single bond; and X and Y are the same or different, and Z is different from X and Y.

[0184] A is selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring.

[0185] Ra, Rx, Ry, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0186] It should be noted that, for the description of C(Re), N, B, P, P=O, Si(Re), S and single bonds herein, reference may be made to the above description of C(Re), N, B, P, P=O, Si(Re), S and single bonds; for the description of Ra and R1 herein, reference may be made to the above description of R1; for the description of the aryl group of Cx and the alkyl group of Cx herein, reference may be made to the above description of the aryl group of Cx and the alkyl group of Cx, and they will not be repeated here.

[0187] It can be understood that when in the structure shown in general formula I, the number of E is one, and E is a six-membered carbon ring, Rb is hydrogen, and n=2, that is, the number of condensed rings formed by A, WI, WII, and WIII is two, and the two condensed rings are connected by the above-mentioned one E, the structure shown in general formula I can be transformed into the structure shown in general formula III.

[0188] It should be noted that the above-mentioned Z is different from X and Y, which means that Z is different from X, and Z is different from Y.

[0189] For example, when X is a single bond, Y is boron, Z is nitrogen, A is a six-membered carbon ring, and Rx does not exist, the structural formula of the first light-emitting material D1 may be as shown below.

[0190] For example, when X is oxygen, Y is boron, Z is nitrogen, A is a six-membered carbon ring, Rx does not exist, R1 and Ra are hydrogen, and Ry is a substituted C6 aromatic group, the structural formula of the first light-emitting material D1 can be as shown below.

[0191] For example, when X is substituted silicon, Y is boron, Z is nitrogen, A is a six-membered carbon ring, Rx is a benzene ring, R1 and Ra are hydrogen, and Ry is a substituted C6 aromatic group, the structural formula of the first light-emitting material D1 can be as shown below.

[0192] It should be noted that the above structural formulas are examples of the structure of the first luminescent material D1 and are not intended to limit the structure of the first luminescent material D1. D1-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0193] In some embodiments, the first luminescent material D1 is selected from any one of the structures shown in the following general formula IV.

[0194] wherein X, Y, Z and X1 are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond, and when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different.

[0195] A and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A and E are not six-membered carbocyclic rings at the same time.

[0196] Ra, Rb, Rx, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0197] It should be noted that, for the description of C(Re), N, B, P, P=O, Si(Re), S and a single bond herein, reference may be made to the above description of C(Re), N, B, P, P=O, Si(Re), S and a single bond; for the description of Ra, Rb, and R1 herein, reference may be made to the above description of R1; for the description of the aryl group of Cx and the alkyl group of Cx herein, reference may be made to the above description of the aryl group of Cx and the alkyl group of Cx, and they will not be repeated here.

[0198] It is understood that when, in the structure of Formula I, there is one E, there are multiple R1s, and one of the R1s is fused with Ry, the structure of Formula I can be transformed into the structure of Formula IV. By selecting the first luminescent material D1 from any of the structures of Formula IV, the number of fused sites in the first luminescent material D1 increases, thereby enhancing the resonance effect.

[0199] It should be noted that in the structure of Formula IV, Z and Y are not both boron. This is because when both Z and Y are boron, the formation of the resonant structure is affected, thereby affecting the luminescence performance of the first luminescent material D1. In the embodiments of the present disclosure, by arranging Z and Y not both boron, the first luminescent material D1 can reliably perform its luminescence function.

[0200] In some embodiments, the first light-emitting material D1 is selected from any one of the structures shown in the following general formula V.

[0201] wherein X, Y, Z, X1 and Y1 are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and, when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different; and Y1 and X are different.

[0202] A, E and J are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A, E and J are not six-membered carbocyclic rings at the same time.

[0203] Ra, Rb, Rc, Rx, R1 and Re are the same or different and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

[0204] It should be noted that, for the description of C(Re), N, B, P, P=O, Si(Re), S and single bonds herein, reference may be made to the above description of C(Re), N, B, P, P=O, Si(Re), S and single bonds; for the description of Ra, Rb, Rc, R1 herein, reference may be made to the above description of R1; for the description of the aryl group of Cx and the alkyl group of Cx herein, reference may be made to the above description of the aryl group of Cx and the alkyl group of Cx, and they will not be repeated here.

