Composition for organic light emitting diode and use thereof

Abstract

The application discloses a composition for an organic light emitting diode and application thereof. The composition comprises a TADF material and a triplet exciton releasing agent; wherein the triplet exciton energy of the triplet exciton releasing agent is less than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releasing agent is greater than the singlet exciton energy of the TADF material, and the decay lifetime of the triplet exciton of the triplet exciton releasing agent is less than the decay lifetime of the triplet exciton of the TADF material. The application can improve the efficiency decay and improve the lifetime of the organic light emitting diode.

Description

Technical Field

[0001] This application relates to the field of display technology, and more specifically to a composition for organic light-emitting diodes and its application. Background Technology

[0002] After decades of development, Organic Light-Emitting Diode (OLED) display technology is increasingly replacing Liquid Crystal Display (LCD) technology. To date, OLED light-emitting materials have evolved to the third generation: the first generation used fluorescent materials, the second generation used phosphorescent materials, and the third generation uses thermally activated delayed fluorescence (TADF) materials. Currently, commercially available OLEDs primarily use first-generation fluorescent materials and second-generation phosphorescent materials; third-generation TADF materials have not yet entered mass production.

[0003] TADF materials have many advantages, including simple synthesis, low cost, easily tunable spectrum, high luminous efficiency, and the ability of TADF-OLEDs to achieve an internal quantum efficiency of 100%. However, for TADF-OLEDs, the long triplet exciton decay lifetime of TADF materials, typically on the order of 10 to 100 microseconds (μs), makes them prone to adverse processes such as triplet-singlet annihilation, triplet-triplet annihilation, and triplet-polaron annihilation. This often results in significant efficiency roll-off and low lifetime for TADF-OLEDs. Summary of the Invention

[0004] To address the problem of long triplet exciton decay lifetime in TADF materials leading to efficiency degradation and low lifetime, this application provides a composition for organic light-emitting diodes and its application.

[0005] This application provides a composition for an organic light-emitting diode (OLED), the composition comprising a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material.

[0006] Optionally, in some embodiments, the ratio of the triplet exciton decay lifetime of the triplet exciton releaser to the triplet exciton decay lifetime of the TADF material is 1:(3-9).

[0007] Optionally, in some embodiments, the triplet exciton releaser has a triplet exciton decay lifetime of less than or equal to 1 μs.

[0008] Optionally, in some embodiments, the triplet exciton releaser is selected from at least one of cyclooctatetraene, dinaphthalene, and 4,4'-bis[(N-carbazole)styryl]biphenyl; and / or,

[0009] The TADF material is selected from at least one of TMCz-BO, ν-DABNA, DMAC-TRZ, TBP-DMAc, 4CzFCN, t4CzIPN, and B-oCz.

[0010] Optionally, in some embodiments, the composition further includes a host material, the host material having a molar percentage of 0 to 89%, the TADF material having a molar percentage of 10% to 99%, and the triplet exciton releaser having a molar percentage of 1% to 70%.

[0011] Optionally, in some embodiments, the host material is selected from at least one of mCBP, CBP, PPF, CzSi, DCzPPY and DPEPO.

[0012] Optionally, in some embodiments, the composition comprises a TADF material and a triplet exciton releaser; wherein, in molar percentage, the triplet exciton releaser is 1% to 70%, and the TADF material is 30% to 99%; or,

[0013] The composition comprises a host material, a TADF material, and a triplet exciton releaser; wherein, by molar percentage, the host material comprises 20% to 89%, the TADF material comprises 10% to 30%, and the triplet exciton releaser comprises 1% to 50%.

[0014] This application also provides an ink comprising any of the compositions and solvents described above for organic light-emitting diodes.

[0015] This application also provides an organic light-emitting diode, which includes a cathode, an anode, and a light-emitting layer, wherein the light-emitting layer is disposed between the cathode and the anode, and the light-emitting layer comprises any of the compositions for organic light-emitting diodes described above.

