A light-emitting layer, a light-emitting device, and a light-emitting apparatus

Abstract

This invention provides a light-emitting layer comprising: a TADF material, a phosphorescent material, a multi-resonance fluorescent material, and a host material. The addition of the phosphorescent material to the light-emitting layer enables it to receive triplet excitons, which can then be transferred to the singlet energy levels of the multi-resonance fluorescent material, reducing the number of triplet excitons within the device and improving its lifetime. The multi-resonance fluorescent material can convert triplet excitons into singlet excitons while receiving a small number, improving the device's efficiency. Due to the dual quenching effect of the phosphorescent material and the multi-resonance fluorescent material on the TADF material, the luminescence of the TADF material can be completely suppressed, improving the stability of the emission spectrum. This invention also provides a light-emitting device and a light-emitting apparatus.

Description

Technical Field

[0001] This invention belongs to the field of light-emitting technology, and particularly relates to a light-emitting layer, a light-emitting device, and a light-emitting apparatus. Background Technology

[0002] Multiple resonance fluorescent materials are a type of high-efficiency, narrow-spectrum luminescent material that has emerged in recent years. Due to the opposite vibrational directions of BN, HOMO and LUMO can be separated on the molecular backbone, thereby achieving narrow-band fluorescence emission while forming a small single triplet energy level difference. OLED devices that simultaneously dope the luminescent layer with narrow-spectrum fluorescent materials and TADF materials can achieve high-efficiency luminescence and pure light color; this technology is called superfluorescence technology.

[0003] In OLEDs, triplet excitons are predominant. TDAF materials can convert triplet excitons into light, and TADF-sensitized fluorescence exhibits high color purity. However, TDAF itself has a broad spectrum, making it less than ideal for light emission. Although multiple resonance fluorescent materials (narrow-spectrum fluorescent materials) are added, the problem persists: high-energy triplet excitons on TADF cannot be converted into singlet excitons in a timely manner, resulting in OLED devices remaining in a high-energy state for extended periods and leading to shorter device lifetimes. Furthermore, because triplet excitons transfer energy to the fluorescent material via the Dexter mechanism, and TADF transfers energy to the fluorescent material via the Foster mechanism, there may be two light emission mechanisms—TADF and fluorescence—leading to an unstable emission spectrum. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a light-emitting layer and its application. The light-emitting device prepared by the light-emitting layer provided by the present invention has a long lifespan, high efficiency, good transmission, and stable emission spectrum.

[0005] This invention provides a light-emitting layer, comprising:

[0006] TADF materials, phosphorescent materials, multiple resonance fluorescent materials, and host materials.

[0007] The present invention provides a light-emitting device, comprising: the light-emitting layer described in the above technical solution.

[0008] The present invention provides a light-emitting device, comprising: the light-emitting device described in the above technical solution.

[0009] This invention incorporates phosphorescent materials into the emitting layer, enabling the reception of triplet excitons. These triplet excitons can then be transferred to the singlet energy levels of the multi-resonant fluorescent material, reducing the number of triplet excitons within the device and improving its lifetime. The multi-resonant fluorescent material can convert triplet excitons into singlet excitons while receiving a small number, thus improving device efficiency. Due to the dual quenching effect of the phosphorescent and multi-resonant fluorescent materials on the TADF material, the luminescence of the TADF material can be completely suppressed, improving the stability of the emission spectrum.

[0010] In this invention, triplet excitons are converted into singlet excitons through the synergistic effect of TADF material, phosphorescent material, and multi-resonant fluorescent material, reducing the number of triplet excitons and improving device lifetime and efficiency. The TADF material transfers some triplet and singlet excitons to the phosphorescent material. Due to the orbital-spin coupling effect of heavy metals, the singlet and triplet energy levels of the phosphorescent material overlap, allowing it to transfer energy in singlet form to the multi-resonant fluorescent material. Furthermore, the TADF material also transfers some singlet and a small number of triplet excitons to the multi-resonant fluorescent material. Because the multi-resonant fluorescent material has weak TADF properties, the small number of triplet excitons it receives can be converted into singlet excitons. Theoretically, the energy in the phosphorescent and TADF materials is transferred to the multi-resonant fluorescent material without loss. As a highly efficient luminescent material, the multi-resonant fluorescent material can convert all energy into light emission in a timely manner, resulting in the highest device efficiency. In this invention, triplet excitons are converted into fast-emitting singlet excitons through the synergistic effect of TADF and phosphorescent materials, reducing the number of excitons inside the device and improving the device lifetime. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a light-emitting layer in existing technology;

[0012] Figure 2 This is a schematic diagram of the light-emitting layer in this invention;

[0013] Figure 3 This is a schematic diagram of the OLED device in this invention. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] A schematic diagram of the light-emitting layer in related technologies is shown below. Figure 1As shown, this is a TADF-sensitized multiple resonance fluorescent material. Although TADF-sensitized fluorescence has high color purity, it also suffers from the problem that high-energy triplet excitons on the TADF cannot be converted into singlet excitons in time, causing the OLED device to remain in a high-energy state for a long time, resulting in a low device lifetime. Simultaneously, since triplet excitons may be transferred to the fluorescent material via Dexter, this can degrade device performance. The TADF in the device transfers energy to the fluorescent material through the Foster mechanism. The stability and efficiency of this energy transfer process are related to the stability of the emission spectrum. There may be two emission mechanisms: TADF and fluorescence. Instability or poor stability of the emission spectrum is extremely detrimental to product manufacturing.