[0205] It is understood that when Ra adjacent to X and Z in the structure of Formula IV is fused with Rx, the structure of Formula IV can be transformed into the structure of Formula V. By selecting the first luminescent material D1 from any of the structures of Formula V, multiple fused sites are formed in the structure of the first luminescent material D1, effectively increasing the resonance effect.

[0206] For example, when X is nitrogen, Y is nitrogen, Z is boron, X1 is boron, Y1 is substituted boron, A, E, and J are six-membered carbon rings, Rb is hydrogen, R1, Ra, and Rc are C4 alkyl groups, and Rx is a substituted C6 aromatic group, the structural formula of the first light-emitting material D1 can be as shown below.

[0207] For example, when X is nitrogen, Y is boron, Z is boron, X1 is nitrogen, Y1 is substituted carbon, A, E, and J are six-membered carbon rings, Rb is hydrogen, R1, Ra, and Rc are C4 alkyl groups, and Rx is a substituted C6 aromatic group, the structural formula of the first light-emitting material D1 can be as shown below.

[0208] For example, when X is nitrogen, Y is boron, Z is boron, X1 is nitrogen, Y1 is substituted carbon, A, E, and J are six-membered carbon rings, Rb is hydrogen, R1, Ra, and Rc are C4 alkyl groups, Rx is a substituted C6 aromatic group, and Rx is connected to A by a covalent bond, the structural formula of the first light-emitting material D1 can be as shown below.

[0209] For example, when X is nitrogen, Y is boron, Z is boron, X1 is nitrogen, Y1 is substituted silicon, A, E, and J are six-membered carbon rings, Rb is hydrogen, R1, Ra, and Rc are C4 alkyl groups, and Rx is a substituted C6 aromatic group, the structural formula of the first light-emitting material D1 can be as shown below.

[0210] It should be noted that the above structural formulas are examples of the structure of the first luminescent material D1 and are not intended to limit the structure of the first luminescent material D1. D1-x in the above structural formulas is a generic name for each structural formula and is not part of the structural formula. Where x is a positive integer, the same applies to the following.

[0211] In some embodiments, the molecular weight of the first luminescent material D1 is less than or equal to 1250.

[0212] For example, the molecular weight of the first luminescent material D1 is less than 1250, or the molecular weight of the first luminescent material D1 is equal to 1250. For example, the molecular weight of the first luminescent material D1 can be 300, 400, 550, 800, 1000 or 1250, etc., which is not limited here.

[0213] It is understood that when the molecular weight of the first luminescent material D1 is greater than 1250, the compatibility of the first luminescent material D1 with the related art manufacturing process of the light-emitting device 100 is relatively poor, such as the evaporation process. In the embodiments of the present disclosure, by setting the molecular weight of the first luminescent material D1 to be less than or equal to 1250, the first luminescent material D1 is compatible with the related art manufacturing process of the light-emitting device 100, such as the evaporation process, thereby reducing the manufacturing cost of the light-emitting device 100.

[0214] In some embodiments, at least one light-emitting layer 131 further includes a second light-emitting material D2; the singlet energy level S1(D2) of the second light-emitting material D2 is less than the singlet energy level S1(D1) of the first light-emitting material D1; the triplet energy level T1(D2) of the second light-emitting material D2 is greater than the triplet energy level T1(D1) of the first light-emitting material D1, that is, S1(D2)<S1(D1), and T1(D2)>T1(D1).

[0215] It can be understood that when S1(D2)<S1(D1), on the one hand, the second light-emitting material D2 can quench the excess excitons in the light-emitting layer 131, thereby improving the device life of the light-emitting device 100; on the other hand, at the singlet energy level, the addition of the second light-emitting material D2 will not affect the first light-emitting material D1 receiving the energy transmitted from the first main material H1 and / or the second main material H2, so that the first light-emitting material D1 can receive the energy transmitted by the first main material H1 and / or the second main material H2, and play the function of emitting light. When T1(D2)>T1(D1), at the triplet energy level, the second light-emitting material D2 can transfer energy to the first light-emitting material D1, realizing effective energy transfer from the second light-emitting material D2 to the first light-emitting material D1 at the triplet energy level. In this way, at the triplet energy level, the first host material H1 and / or the second host material H2 can first transfer energy to the second light-emitting material D2, and then the second light-emitting material D2 transfers energy to the first light-emitting material D1, thereby alleviating the problem that the energy transfer process of the first host material H1 and / or the second host material H2 at the triplet energy level is relatively slow and prone to quenching, thereby improving the overall luminous efficiency of the light-emitting device 100.