[0016] This application also provides a method for fabricating an organic light-emitting diode, which includes the following steps:

[0017] Provide cathode;

[0018] A light-emitting layer is fabricated on the cathode. The light-emitting layer comprises a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material.

[0019] An anode is prepared on the light-emitting layer;

[0020] Alternatively, provide an anode;

[0021] A light-emitting layer is prepared on the anode, the light-emitting layer comprising a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material; and

[0022] A cathode is fabricated on the light-emitting layer.

[0023] The triplet exciton release agent used in this application embodiment can capture triplet excitons generated by TADF material, causing some of the triplet excitons generated in TADF to transfer to the release agent molecule, and de-excite some of the triplet excitons at a faster rate, causing the triplet excitons to decay rapidly, effectively reducing the number of triplet excitons, thereby greatly reducing the annihilation process between triplet excitons and singlet excitons, triplet excitons, and charge polarons, improving the efficiency decay of organic light-emitting diodes, and increasing the lifetime of organic light-emitting diodes. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the energy levels of the light-emitting mechanism of existing organic light-emitting diodes and the organic light-emitting diodes provided in the embodiments of this application;

[0026] Figure 2 This is a schematic diagram of the structure of the organic light-emitting diode provided in the first embodiment of this application;

[0027] Figure 3This is a schematic diagram of the structure of the organic light-emitting diode provided in the second embodiment of this application;

[0028] Figure 4 This is a flowchart of a method for fabricating an inverted organic light-emitting diode according to an embodiment of this application;

[0029] Figure 5 This is a flowchart of a method for fabricating a positive-type organic light-emitting diode according to an embodiment of this application;

[0030] Figure 6 These are the current efficiency-brightness curves of the TADF-OLEDs prepared in Examples 1, 2 and Comparative Example 1 of this application;

[0031] Figure 7 This is a lifetime curve of the TADF-OLED prepared in Examples 1, 2 and Comparative Example 1 of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] This application provides a composition for organic light-emitting diodes and its application. Detailed descriptions follow. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0034] This application provides a composition for an organic light-emitting diode (OLED), the composition comprising a TADF material and a triplet exciton releaser; wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the decay lifetime of the triplet exciton of the triplet exciton releaser is less than the decay lifetime of the triplet exciton of the TADF material.

[0035] It should be noted that the decay lifetime of the triplet exciton refers to the time during which the triplet exciton decays by 1 / e.

[0036] Please see Figure 1 , Figure 1 Figure (a) shows the energy level diagram of the light emission mechanism of existing TADF-OLEDs. In (a), S0 represents the singlet ground state energy of the TADF material, S1 represents the singlet exciton energy of the TADF material, and T1 represents the triplet exciton energy of the TADF material. RISC stands for reverse intersystem crossing. The energy of the triplet exciton formed at T1 is lost through radiative decay. Figure 1 (b) is a schematic diagram of the energy levels of the light-emitting mechanism of the organic light-emitting diode provided in this embodiment of the application. In (b), S0 represents the singlet ground state energy of the TADF material, S1 represents the singlet exciton energy of the TADF material, and T1 represents the triplet exciton energy of the TADF material. In (b), S0′ represents the singlet ground state energy of the triplet exciton releaser, S1′ represents the singlet exciton energy of the triplet exciton releaser, and T1′ represents the triplet exciton energy of the triplet exciton releaser. Figure 1 As shown in (b), when a large number of triplet excitons accumulate in the TADF material and a triplet exciton releaser is present, since the triplet exciton energy T1 of the TADF material is greater than the triplet exciton energy T1′ of the triplet exciton releaser, a portion of the triplet excitons in the TADF material will transfer to the triplet exciton releaser. Simultaneously, the singlet exciton energy S1′ of the triplet exciton releaser is greater than the singlet exciton energy S1 of the TADF material, preventing the transfer of singlet exciton energy from the TADF material to the triplet exciton releaser and thus reducing device efficiency. Furthermore, since the triplet exciton decay lifetime of the triplet exciton releaser is smaller than that of the TADF material, the triplet exciton releaser has a faster decay rate, causing these triplet excitons to undergo thermal relaxation more quickly and dissipate back to the ground state, thereby mitigating triplet exciton annihilation and improving efficiency decay and lifetime.