[0016] This invention provides a light-emitting layer, comprising:

[0017] TADF materials, phosphorescent materials, multiple resonance fluorescent materials, and host materials.

[0018] This invention incorporates phosphorescent materials into the emitting layer, enabling the reception of triplet excitons. These triplet excitons can then be transferred to the singlet energy levels of the multi-resonant fluorescent material, reducing the number of triplet excitons within the device and improving its lifetime. The multi-resonant fluorescent material can convert triplet excitons into singlet excitons while receiving a small number, thus improving device efficiency. Due to the dual quenching effect of the phosphorescent and multi-resonant fluorescent materials on the TADF material, the luminescence of the TADF material can be completely suppressed, improving the stability of the emission spectrum.

[0019] like Figure 2 As shown, in this invention, triplet excitons are converted into singlet excitons through the synergistic effect of TADF material, phosphorescent material, and multi-resonant fluorescent material, reducing the number of triplet excitons and improving device lifetime and efficiency. The TADF material transfers some triplet and singlet excitons to the phosphorescent material. Due to the orbital-spin coupling effect of heavy metals, the singlet and triplet energy levels of the phosphorescent material overlap, and the phosphorescent material transfers energy to the multi-resonant fluorescent material in singlet form. Furthermore, the TADF material also transfers some singlet and a small number of triplet excitons to the multi-resonant fluorescent material. Because the multi-resonant fluorescent material has weak TADF properties, the small number of triplet excitons it receives can be converted into singlet excitons. Theoretically, the energy in the phosphorescent and TADF materials is transferred to the multi-resonant fluorescent material without loss. As a highly efficient luminescent material, the multi-resonant fluorescent material can convert all the energy into light emission in a timely manner, resulting in the highest device efficiency. In this invention, triplet excitons are converted into fast-emitting singlet excitons through the synergistic effect of TADF and phosphorescent materials, reducing the number of excitons inside the device and improving the device lifetime.

[0020] In this invention, the TADF material is a material exhibiting thermo-induced delayed fluorescence. Optionally, the energy difference between the singlet and triplet states of the TADF material is <0.3 eV, such as 0.1 eV or 0.2 eV.

[0021] In this invention, the phosphorescent material is a material containing heavy metal elements that has a phosphorescent effect and plays the role of energy transmission intermediary. At the same time, triplet excitons and singlet excitons are impregnated and mixed to improve the exciton utilization rate.

[0022] In this invention, the multi-resonance fluorescent material acts as a luminescent material. It is a multi-resonance material and can convert some triplet excitons into singlet excitons. However, due to insufficient antisystem crossing rate, it is difficult to convert all triplet excitons into singlets, so its addition amount needs to be reduced.

[0023] In this invention, the main material is one or more materials that have hole transport and / or electron transport functions.

[0024] In this invention, optionally, the singlet energy level of the host material is higher than that of the TADF material, and the triplet energy level of the host material is higher than that of the TADF material; the singlet energy level of the TADF material is higher than that of the phosphorescent material, and the triplet energy level of the TADF material is higher than that of the phosphorescent material; the singlet energy level of the phosphorescent material is higher than that of the multi-resonance fluorescent material; and the triplet energy level of the phosphorescent material is higher than that of the multi-resonance fluorescent material.

[0025] In this invention, by employing the above-mentioned main material, TADF material, phosphorescent material, and multi-resonance fluorescent material with a single triplet energy level configuration, high-efficiency luminescence can be achieved.

[0026] In this invention, optionally, the HOMO energy level of the host material, TADF material, phosphorescent material, and multiple resonance fluorescent material gradually increases, while the LUMO energy level gradually decreases.

[0027] In this invention, optionally, the HOMO energy level difference between the host material and the TADF material is <0.1 eV, such as 0.02 eV, 0.04 eV, 0.06 eV, or 0.08 eV; the LUMO energy level difference is <0.1 eV, such as 0.02 eV, 0.04 eV, 0.06 eV, or 0.08 eV; and the HOMO energy level difference between the TADF material and the phosphorescent material is <0.1 eV, such as 0.02 eV, 0.04 eV, or 0.06 eV. eV, 0.08eV, LUMO energy level difference <0.1eV, such as 0.02eV, 0.04eV, 0.06eV, 0.08eV; HOMO energy level difference <0.1eV, such as 0.02eV, 0.04eV, 0.06eV, 0.08eV, LUMO energy level difference <0.1eV, such as 0.02eV, 0.04eV, 0.06eV, 0.08eV; phosphorescent materials and multiple resonance fluorescent materials have HOMO energy level difference <0.1eV, such as 0.02eV, 0.04eV, 0.06eV, 0.08eV.

[0028] In this invention, optionally, the energy level difference between the HOMO of the TADF material and the LUMO of the phosphorescent material is greater than 0.2 eV above the triplet energy level of the phosphorescent material, such as 0.3 eV, 0.4 eV, or 0.5 eV; and the energy level difference between the LUMO of the TADF material and the HOMO of the phosphorescent material is greater than 0.2 eV above the triplet energy level of the phosphorescent material, such as 0.3 eV, 0.4 eV, or 0.5 eV.

[0029] In this invention, optionally, the energy level difference between the HOMO of the TADF material and the LUMO of the multiple resonance fluorescent material is greater than 0.2 eV, such as 0.3 eV, 0.4 eV, or 0.5 eV, of the singlet energy level of the multiple resonance fluorescent material; and the energy level difference between the LUMO of the TADF material and the HOMO of the multiple resonance fluorescent material is greater than 0.2 eV, such as 0.3 eV, 0.4 eV, or 0.5 eV, of the singlet energy level of the multiple resonance fluorescent material.