[0216] Illustratively, the singlet energy level S1(D2) of the second luminescent material D2 is smaller than the singlet energy level S1(D1) of the first luminescent material D1, and the singlet energy level S1(D1) of the first luminescent material D1 is smaller than the singlet energy level S1(H2) of the second host material H2; the triplet energy level T1(H2) of the second host material H2 is greater than the triplet energy level T1(D2) of the second luminescent material D2, and the triplet energy level T1(D2) of the second luminescent material D2 is greater than the triplet energy level T1(D1) of the first luminescent material D1, that is, S1(D2)<S1(D1)<S1(H2), and T1(H2)>T1(D2)>T1(D1).

[0217] It can be understood that when S1(D2)<S1(D1)<S1(H2), at the singlet energy level, the order of energy transfer is the second main material H2, the first light-emitting material D1, and the second light-emitting material D2, thereby achieving effective energy transfer from the second main material H2 to the first light-emitting material D1 at the singlet energy level, so that the addition of the second light-emitting material D2 will not affect the first light-emitting material D1 receiving the energy transmitted from the second main material H2, thereby improving the luminous efficiency of the light-emitting device 100. When T1(H2)>T1(D2)>T1(D1), at the triplet energy level, the order of energy transfer is the second host material H2, the second light-emitting material D2, and the first light-emitting material D1. In this way, at the triplet energy level, the second host material H2 can first transfer energy to the second light-emitting material D2, and then the second light-emitting material D2 transfers energy to the first light-emitting material D1, thereby alleviating the problem that the energy transfer process of the second host material H2 at the triplet energy level is relatively slow and prone to quenching, thereby improving the overall luminous efficiency of the light-emitting device 100.

[0218] In some embodiments, the second luminescent material D2 is a phosphorescent material or a delayed fluorescent material. In other embodiments, the second luminescent material D2 can be selected from some of the structures shown in the above general formula I, as long as the singlet energy level S1(D2) of the second luminescent material D2 is less than the singlet energy level S1(D1) of the first luminescent material D1, and the triplet energy level T1(D2) of the second luminescent material D2 is greater than the triplet energy level T1(D1) of the first luminescent material D1. These requirements are not limited here.

[0219] In some embodiments, the mass fraction of the second luminescent material D2 in the luminescent layer 131 is less than or equal to 5% and greater than or equal to 0.1%. For example, the mass fraction of the second luminescent material D2 in the luminescent layer 131 can be 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, or 5.0%, etc., without limitation. When the mass fraction of the second luminescent material D2 in the luminescent layer 131 is less than 0.1%, the second luminescent material D2 may not be able to improve the overall luminous efficiency of the light-emitting device 100. When the mass fraction of the second luminescent material D2 in the luminescent layer 131 is greater than 5%, on the one hand, the second luminescent material D2 emits relatively more light, which cannot meet the luminescence requirements of the light-emitting device 100; on the other hand, the second luminescent material D2 emits more light at the triplet energy level. The luminescence process of the triplet energy level is relatively slow and prone to quenching, which affects the overall luminous efficiency of the light-emitting device 100.

[0220] In order to objectively evaluate the technical effects of the embodiments of the present disclosure, the technical solutions provided by the present disclosure will be described in detail and exemplarily through the following experimental examples and comparative examples.

[0221] The following examples and comparative examples use different materials to form the light-emitting layer 131 of the light-emitting device 100, and compare the voltage, luminous efficiency, device life, color of emitted light, and efficiency decay ΔE of the light-emitting unit 130 of the light-emitting device 100. The color of the emitted light is represented by the chromaticity coordinates CIEx and CIEy in the CIE chromaticity diagram.