[0037] In some embodiments of this application, the triplet exciton decay lifetime of the TADF material is more than three times that of the triplet exciton releaser. A smaller decay lifetime of the triplet exciton releaser facilitates faster thermal relaxation of triplet excitons, leading to their dissipation back to the ground state and mitigating triplet exciton annihilation, thus improving efficiency degradation and increasing lifetime. In some embodiments, the ratio of the triplet exciton decay lifetime of the triplet exciton releaser to that of the TADF material is 1:(3-9). In other embodiments, the ratio is 1:(3.75-9). It is understood that the ratio of the triplet exciton decay lifetime of the triplet exciton releaser to the triplet exciton decay lifetime of the TADF material can be any value above 1:3, such as 1:3, 1:3.75, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:15, 1:50, 1:100, etc.

[0038] In some embodiments of this application, the triplet exciton releaser has a triplet exciton decay lifetime of less than or equal to 1 μs. This embodiment achieves the purpose of effectively releasing triplet excitons by controlling the triplet exciton decay lifetime of the triplet exciton releaser to 1 μs or less. It is understood that the triplet exciton decay lifetime of the triplet exciton releaser can be 1 μs or less than 1 μs, for example, it can be 0.01 μs to 0.9 μs, 0.01 μs to 0.5 μs, 0.01 μs to 0.2 μs, or 0.01 μs to 0.1 μs.

[0039] In other embodiments of this application, the triplet exciton releaser has a triplet exciton decay lifetime on the order of 0.2 μs. This embodiment, by controlling the triplet exciton decay lifetime of the triplet exciton releaser to 0.2 μs or less, can significantly alleviate the triplet exciton annihilation phenomenon in the emissive layer, thus significantly improving the OLED's lifetime. While there is some loss in OLED efficiency, it is minimal. It is understood that the triplet exciton decay lifetime of the triplet exciton releaser can be 0.2 μs or less, for example, it can be from 0.01 μs to 0.2 μs, or even from 0.01 μs to 0.1 μs.

[0040] In some embodiments of this application, the triplet exciton releaser is selected from at least one of cyclooctatetraene (COT), perylene, and BSBCz (4,4'-bis[(N-carbazole)styryl]biphenyl). The τ of COT...T Approximately 0.1 μs. The τ of the Perylene... T Approximately 0.2 μs. The τ of the BSBCz T Approximately 0.2 μs. It should be noted that τ in this embodiment and in the following embodiments... T This represents the decay lifetime of the triplet exciton.

[0041] In some embodiments of this application, the TADF material is selected from at least one of TMCz-BO, ν-DABNA, DMAC-TRZ, TBP-DMAc, 4CzFCN, t4CzIPN, and B-oCz.

[0042] The chemical structural formula of the TMCz-BO is as follows:

[0043] The τ of TMCz-BO T It is approximately 0.75 μs.

[0044] The chemical structural formula of the ν-DABNA is:

[0045] The τ of ν-DABNA T It is approximately 4.1 μs.

[0046] The Chinese name of the DMAC-TRZ is 10-(4-(4,6-diphenyl-1,3,5-triazol-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine, and its chemical structural formula is:

[0047] The DMAC-TRZ's τ T It is approximately 1.9 μs.

[0048] The English name of the TBP-DMAc is benzene-1,3,5-triyltris((4-(9,9-dimethylacridin-10(9H)-yl)phenyl)methanone, and its structural formula is:

[0049] The τ of the TBP-DMAc T It is approximately 5.6 μs.

[0050] The English name of the 4CzFCN is 2,3,4,6-Tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile, and its chemical structural formula is:

[0051] The τ of the 4CzFCN T It is approximately 3.3 μs.