[0030] In this invention, the HOMO and LUMO energy levels and triplet energy levels of the above-mentioned host material, TADF material, phosphorescent material, and multiple resonance fluorescent material are set. By controlling the HOMO, LUMO, and triplet energy levels between different materials, the formation of excitocomplexes is avoided to prevent energy deactivation.

[0031] In this invention, optionally, the emission peak of the TADF material is redshifted by less than 0.3 eV compared to the minimum absorption band peak of the phosphorescent material, such as 0.1 eV or 0.2 eV; the emission peak of the phosphorescent material is redshifted by less than 0.3 eV compared to the visible light absorption peak of the multiple resonance fluorescent material, such as 0.1 eV or 0.2 eV; and the emission peak of the TADF material is redshifted by less than 0.3 eV compared to the visible light absorption peak of the multiple resonance fluorescent material, such as 0.1 eV or 0.2 eV.

[0032] In this invention, by using the above-mentioned TADF material, phosphorescent material, and multiple resonance fluorescent material to set the emission peak, a smaller energy difference between the energy donor emission peak and the energy acceptor absorption peak can be generated, enabling efficient energy transfer within the luminescent layer.

[0033] In this invention, optionally, the TADF material has a structure of formula A:

[0034]

[0035] In Formula A, R1 to R6 are independently selected from hydrogen, deuterium, halogen, cyano, alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl. In this invention, the halogen in Formula A can be selected from F, the alkyl can be selected from methyl or CD3, the aryl can be selected from phenyl, and the heteroaryl can be selected from the following structures:

[0036]

[0037] In this invention, the TADF material may be selected from one or more of Formulas A-1 to A-20:

[0038]

[0039]

[0040]

[0041]

[0042] In this invention, optionally, the phosphorescent material has a structure of formula B:

[0043]

[0044] In Formula B, R7 to R9 are independently selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups.

[0045] In this invention, R7 to R9 can be independently selected from the following groups:

[0046]

[0047] In this invention, the phosphorescent material may be selected from one or more of Formulas B-1 to B-14:

[0048]

[0049]

[0050] In this invention, optionally, the multiple resonance fluorescent material has a C-structure:

[0051]

[0052] In formula C, R 10 ~R 16 Independently selected from hydrogen, deuterium, halogen, -B=, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

[0053] In this invention, the unsubstituted alkyl group in formula C can be selected from methyl or butyl, the substituted alkyl group can be selected from -Si(CH3)3, the aryl group can be selected from phenyl, and the heteroaryl group can be selected from the following structure:

[0054]

[0055] In this invention, the multiple resonance fluorescent material can be selected from one of formulas C-1 to C-19:

[0056]

[0057]

[0058]

[0059] In this invention, optionally, the main material has a structure of formula D:

[0060]

[0061] In formula D, Ar1 is selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups.

[0062] In this invention, Ar1 can be selected from the following structure:

[0063]

[0064] In this invention, the main material can be selected from one or more of the structures of formulas D-1 to D-32:

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] In this invention, the TADF material and the host material can be replaced by an excimer complex with TADF properties formed from a P-type host material and an N-type host material; the P-type host material is denoted as H1, and the N-type host material is denoted as H2; the LUMO, HOMO, and T1 energy level relationships of the P-type host material and the N-type host material satisfy the following condition to form an excimer complex:

[0072] Min{LUMO(H1)-HOMO(H2),LUMO(H2)-HOMO(H1)}≤

[0073] Min{T1(H1), T1(H2)}+0.1eV.

[0074] In this invention, optionally, the P-type main body material has a structure of formula E:

[0075]

[0076] In formula E, R1 to R9 are independently selected from substituted or unsubstituted C1 to C18 alkyl groups, optionally from substituted or unsubstituted C5 to C15 alkyl groups, optionally from substituted or unsubstituted C8 to C12 alkyl groups; substituted or unsubstituted C6 to C60 aryl groups, optionally from substituted or unsubstituted C10 to C50 aryl groups, optionally from substituted or unsubstituted C20 to C40 aryl groups, optionally from substituted or unsubstituted C30 aryl groups; substituted or unsubstituted C5 to C60 heteroaryl groups, optionally from substituted or unsubstituted C10 to C50 heteroaryl groups, optionally from substituted or unsubstituted C20 to C40 heteroaryl groups, optionally from substituted or unsubstituted C30 heteroaryl groups; substituted or unsubstituted The substituted deuterated C1-C18 alkyl group may be a self-substituted or unsubstituted deuterated C5-C15 alkyl group or a self-substituted or unsubstituted deuterated C8-C12 alkyl group; the substituted or unsubstituted deuterated C6-C60 aryl group may be a self-substituted or unsubstituted deuterated C10-C50 aryl group or a self-substituted or unsubstituted deuterated C20-C40 aryl group or a self-substituted or unsubstituted deuterated C30 aryl group; the substituted or unsubstituted deuterated C5-C60 heteroaryl group may be a self-substituted or unsubstituted deuterated C10-C50 heteroaryl group or a self-substituted or unsubstituted deuterated C20-C40 heteroaryl group or a self-substituted or unsubstituted deuterated C30 heteroaryl group.

[0077] In this invention, the substituted groups in R1 to R9 of formula E can be independently selected from fluorine, methyl, ethyl, tert-butyl, phenyl, naphthyl, phenanthryl, pyrene, pyridyl, quinolinyl, isoquinolinyl, phenanthridine, phenanthroline, carbazole, indolyl, thiophene, imidazolyl, thiazolyl, or pyrrole.