[0222] In the related art, the CIE chromaticity diagram is a color system created by the International Commission on Illumination (CIE), in which color attributes can be represented by chromaticity coordinates CIEx and CIEy.

[0223] In the following comparative examples and embodiments, the structure of the light emitting device 100 and the test conditions of the light emitting device 100 are the same.

[0224] For example, referring to FIG4 , the method for preparing the light-emitting device 100 is as follows: using the material of the first electrode 110 (indium tin oxide), the material of the hole injection layer 140, the material of the hole transport layer 150, the material of the electron blocking layer 160, the material of the light-emitting layer 131, the material of the hole blocking layer 190, the material of the electron transport layer 180, the material of the electron injection layer 170, and the material of the second electrode 120, the first electrode 110, the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the light-emitting layer 131, the hole blocking layer 190, the electron transport layer 180, the electron injection layer 170, and the second electrode 120 are sequentially formed on the backplane. The process for forming the first electrode 110, the hole injection layer 140, the hole transport layer 150, the electron blocking layer 160, the light-emitting functional layer 212, the hole blocking layer 190, the electron transport layer 180, the electron injection layer 170, and the second electrode 120 is, for example, an evaporation process.

[0225] It should be noted that the light-emitting devices 100 in the comparative example and the embodiment are light-emitting devices 100 having a single-layer light-emitting layer 131, that is, each light-emitting unit 130 includes a light-emitting layer 131. The thickness and materials of the first electrode 110, hole injection layer 140, hole transport layer 150, electron blocking layer 160, hole blocking layer 190, electron transport layer 180, electron injection layer 170, and second electrode 120 in the embodiment and the comparative example are the same, and the thickness of the light-emitting layer 131 is the same, 30 nm; however, the materials of the light-emitting layer 131 are different.

[0226] The light-emitting layer 131 in the following comparative examples includes a comparative light-emitting material. The comparative light-emitting materials involved in the following comparative examples include:

[0227] It should be noted that RC-1 and RC-2 in the above structural formulas are aliases for each structural formula and are not part of the structural formula structure.

[0228] The materials of the light emitting layer 131 of the embodiment and the comparative example are described below.

[0229] In Example 1, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 69%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the first light-emitting material D1 is shown in D1-13, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 1%.

[0230] In Example 2, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 69%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the first light-emitting material D1 is shown in D1-16, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 1%.

[0231] In Example 3, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 79%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 20%; the structural formula of the first light-emitting material D1 is shown in D1-13, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 1%.

[0232] In Example 4, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 59%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 40%; the structural formula of the first light-emitting material D1 is shown in D1-13, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 1%.

[0233] In Example 5, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 69.5%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the first light-emitting material D1 is shown in D1-16, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 0.5%.

[0234] In Example 6, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a first light-emitting material D1. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 68.5%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the first light-emitting material D1 is shown in D1-16, and the mass proportion of the first light-emitting material D1 in the light-emitting layer 131 is 1.5%.

[0235] In Comparative Example 1, the light-emitting layer 131 includes a first host material H1 and a second host material H2. The structural formula of the first host material H1 is shown in H1-6, and the first host material H1 accounts for 70% by weight of the light-emitting layer 131. The structural formula of the second host material H2 is shown in H2-17, and the second host material H2 accounts for 30% by weight of the light-emitting layer 131. The light-emitting layer 131 does not contain the first light-emitting material D1.

[0236] In Comparative Example 2, the light-emitting layer 131 includes a first host material H1 and a first light-emitting material D1. The structural formula of the first host material H1 is shown in H1-6, and the first host material H1 accounts for 99% by mass of the light-emitting layer 131. The structural formula of the first light-emitting material D1 is shown in D1-13, and the first light-emitting material D1 accounts for 1% by mass of the light-emitting layer 131. The light-emitting layer 131 does not contain the second host material H2.

[0237] In Comparative Example 3, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a comparative light-emitting material. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 69%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the comparative light-emitting material is shown in RC-1, and the mass proportion of the comparative light-emitting material in the light-emitting layer 131 is 1%.