[0052] The English name of t4CzIPN is 2,4,5,6-tetra(3,6-di-tert-butylcarbazol-9-yl)-1,3-dicyanobenzene, and its chemical structural formula is:

[0053] The τ of t4CzIPN T It is approximately 2.9 μs.

[0054] The chemical structural formula of B-oCz is:

[0055] The τ of B-oCz T It takes approximately 1.8 μs.

[0056] In some embodiments of this application, the composition further comprises a host material. In some embodiments of this application, the host material is selected from at least one of mCBP (3,3'-bis(9H-carbazole-9-yl)-1,1'-biphenyl), CBP (4,4'-bis(9-carbazole)biphenyl), PPF (2,8-bis(diphenylphosphoxy)dibenzofuran), CzSi (bis(4-(9H-carbazole-9-yl)phenyl)diphenylsilane), DCZPPY, and DPEPO (bis[2-((oxo)diphenylphosphino)phenyl] ether). It should be noted that DCZPPY is selected from 26DczPPy (2,6-bis(3-(9-carbazole)phenyl)pyridine), 35DczPPy (3,5-bis((9H-carbazole-9-yl)-3,1-phenylene)pyridine), or a mixture of 6DczPPy and 35DczPPy.

[0057] In some embodiments of this application, in the composition, the molar percentage (mol%) of the host material is 0 to 89%, the molar percentage of the TADF material is 10% to 99%, and the molar percentage of the triplet exciton releaser is 1% to 70%.

[0058] In some embodiments of this application, the composition comprises a TADF material and a triplet exciton releaser; wherein, based on molar percentages, the triplet exciton releaser has a molar percentage of 1% to 70%, and the TADF material has a molar percentage of 30% to 99%. It is understood that the molar percentage of the triplet exciton releaser can be arbitrarily selected from 1% to 70%, for example, 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; correspondingly, the molar percentage of the TADF material can be arbitrarily selected from 30% to 99%, for example, 99%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, etc. In this embodiment, the composition mainly consists of TADF material and a triplet exciton releaser. If the molar percentage of the triplet exciton releaser is too high, it will have a significant impact on the luminous efficiency. In this embodiment, the molar percentage of the triplet exciton releaser is controlled within 1% to 70%, comprehensively considering both luminous efficiency and lifetime. In other embodiments of this application, the composition consists of TADF material and a triplet exciton releaser; wherein, based on molar percentage, the molar percentage of the triplet exciton releaser is 10% to 50%, and the molar percentage of the TADF material is 50% to 90%. In other embodiments of this application, the composition consists of TADF material and a triplet exciton releaser; wherein, based on molar percentage, the molar percentage of the triplet exciton releaser is 30% to 50%, and the molar percentage of the TADF material is 50% to 70%.

[0059] In some embodiments of this application, the composition comprises a host material, a TADF material, and a triplet exciton releaser; wherein, in molar percentage, the host material comprises 20% to 89%, the TADF material comprises 10% to 30%, and the triplet exciton releaser comprises 1% to 50%. It is understood that the molar percentage of the host material can be arbitrarily selected from 20% to 89%, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 89%, etc.; the molar percentage of the TADF material can be arbitrarily selected from 10% to 30%, for example, 10%, 20%, 30%, etc.; and the molar percentage of the triplet exciton releaser can be arbitrarily selected from 1% to 50%, for example, 1%, 10%, 20%, 30%, 40%, 50%, etc. In this embodiment, the TADF material is diluted by the host material. When the molar percentage of the TADF material exceeds 30%, the device efficiency often decreases, and the efficiency roll-off becomes more severe. By controlling the molar percentage of the TADF material below 30%, the device efficiency can be guaranteed. By keeping the molar percentage of the TADF material above 10%, the energy transfer process from the host material to the TADF material can be sufficiently complete, ensuring that the TADF emits light fully. In other embodiments of this application, the composition consists of a host material, a TADF material, and a triplet exciton releaser; wherein, by molar percentage, the molar percentage of the host material is 30% to 75%, the molar percentage of the TADF material is 20%, and the molar percentage of the triplet exciton releaser is 5% to 50%. In other embodiments of this application, the composition consists of a host material, a TADF material, and a triplet exciton releaser; wherein, by molar percentage, the molar percentage of the host material is 70% to 75%, the molar percentage of the TADF material is 20%, and the molar percentage of the triplet exciton releaser is 5% to 10%.