[0078] In this invention, the P-type main body material can be selected from one or more of Formulas E-1 to E-9:

[0079]

[0080]

[0081] In this invention, optionally, the N-type body material has a structure of formula F1 or F2:

[0082]

[0083] In formula F1, Ar2 is selected from naphthyl or N-substituted naphthyl;

[0084]

[0085] In formula F2, Ar3 is selected from phenyl or N-substituted phenyl.

[0086] In this invention, the N-type body material can be selected from one or more of formulas F-1 to F12:

[0087]

[0088]

[0089]

[0090]

[0091] In this invention, the mass ratio of the P-type main material to the N-type main material can be selected as (10-90):(90-10), (20-80):(80-20), (30-70):(70-30), (40-60):(60-40), or 50:50.

[0092] In this invention, the mass content of the TADF material in the luminescent layer can be selected as 10-60%, 20-50%, or 30-40%; the mass content of the phosphorescent material in the luminescent layer can be selected as 1-10%, 2-8%, or 3-6%; the mass content of the multiple resonance fluorescent material in the luminescent layer can be selected as 0.2-2%, 0.5-1.5%, or 0.8-1.2%; and the mass content of the host material in the luminescent layer can be selected as 10-80%, 20-60%, or 30-50%.

[0093] In this invention, the amount of multi-resonance fluorescent material added is reduced to about 1 wt%, which can weaken the process by which the host transfers triplet excitons to the multi-resonance fluorescent material through DEXTER energy transfer.

[0094] In this invention, the thickness of the light-emitting layer can be selected from 10 to 50 nm, 20 to 40 nm, or 30 nm.

[0095] In this invention, the method for preparing the light-emitting layer can be selected from one or more of thermal evaporation, thermal transfer and inkjet printing.

[0096] In this invention, during the thermal evaporation process, the raw materials for the light-emitting layer (including TADF material, phosphorescent material, multi-resonance fluorescent material and host material) can be heated to a set rate, the rate is maintained stable for 20 seconds, the evaporation baffle is opened, so that each material is deposited on the substrate, and the evaporation is stopped after the required film thickness is reached.

[0097] In this invention, during the thermal transfer process, heat is applied to the roll of light-emitting layer material (including TADF material, phosphorescent material, multi-resonance fluorescent material and host material) as the roll rotates close to the substrate, so that the dye is transferred onto the substrate.

[0098] In this invention, during the inkjet printing process, a solution of the light-emitting layer raw materials (including TADF material, phosphorescent material, multi-resonance fluorescent material and host material) can be sprayed onto the substrate by electrostatic attraction to form the desired light-emitting layer.

[0099] The present invention provides a light-emitting device, comprising: the light-emitting layer described in the above technical solution.

[0100] In this invention, the light-emitting device may further include:

[0101] One or more of the following: capping layer, cathode, electron injection layer, electron transport layer, hole blocking layer, electron blocking layer, hole transport layer, hole injection layer, and anode.

[0102] In this invention, the structure of the light-emitting device is as follows: Figure 3 As shown, it may include:

[0103] Anode (1);

[0104] A hole injection layer (2) is provided on the surface of the anode;

[0105] Hole transport layer (3) disposed on the surface of the hole transport layer;

[0106] An electron blocking layer (4) is disposed on the surface of the hole transport layer;

[0107] A light-emitting layer (5) disposed on the surface of the electron blocking layer;

[0108] Hole blocking layer (6) disposed on the surface of the light-emitting layer;

[0109] An electron transport layer (7) disposed on the surface of the hole blocking layer;

[0110] An electron injection layer (8) is disposed on the surface of the electron transport layer;

[0111] A cathode (9) disposed on the surface of the electron injection layer;

[0112] A capping layer (10) is disposed on the cathode surface.

[0113] In this invention, the anode can be a composite anode of ITO / silver / ITO; the silver film thickness can be 100-200 nm, 120-180 nm, or 140-160 nm; the ITO film thickness can be 5-200 nm, 10-180 nm, 30-150 nm, 50-120 nm, or 80-100 nm.

[0114] In this invention, the material of the hole injection layer can be selected from compounds such as HTACN, axialene, and phthalocyanine bronze; the thickness of the hole injection layer can be selected from 1 to 50 nm, 5 to 40 nm, 10 to 30 nm, or 20 nm.

[0115] In this invention, the material of the hole transport layer can be selected from aromatic amine organic compounds such as NPB and NPD; the thickness of the hole transport layer can be selected from 10-200 nm, 20-150 nm, 50-120 nm, or 80-100 nm.

[0116] In this invention, the material of the electron blocking layer can be selected from carbazole compounds containing high singlet triplet energy levels, such as TCTA; the thickness of the electron blocking layer can be selected from 1 to 50 nm, 5 to 40 nm, 10 to 30 nm, or 20 nm.

[0117] In this invention, the light-emitting layer is consistent with the above-described technical solution, and will not be repeated here.

[0118] In this invention, the material of the hole transport layer can be selected from amine compounds such as TPBI; the thickness of the hole transport layer can be selected from 1 to 10 nm, 2 to 8 nm, 3 to 6 nm, or 4 to 5 nm.

[0119] In this invention, the material of the electron transport layer can be selected from triazine compounds; the thickness of the electron transport layer can be selected from 10 to 50 nm, 20 to 40 nm, or 30 nm.