[0238] In Comparative Example 4, the light-emitting layer 131 includes a first main material H1, a second main material H2 and a comparative light-emitting material. The structural formula of the first main material H1 is shown in H1-6, and the mass proportion of the first main material H1 in the light-emitting layer 131 is 69%; the structural formula of the second main material H2 is shown in H2-17, and the mass proportion of the second main material H2 in the light-emitting layer 131 is 30%; the structural formula of the comparative light-emitting material is shown in RC-2, and the mass proportion of the comparative light-emitting material in the light-emitting layer 131 is 1%.

[0239] In order to more clearly describe the differences in the structural formulas of the first host material H1, the second host material H2, and the first light-emitting material D1 used in the embodiment and the comparative example, as well as their differences in mass proportions in the light-emitting layer 131, the following Table 1 is used to more clearly show the structural formulas of the first host material H1, the second host material H2, and the first light-emitting material D1 used in the embodiment and the comparative example, as well as their mass proportions in the light-emitting layer 131.

[0240] Table 1

[0241] It should be noted that the " / " in Table 1 indicates that the material corresponding to that sub-grid is not added to the light-emitting layer 131. For example, the sub-grid corresponding to the second host material H2 and its mass fraction in Comparative Example 2 is " / ", which means that the second host material H2 is not added to the light-emitting layer 131 of Comparative Example 2. "Ax; y%" in Table 1 refers to the corresponding structural formula Ax and the corresponding mass fraction y%. For example, the sub-grid corresponding to the first host material H1 and its mass fraction in the light-emitting layer 131 of Example 1 is "H1-6; 69%", which means that in the light-emitting layer 131 of Example 1, the structural formula of the first host material H1 is shown as H1-6, and the mass fraction of the first host material H1 in the light-emitting layer 131 is 69%. The structural formulas represented by H1-x, H2-x, D1-x, and RC-x (x is a positive integer) are as described above and are not repeated here.

[0242] The first host material H1, the second host material H2, the first light-emitting material D1, the highest occupied molecular orbital energy level (HOMO), the lowest occupied molecular orbital energy level (LOMO), the singlet energy level (S1), the triplet energy level (T1), the hole mobility, and the electron mobility of the comparative light-emitting material shown in Table 1 are shown in Table 2.

[0243] Table 2

[0244] It should be noted that the units of the highest occupied molecular orbital energy level (HOMO), the lowest occupied molecular orbital energy level (LOMO), the singlet energy level (S1), and the triplet energy level (T1) in Table 2 are electron volts, with the symbol eV; the units of hole mobility and electron mobility are square centimeters / (volt-second), with the symbol cm 2 / V·s. A "-" in Table 2 indicates that the corresponding parameter in that sub-grid is not listed in this disclosure. For example, the sub-grid corresponding to the electron mobility of the first host material H1 is "-," indicating that the electron mobility of the first host material H1 is not listed in this disclosure. The structural formulas represented by H1-x, H2-x, D1-x, and RC-x (x is a positive integer) are described above and are not repeated here.

[0245] Based on the above materials, the light-emitting devices 100 of Examples 1 to 5 and Comparative Examples 1 to 4 were tested for voltage (V), luminous efficiency (cd / A), device lifetime, emitted light color, and efficiency decay ΔE. The voltage (V), luminous efficiency (cd / A), and device lifetime data were based on Example 1. The test results are shown in Table 3 below. Device lifetime is characterized by the parameter LT95, and the emitted light color is represented by the chromaticity coordinates CIEx and CIEy in the CIE chromaticity diagram.

[0246] Table 3

[0247] Based on the above materials, the emission spectra of the light-emitting devices 100 corresponding to Example 1, Example 2, Example 5, Example 6, Comparative Example 1, and Comparative Example 2 were tested. The emission spectra of the light-emitting devices 100 corresponding to Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIG5 , and the emission spectra of the light-emitting devices 100 corresponding to Example 2, Example 5, and Example 6 are shown in FIG6 .

[0248] It should be noted that in Figures 5 and 6 , the emission spectra corresponding to Examples 1, 2, 5, 6, Comparative Example 1, and 2 all exhibit luminescence at a wavelength of 550 nm. Furthermore, the luminescence at 550 nm in the emission spectrum corresponding to Comparative Example 2 is the weakest, indicating that the luminescence intensity at 550 nm in the emission spectrum is enhanced when the second host material H2 is included in the luminescent layer 131. Therefore, the luminescence intensity at 550 nm can represent the intrinsic emission of the second host material H2, i.e., the radiative transition process of the second host material H2 itself. In other words, the luminescence intensity at 550 nm can represent the relative intensity of the light emitted by the second host material itself. Furthermore, the higher the luminescence intensity at 550 nm, the stronger the intrinsic emission of the second host material H2.

[0249] Comparing Example 1 with Comparative Examples 1 and 2, as shown in Table 3, Example 1 exhibits significantly improved device efficiency, with the device efficiency ranking from highest to lowest being: Example 1, Comparative Example 1, Comparative Example 2. This is due to the fact that both the second host material H2 and the first luminescent material D1 undergo a process of self-recombined electron-hole radiative transitions to form exciton states, and the luminous efficiency of the second host material H2 itself is much higher than that of the first luminescent material D1, indicating that the second host material H2 has a good internal quantum efficiency and exciton yield.

[0250] Compared with Comparative Example 1, see Figure 5. The emission spectrum of Example 1 is significantly narrower and closer to the emission spectrum of Comparative Example 2, indicating that in Example 1, the second host material H2 transfers Forster energy to the first luminescent material D1, and the first luminescent material D1 emits light.

[0251] Compared with Comparative Example 2, please refer to Figure 5. The emission intensity of Example 1 at a wavelength of 550nm is significantly higher. This is because in the luminescence process of Example 1, there is an electron-hole recombination excitation transition of the first luminescent material D1 itself, and the second main material H2 transfers energy to the first luminescent material D1. At the same time, there is also a radiation transition process of the second main material H2 itself.

[0252] Comparing Example 1 with Example 3 and Example 4, see Table 3. The device efficiency is ranked from high to low as follows: Example 3, Example 1, Example 4; the device lifetime is ranked from long to short as follows: Example 4, Example 1, Example 3; and the efficiency decay ΔE is ranked from small to large as follows: Example 4, Example 1, Example 3. This is because as the doping ratio of the second host material H2 increases, the excited state density in the second host material H2 decreases. This decrease in excited state density in the second host material H2 leads to a decrease in device efficiency. However, this decrease in excited state density in the second host material H2 suppresses energy quenching in the second host material H2 to a certain extent, thereby increasing device lifetime and reducing the difference in the number of excitons at different grayscale levels, resulting in a decrease in efficiency decay ΔE.

[0253] Comparing Example 2 with Example 5 and Example 6, please refer to Table 3. The device efficiency is ranked from high to low as follows: Example 6, Example 2, Example 5; the efficiency decay ΔE is ranked from small to large as follows: Example 5, Example 2, Example 6; and the device lifespan is: Example 5 is higher than Example 6 and Example 2. Please continue to refer to Figure 6. As the doping ratio of the first luminescent material D1 increases, the emission intensity at a wavelength of 550nm decreases. This is because, on the one hand, as the doping ratio of the first luminescent material D1 increases, the energy transfer from the second host material H2 to the first luminescent material D1 becomes more complete, that is, the first luminescent material D1 primarily emits light, while the second host material H2 emits less light or no light, resulting in a decrease in the emission intensity at 550nm. Secondly, the energy transfer channels from the second main material H2 to the first light-emitting material D1 increase, which increases the energy transfer from the second main material H2 to the first light-emitting material D1, which is manifested as an increase in device efficiency. However, the energy transfer from the second main material H2 to the first light-emitting material D1 increases, which increases the excited state density on the first light-emitting material D1, and to a certain extent increases the energy quenching of the first light-emitting material D1, resulting in a decrease in device life. At the same time, it increases the difference in the number of excitons under different gray levels, and the efficiency attenuation ΔE increases.

[0254] Compared with Comparative Examples 3 and 4, please refer to Table 3. Example 1 shows that the device efficiency of Comparative Examples 3 and 4 is significantly reduced. This is because the highest occupied molecular orbital energy level (HOMO) of the comparative luminescent materials RC-1 and RC-2 in Comparative Examples 3 and 4 is significantly different from the highest occupied molecular orbital energy level (HOMO) of the first host material H1 and the second host material H2, and the difference is greater than 0.3 eV, which easily generates hole traps. As a result, the comparative luminescent materials RC-1 and RC-2 themselves easily obtain holes, resulting in a decrease in exciton yield and a decrease in device efficiency.