[0120] In this invention, the material of the electron injection layer can be selected from compounds such as lithium fluoride and ytterbium; the thickness of the electron injection layer can be selected from 1 to 10 nm, 2 to 8 nm, 3 to 6 nm, or 4 to 5 nm.

[0121] In this invention, the cathode material can be selected from silver or a magnesium-silver alloy; the thickness of the cathode can be selected from 10-20 nm, 12-18 nm, or 14-16 nm.

[0122] In this invention, the material of the capping layer can be selected from compounds with high refractive index and high ultraviolet light absorption; the thickness of the capping layer can be selected from 10 to 100 nm, 20 to 80 nm, 30 to 60 nm, or 40 to 50 nm.

[0123] The present invention provides a light-emitting device, comprising: the light-emitting device described in the above technical solution.

[0124] In this invention, the light-emitting device may be a self-emissive display and / or a lighting device.

[0125] Example 1

[0126] The light-emitting device was prepared according to the following method:

[0127] After ultrasonic cleaning and drying, the glass substrate is placed into a vapor deposition chamber pre-filled with various materials. First, HATCN is heated to 0.1 nm / s and then deposited at a thickness of 10 nm. Then, NPB is heated to 0.1 nm / s and deposited at a thickness of 60 nm. MCP is heated to 0.04 nm / s, 4CzIPN to 0.054 nm / s, Ir(ppy)3 to 0.0055 nm / s, BBCZ to 0.0005 nm / s and deposited at a thickness of 35 nm. Beqp2 is heated to 0.1 nm / s and deposited at a thickness of 30 nm. LiF is heated to 0.01 nm / s and deposited at a thickness of 1 nm. Aluminum is heated to 0.5 nm / s and deposited at a thickness of 100 nm.

[0128] The structure of the light-emitting device prepared in Example 1 of this invention is: HTACN(10) / NPB(60) / 2-TNATA(10) / MCP:4CzIPN:Ir(ppy)3:BBCZ(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0129]

[0130] Example 2

[0131] The light-emitting device was prepared according to the following method:

[0132] After ultrasonic cleaning and drying, the glass substrate is placed into a vapor deposition chamber pre-filled with various materials. First, HATCN is heated to 0.1 nm / s and then vapor-deposited at a thickness of 10 nm. Then, NPB is heated to 0.1 nm / s and vapor-deposited at a thickness of 60 nm. BBBC is heated to 0.04 nm / s, compound F-1 to 0.054 nm / s, Ir(ppy)3 to 0.0055 nm / s, and BBCZ to 0.0005 nm / s and vapor-deposited at a thickness of 35 nm. Beqp2 is heated to 0.1 nm / s and vapor-deposited at a thickness of 30 nm. LiF is heated to 0.01 nm / s and vapor-deposited at a thickness of 1 nm. Aluminum is heated to 0.5 nm / s and vapor-deposited at a thickness of 100 nm.

[0133] The structure of the light-emitting device prepared in Example 2 of this invention is: HTACN(10) / NPB(60) / 2-TNATA(10) / BBBC:compound F-1:Ir(ppy)3:BBCZ(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0134]

[0135] Examples 3-7

[0136] The light-emitting device was prepared according to the method of Example 1, except that the material of the light-emitting layer is different from that of Example 1, as detailed below:

[0137] The structure of the light-emitting device prepared in Example 3 is as follows:

[0138] HTACN(10) / NPB(60) / 2-TNATA(10) / HOST1(compound D-1):TADF1(compound A-1):PhD1(compound B-1):FD1(compound C-1)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0139] The structure of the light-emitting device prepared in Example 4 is as follows:

[0140] HTACN(10) / NPB(60) / 2-TNATA(10) / HOST2(compound D-2):TADF2(compound A-2):PhD2(compound B-2):FD2(compound C-2)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0141] The structure of the light-emitting device prepared in Example 5 is as follows:

[0142] HTACN(10) / NPB(60) / 2-TNATA(10) / HOST3(compound D-3):TADF3(compound A-3):PhD3(compound B-3):FD3(compound C-3)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0143] The structure of the light-emitting device prepared in Example 6 is as follows:

[0144] HTACN(10) / NPB(60) / 2-TNATA(10) / HOST4(compound D-4):TADF4(compound A-4):PhD4(compound B-4):FD4(compound C-4)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0145] The structure of the light-emitting device prepared in Example 7 is as follows:

[0146] HTACN(10) / NPB(60) / 2-TNATA(10) / HOST5(compound D-5):TADF5(compound A-5):PhD5(compound B-5):FD5(compound C-5)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0147] Examples 8-12

[0148] The light-emitting device was prepared according to the method of Example 2, except that the material of the light-emitting layer is different from that of Example 2, as detailed below:

[0149] The structure of the light-emitting device prepared in Example 8 is as follows:

[0150] HTACN(10) / NPB(60) / 2-TNATA(10) / P-HOST1(compound E-1):N-HOST1(compound F-1):PhD1(compound B-1):FD1(compound C-1)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0151] The structure of the light-emitting device prepared in Example 9 is as follows:

[0152] HTACN(10) / NPB(60) / 2-TNATA(10) / P-HOST2(compound E-2):N-HOST2(compound F-2):PhD2(compound B-2):FD2(compound C-2)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0153] The structure of the light-emitting device prepared in Example 10 is as follows:

[0154] HTACN(10) / NPB(60) / 2-TNATA(10) / P-HOST3(compound E-3):N-HOST3(compound F-3):PhD3(compound B-3):FD3(compound C-3)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0155] The structure of the light-emitting device prepared in Example 11 is as follows:

[0156] HTACN(10) / NPB(60) / 2-TNATA(10) / P-HOST4(compound E-4):N-HOST4(compound F-4):PhD4(compound B-4):FD4(compound C-4)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0157] The structure of the light-emitting device prepared in Example 12 is as follows:

[0158] HTACN(10) / NPB(60) / 2-TNATA(10) / P-HOST5(compound E-5):N-HOST5(compound F-5):PhD5(compound B-5):FD5(compound C-5)(40:54:5.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0159] Comparative Examples 1-2

[0160] The light-emitting device was prepared according to the method of Example 1, except that the material of the light-emitting layer is different from that of Example 1, as detailed below:

[0161] The structure of the light-emitting device prepared in Comparative Example 1 is: HTACN(10) / NPB(60) / 2-TNATA(10) / MCP:4CzIPN:BBCZ(40:59.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0162] The structure of the light-emitting device prepared in Comparative Example 2 is: HTACN(10) / NPB(60) / 2-TNATA(10) / MCP:BBCZ(0.5%,35) / Bepq2(30) / LiF(1) / Al(100).

[0163] Comparative Example 3

[0164] The light-emitting device was prepared according to the method of Example 2, except that the material of the light-emitting layer is different from that of Example 2, as detailed below:

[0165] The structure of the light-emitting device prepared in Comparative Example 3 is as follows:

[0166] HTACN(10) / NPB(60) / 2-TNATA(10) / BBBC:Compound F-1:BBCZ(40:59.5:0.5,35) / Bepq2(30) / LiF(1) / Al(100).

[0167] Performance testing

[0168] The photoelectric performance of the light-emitting devices prepared in the embodiments and comparative examples of this invention was tested. The spectrophotometer used for testing was a Konica Minolta CS2000, and the current source was a Keithley 2400; the test was conducted at a constant 10 mA / cm². 2 Driven by a certain current density, the device performance is as follows. The external quantum efficiency of the device is calculated based on the obtained spectrum, and the device lifetime is 50 mA / cm². 2 Tested at current density:

[0169]

[0170]

[0171] The raw materials used in the examples were dissolved in toluene to form approximately 1x10⁻⁶. -7 mol / L solution; UV absorption peaks of the material were tested using a Shimadzu UV-1780 spectrometer; fluorescence peaks of the material were tested using a Hitachi F4600 fluorescence spectrometer; phosphorescence peaks of the material were tested using the F4600 in phosphorescence mode under liquid nitrogen cooling; the results are as follows:

[0172] compound Ultraviolet absorption peak (eV) Fluorescence peak (eV) 77K phosphorescence peak (eV) A-1 2.43 2.41 A-2 2.38 2.28 A-3 2.46 2.43 A-4 2.51 2.36 A-5 2.39 2.33 B-1 2.52 2.36 2.36 B-2 2.48 2.33 2.33 B-3 2.39 2.29 2.29 B-4 2.49 2.31 2.31 B-5 2.5 2.36 2.36 C-1 2.37 2.29 1.95 C-2 2.34 2.24 1.78 C-3 2.36 2.25 1.9 C-4 2.32 2.27 2 C-5 2.33 2.26 1.89 D-1 3.1 2.67 D-2 3.2 2.77 D-3 3.26 2.8 D-4 3.42 2.92 D-5 3.56 2.9

[0173] Using a Chenhua CHI660 electrochemical workstation with ferrocene as an internal standard, the HOMO / LUMO energy levels of the material used in the example were tested. 0.1 g of the material was dissolved in a pre-prepared tetrabutylhexafluorophosphate tetrahydrofuran solution, and nitrogen gas was continuously purged to remove oxygen from the solution. The test results are as follows:

[0174] compound HOMO level (eV) LUMO level (eV) A-1 -5.33 -2.2 A-2 -5.27 -2.38 A-3 -5.26 -2.27 A-4 -5.21 -2.29 A-5 -5.3 -2.31 B-1 -5.20 -2.36 B-2 -5.18 -2.31 B-3 -5.19 -2.32 B-4 -5.17 -2.31 B-5 -5.19 -2.34 C-1 -5.07 -2.42 C-2 -5.02 -2.39 C-3 -5.01 -2.37 C-4 -5.09 -2.33 C-5 -5.1 2.38 D-1 -5.44 -1.98 D-2 -5.46 -1.87 D-3 -5.39 -2.1 D-4 -5.55 -2.31 D-5 -5.48 -2.08