[0255] The light-emitting devices 100 in Examples 1 to 6 are selected from some embodiments of the present disclosure. From the above analysis, it can be seen that compared with Comparative Examples 1 to 4, the light-emitting devices 100 in Examples 1 to 6 all have low voltage, high efficiency, and long life device performance, and the efficiency attenuation ΔE value is small, which can reach less than or equal to 7%, which is conducive to high-quality picture display effects.

[0256] It can be seen that the present disclosure provides a light-emitting layer 131 including a first main material H1, a second main material H2 and a first light-emitting material D1, and limits the proportion of the number of photons emitted by the first light-emitting material D1 and the proportion of the number of photons emitted by the second channel, so that the light-emitting device 100 has low voltage, high efficiency and long life device performance, and the efficiency decay ΔE value is small, which alleviates the problem of color cast at different grayscales and reduces the display difference at different grayscales. At the same time, when the efficiency decay ΔE value is small, the difference in efficiency decay trend of the current of red (R), green (G) and blue (B) at different grayscales can be reduced, thereby improving the problem of greening and redding at low grayscales, and at the same time improving the problem of excessive difference in luminous efficiency at low brightness and high brightness, which is conducive to high-quality picture quality display effect and realizes normal display effect at different grayscales.

[0257] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in the present disclosure should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A light emitting device, include: A first electrode and a second electrode are stacked; at least one light emitting unit disposed between the first electrode and the second electrode; Wherein, the at least one light-emitting unit comprises a light-emitting layer, and the light-emitting layer comprises: a first host material, a second host material and a first light-emitting material; The photons emitted by the first luminescent material include: photons emitted by energy obtained through fluorescence resonance energy transfer of the first host material and / or the second host material, and photons emitted by excitons formed by recombining electrons and holes; The ratio of the number of photons emitted by the first luminescent material to the number of photons emitted by the luminescent layer is greater than 80%; and the ratio of the number of photons emitted by the first luminescent material through energy obtained by fluorescence resonance energy transfer of the first host material and / or the second host material to the number of photons emitted by the first luminescent material is greater than 60%.

2. The light emitting device according to claim 1, in, The mass proportion of the first light-emitting material in the light-emitting layer is less than or equal to 5% and greater than or equal to 0.5%.

3. The light emitting device according to claim 1 or 2, in, The absolute value of the difference between the highest occupied molecular orbital energy level of the first light-emitting material and the larger of the highest occupied molecular orbital energy level of the first host material and the highest occupied molecular orbital energy level of the second host material is less than or equal to 0.25 eV.

4. The light emitting device according to any one of claims 1 to 3, in, The singlet energy level of the first host material is greater than the singlet energy level of the first light-emitting material; The singlet energy level of the second host material is greater than the singlet energy level of the first light-emitting material; The triplet energy level of the first host material is greater than the triplet energy level of the first light-emitting material; The triplet energy level of the second host material is greater than the triplet energy level of the first light-emitting material.

5. The light emitting device according to any one of claims 1 to 4, in, The lowest occupied molecular orbital energy level of the first light-emitting material is greater than the smaller of the lowest occupied molecular orbital energy level of the first host material and the lowest occupied molecular orbital energy level of the second host material.

6. The light emitting device according to any one of claims 1 to 5, in, The hole mobility of the first host material is greater than the electron mobility of the first host material; the electron mobility of the second host material is greater than the hole mobility of the second host material; and the ratio of the hole mobility of the first host material to the electron mobility of the second host material is greater than or equal to 0.

1.

7. The light emitting device according to any one of claims 1 to 5, in, The electron mobility of the first host material is greater than the hole mobility of the first host material; the hole mobility of the second host material is greater than the electron mobility of the second host material; and the ratio of the hole mobility of the second host material to the electron mobility of the first host material is greater than or equal to 0.

1.