[0175] In Example 1, the emission peak value of the 4CzIPN material is within 0.3 eV of the minimum absorption band peak redshift compared to Ir(ppy)3; the emission peak value of the 4CzIPN material is within 0.3 eV of the absorption peak redshift compared to the BBCz material, and the emission peak value of the Ir(ppy)3 material is within 0.3 eV of the absorption peak redshift compared to the BBCz material in the visible light band. This smaller energy difference between the energy donor emission peak and the energy acceptor absorption peak allows for efficient energy transfer within the luminescent layer. The HOMO energy level difference between the MCP material and the LUMO energy level of the 4CzIPN material is 0.1 eV higher than the triplet energy level of the 4CzIPN material; the LUMO energy level difference between the MCP material and the HOMO energy level of the 4CzIPN material is more than 0.1 eV higher than the triplet energy level of the 4CzIPN material; the HOMO energy level difference between the 4CzIPN material and the LUMO energy level of the Ir(ppy)3 material is more than 0.1 eV higher than the triplet energy level of the Ir(ppy)3 material; the LUMO energy level difference between the 4CzIPN material and the LUMO energy level of the Ir(ppy)3 material is more than 0.1 eV higher than the triplet energy level of the Ir(ppy)3 material; the LUMO energy level difference between the 4CzIPN material and the 4CzIPN material is more than 0.1 eV higher than the triplet energy level of the Ir(ppy)3 material. The HOMO energy level difference between the 4CzIPN material and the Ir(ppy)3 material is 0.1 eV higher than the triplet energy level of the Ir(ppy)3 material; the LUMO energy level difference between the 4CzIPN material and the BBCz material is more than 0.1 eV higher than the triplet energy level of the BBCz material; the LUMO energy level difference between the 4CzIPN material and the HOMO energy level of the BBCz material is more than 0.1 eV higher than the triplet energy level of the BBCz material. By controlling the HOMO, LUMO, and triplet energy levels between different materials, the formation of excitocomplexes is avoided to prevent energy deactivation. The singlet energy level of MCP is > the singlet energy level of 4CzIPN > the singlet energy level of Ir(ppy)3 > the singlet energy level of BBCz, and the triplet energy level of MCP is > the triplet energy level of 4CzIPN > the triplet energy level of Ir(ppy)3 > the triplet energy level of BBCz. By setting a single triplet energy level in the material, high-efficiency luminescence is achieved. The difference between the HOMO energy level of the MCP and the HOMO energy level of the electron blocking layer is within 0.3 eV, enabling efficient hole injection.

[0176] In other embodiments, the singlet and triplet energy levels, and the singlet energy levels of the host material, TADF, phosphorescent material, and multiple resonance fluorescent material, increase sequentially, conforming to the energy level relationship between the four materials in this invention. The HOMO energy level increases sequentially along the singlet energy levels of the host material, TADF, phosphorescent material, and multiple resonance fluorescent material, while the LUMO energy level decreases sequentially along the singlet energy levels of the host material, TADF, phosphorescent material, and multiple resonance fluorescent material, and the energy level differences basically conform to the relationship between the four materials in this invention. The energy differences between the absorption peaks and fluorescence peaks of the materials also conform to the 0.3 eV setting in this invention. This invention can achieve the aforementioned relatively superior device.

[0177] In Example 1, MCP acts as a hole transporter, 4CzIPN acts as a TADF, and Ir(ppy)3 acts as an energy transport mediator. Simultaneously, it impregnates and mixes triplet and singlet excitons to improve exciton utilization. BBCz acts as a luminescent material, being a multi-resonance material that can convert some triplet excitons into singlet states. However, due to insufficient antisystem crossover rate, it is difficult to convert all triplet excitons into singlet states. Therefore, its addition amount needs to be reduced to about 1% to weaken the process of transferring triplet excitons to BBCz via DEXTER energy transfer.

[0178] The TADF material with the excitocomplex mechanism was also tested, and the phosphorescence peak energy was found when the triplet energy level was 77K.

[0179] The TADF material conforming to the excitocomplex mechanism in the embodiments of the present invention was also tested, and the phosphorescence peak energy was measured at 77 K for the triplet energy level; the test results are as follows:

[0180] compound triplet energy level (eV) HOMO level (eV) LUMO level (eV) E-1 2.44 -5.26 -2.33 E-2 2.24 -5.23 -2.35 E-3 2.31 -5.16 -2.26 E-4 2.28 -5.25 -2.31 E-5 2.51 -5.26 -2.22 F-1 2.42 -5.03 -2.86 F-2 2.31 -5.17 -2.93 F-3 2.37 -5.22 -2.82 F-4 2.30 -5.19 -2.93 F-5 2.53 -5.25 -2.73

[0181] In Example 2, the energy level relationship between the BBBC material and compound F-1 satisfies 2.55 < 2.52 + 0.1, forming a TADF excimer complex. The emission peak of the excimer complex is within 0.3 eV redshift of the minimum absorption band peak compared to Ir(ppy)3. The emission spectrum of the excimer complex is within 0.3 eV redshift of the absorption peak compared to BBCz material, and the emission spectrum of Ir(ppy)3 material is within 0.3 eV redshift of the visible light absorption peak compared to BBCz material. This small energy difference between the energy donor emission peak and the energy acceptor absorption peak enables efficient energy transfer within the luminescent layer. The singlet energy level of the excimer complex > the singlet energy level of Ir(ppy)3 > the singlet energy level of BBCz, and the triplet energy level of the excimer complex > the triplet energy level of Ir(ppy)3 > the triplet energy level of BBCz. By setting a single triplet energy level in the material, high-efficiency luminescence is achieved. The HOMO energy level of the BBBC material is within 0.3 eV of the HOMO energy level of the electron blocking layer, while the LUMO energy level of the compound F-1 material is between 0.3 eV and the hole blocking layer. These energy levels transport holes and electrons respectively, thus balancing the carriers inside the luminescent layer.

[0182] In other embodiments, the energy level data of the P-type and N-type host materials meet the conditions set in this invention, and the TADF characteristic device based on the excitocomplex can also achieve good results.

[0183] Comparative Example 2 uses a pure fluorescent material device with low efficiency; Comparative Examples 1 and 3 use conventional superfluorescent materials, which also have poor efficiency and lifetime. The efficiency and lifetime of the light-emitting device prepared in the embodiments of this invention are significantly improved. In this invention, the combined effect of phosphorescent material, multi-resonance fluorescent material, and TADF material improves the efficiency and lifetime of the device; the energy level matching of phosphorescent material, multi-resonance fluorescent material, and TADF material gives the device better performance; and the use of exciton complexes to form materials with TADF properties can also improve the device efficiency and lifetime.