8. The light emitting device according to any one of claims 1 to 7, in, At least one of an internal quantum efficiency of the first host material and an internal quantum efficiency of the second host material is greater than or equal to 30%.

9. The light emitting device according to any one of claims 1 to 8, in, A ratio of a mass fraction of the first host material in the light-emitting layer to a mass fraction of the second host material in the light-emitting layer is greater than or equal to 0.25 and less than or equal to 4.

10. The light emitting device according to any one of claims 1 to 9, in, An absolute value of a difference between a highest occupied molecular orbital energy level of the first host material and a highest occupied molecular orbital energy level of the second host material is less than or equal to 0.25 eV.

11. The light emitting device according to any one of claims 1 to 10, in, The first luminescent material is selected from any one of the structures shown in the following general formula I; wherein X, Y and Z are the same or different and are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and the value of n is selected from any one of 1, 2, 3 and 4; A and E are the same or different and are independently selected from any one of a five-membered or six-membered carbocyclic ring, a five-membered or six-membered carbocyclic ring and a condensed ring; Ra, Rb, Rx, Ry, R 1 and Re are the same as or different from Re and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

12. The light emitting device according to any one of claims 1 to 11, in, The first luminescent material is selected from any one of the structures shown in the following general formula II; Wherein, X, Y and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond. species; and, Z is different from X and Y; A, E, F and G are the same or different and are independently selected from any one of a five-membered or six-membered carbocyclic ring, a five-membered or six-membered carboheterocyclic ring and a condensed ring, and A, E, F and G are not six-membered carbocyclic rings at the same time; when G is a six-membered carbocyclic ring, F is not a six-membered carbocyclic ring or does not exist; Ra, Rb, Rc, Rd, R 1 and Re are the same as or different from each other, and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl, and substituted or unsubstituted C1-C50 alkyl.

13. The light emitting device according to any one of claims 1 to 11, in, The first luminescent material is selected from any one of the structures shown in the following general formula III; wherein X, Y and Z are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and X and Y are the same or different, and Z is different from X and Y; A is selected from a five-membered or six-membered carbocyclic or carbon heterocyclic ring; Ra, Rx, Ry, R 1 and Re are the same as or different from Re and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

14. The light emitting device according to any one of claims 1 to 11, in, The first luminescent material is selected from any one of the structures shown in the following general formula IV; wherein X, Y, Z and X1 are independently selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond, and when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different; A and E are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A and E are not six-membered carbocyclic rings at the same time; Ra, Rb, Rx, R 1 and Re are the same as or different from Re and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

15. The light emitting device according to any one of claims 1 to 11, in, The first luminescent material is selected from any one of the structures shown in the following general formula V; wherein X, Y, Z, X1 and Y1 are selected from any one of C(Re), N, B, P, P=O, Si(Re), S and a single bond; and, when Z and Y are the same, X and X1 are the same; when Z and Y are different, X and X1 are different; Y1 and X are different; A, E and J are the same or different and are independently selected from a five-membered or six-membered carbocyclic ring or a carboheterocyclic ring; and A, E and J are not six-membered carbocyclic rings at the same time; Ra, Rb, Rc, Rx, R 1 and Re are the same as or different from Re and are independently selected from any one of hydrogen, deuterium, cyano, substituted or unsubstituted C5-C50 aryl and substituted or unsubstituted C1-C50 alkyl.

16. The light emitting device according to any one of claims 1 to 15, in, The molecular weight of the first luminescent material is less than or equal to 1250.

17. The light emitting device according to any one of claims 1 to 16, in, The at least one light-emitting layer further comprises a second light-emitting material; The singlet energy level of the second luminescent material is lower than the singlet energy level of the first luminescent material; The triplet energy level of the second light-emitting material is greater than the triplet energy level of the first light-emitting material.

18. The light emitting device according to claim 17, in, The mass proportion of the second light-emitting material in the light-emitting layer is less than or equal to 5% and greater than or equal to 0.1%.

19. A display panel comprising the light emitting device according to any one of claims 1 to 18; return include: A driving circuit is used to drive the light emitting device to emit light.

20. A display device comprising the display panel according to claim 19; Also includes: A driving chip is used to drive the display panel to display.

Images