[0184] While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be readily understood by those skilled in the art that various changes may be made to suit particular circumstances, materials, compositions, substances, methods, or processes to the objectives, spirit, and scope of this application without departing from the true spirit and scope of the invention as defined by the appended claims. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. A light-emitting layer, comprising: TADF materials, phosphorescent materials, multiple resonance fluorescent materials, and host materials; The TADF material and the host material are replaced by an excitocomplex with TADF properties formed by a P-type host material and an N-type host material; The P-type host material is denoted as H1, and the N-type host material is denoted as H2; the LUMO, HOMO, and T1 energy level relationships of the P-type and N-type host materials satisfy the following condition: Min{LUMO(H1)-HOMO(H2),LUMO(H2)-HOMO(H1)}≤ Min{T1(H1),T1(H2)}+0.1eV; The P-type main material has a structure of formula E: Formula E; In Formula E, R1 to R9 are independently selected from substituted or unsubstituted C1 to C18 alkyl, substituted or unsubstituted C6 to C60 aryl, substituted or unsubstituted C5 to C60 heteroaryl, substituted or unsubstituted deuterated C1 to C18 alkyl, substituted or unsubstituted deuterated C6 to C60 aryl, and substituted or unsubstituted deuterated C5 to C60 heteroaryl; The N-type main material has a structure of formula F1 or F2: Formula F1; In formula F1, Ar2 is selected from naphthyl or N-substituted naphthyl; Formula F2; In formula F2, Ar3 is selected from phenyl or N-substituted phenyl.

2. The light-emitting layer according to claim 1, characterized in that, The singlet energy level of phosphorescent materials is higher than that of multiple resonance fluorescent materials; the triplet energy level of phosphorescent materials is higher than that of multiple resonance fluorescent materials.

3. The light-emitting layer according to claim 1, characterized in that, The HOMO energy level of the host material, TADF material, phosphorescent material, and multiple resonance fluorescent material gradually increases, while the LUMO energy level gradually decreases.

4. The light-emitting layer according to claim 1, characterized in that, The energy difference between the HOMO level and the LUMO level of phosphorescent materials and multiple resonance fluorescent materials is <0.1 eV.

5. The light-emitting layer according to claim 1, characterized in that, The emission peak of phosphorescent materials is redshifted by within 0.3 eV compared to the visible light absorption peak of multiple resonance fluorescent materials.

6. The light-emitting layer according to claim 1, characterized in that, The phosphorescent material has a structure of formula B: Formula B; In Formula B, R7 to R9 are independently selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups.

7. The light-emitting layer according to claim 6, characterized in that, The R7 to R9 groups are independently selected from the following formula: 、 、 、 、 、 、 、 、 、 、 、 。 8. The light-emitting layer according to claim 7, characterized in that, The phosphorescent material is selected from one or more of formulas B-1 to B-14: 。 9. The light-emitting layer according to claim 1, characterized in that, The fluorescent material with multiple resonances has a C-structure: Formula C; In formula C, R 10 ~R 16 Independently selected from hydrogen, deuterium, halogen, -B=, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

10. The light-emitting layer according to claim 9, characterized in that, In formula C, the unsubstituted alkyl group is selected from methyl or butyl, the substituted alkyl group is selected from -Si(CH3)3, the aryl group is selected from phenyl, and the heteroaryl group is selected from the following structures: 、 、 、 、 、 、 。 11. The light-emitting layer according to claim 10, characterized in that, The fluorescent material with multiple resonances is selected from one of formulas C-1 to C-19: Formula C-19.

12. The light-emitting layer according to claim 1, characterized in that, The substituted groups in R1 to R9 are selected from fluorine, methyl, ethyl, tert-butyl, phenyl, naphthyl, phenanthryl, pyrene, pyridyl, quinolinyl, isoquinolinyl, phenanthridine, phenanthroline, carbazole, indolyl, thiophene, imidazolyl, thiazolyl, or pyrrole.

13. The light-emitting layer according to claim 12, characterized in that, The P-type main body material is selected from one or more of formulas E-1 to E-9: E-1; E-2; Formula E-3; Formula E-4; Formula E-5; Formula E-6; Formula E-7; Formula E-8; Formula E-9.

14. The light-emitting layer according to claim 1, characterized in that, The N-type main material is selected from one or more of formulas F-1 to F12: Formula F-1 F-2 Type F-3 Type F-4 Type F-5 Type F-6 Type F-7 Type F-8 Type F-9 Type F-10 Type F-11 Formula F-12.

15. The light-emitting layer according to claim 1, characterized in that, The mass ratio of the P-type main material to the N-type main material is (10~90):(90~10).

16. The light-emitting layer according to claim 1, characterized in that, The TADF material has a mass content of 10-60% in the luminescent layer; the phosphorescent material has a mass content of 1-10% in the luminescent layer; the multiple resonance fluorescent material has a mass content of 0.2-2% in the luminescent layer; and the host material has a mass content of 10-80% in the luminescent layer.

17. The light-emitting layer according to claim 1, characterized in that, The thickness of the light-emitting layer is 10~50nm.

18. A light-emitting device, comprising: The light-emitting layer according to any one of claims 1 to 17.

19. A light-emitting device, comprising: The light-emitting device according to claim 18.

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