[0060] In some embodiments of this application, the molar ratio of the TADF material to the triplet exciton releaser is (0.4-9):1. It is understood that the molar ratio of the TADF material to the triplet exciton releaser can take any value within the range of (0.4-9):1, for example, 0.4:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc. In some embodiments of this application, the molar ratio of the TADF material to the triplet exciton releaser is (2-4):1.

[0061] In some embodiments of this application, the composition comprises a host material, and the molar ratio of the TADF material to the triplet exciton releaser is (0.4-4):1. In some embodiments of this application, the composition does not comprise a host material, and the molar ratio of the TADF material to the triplet exciton releaser is (1-9):1.

[0062] In some embodiments of this application, the host material is mCBP, the TADF material is TMCz-BO, and the triplet exciton release agent is BSBCz.

[0063] In some embodiments of this application, the composition does not contain a host material, the TADF material is B-oCz, and the triplet exciton releaser is BSBCz.

[0064] Accordingly, this application also provides an ink comprising any of the compositions and solvents described above. The ink can be used to prepare the light-emitting layer of an organic light-emitting diode. It is understood that a suitable solvent can be selected based on the specific composition of the composition.

[0065] Please see Figure 2 The first embodiment of this application also provides an organic light-emitting diode, specifically an organic light-emitting diode (TADF-OLED) based on TADF light-emitting material, which includes an anode 100, a cathode 200 and a light-emitting layer 300, wherein the light-emitting layer 300 is disposed between the cathode 100 and the anode 200, and the light-emitting layer 300 comprises the composition described in any of the above embodiments.

[0066] It is understood that the organic light-emitting diode described in this application embodiment can be a positive structure, in which the anode 100 is disposed on the substrate; or it can be an inverted structure, in which the cathode 200 is disposed on the substrate. Regardless of whether it is a positive or inverted structure, a hole functional layer such as a hole transport layer, a hole injection layer, and / or an electron blocking layer can be disposed between the anode 100 and the light-emitting layer 300, and an electron functional layer such as an electron transport layer, an electron injection layer, and / or a hole blocking layer can be disposed between the cathode 200 and the light-emitting layer 300.

[0067] For example, please refer to Figure 3 , Figure 3 An organic light-emitting diode (OLED) according to a second embodiment of this application is shown. The OLED includes an anode 100, a hole injection layer 700, a hole transport layer 500, a light-emitting layer 300, an electron transport layer 400, an electron injection layer 600, and a cathode 200 stacked sequentially (from top to bottom or from bottom to top). The light-emitting layer 300 comprises the composition described in any of the above embodiments.

[0068] In some embodiments of this application, the thickness of the anode 100 is 30 nm to 70 nm. It is understood that the thickness of the anode 100 can be any value within the range of 30 nm to 70 nm, such as 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, etc.

[0069] In some embodiments of this application, the thickness of the cathode 200 is 60 nm to 140 nm. It is understood that the thickness of the cathode 200 can be any value within the range of 60 nm to 140 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, etc.

[0070] In some embodiments of this application, the thickness of the light-emitting layer 300 is 20 nm to 40 nm. It is understood that the thickness of the light-emitting layer 300 can be any value within the range of 20 nm to 40 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0071] In some embodiments of this application, the thickness of the hole transport layer 500 is 20 nm to 40 nm. It is understood that the thickness of the hole transport layer 500 can be any value within the range of 20 nm to 40 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0072] In some embodiments of this application, the thickness of the electron transport layer 400 is 20 nm to 40 nm. It is understood that the thickness of the electron transport layer 400 can be any value within the range of 20 nm to 40 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0073] All light-emitting diodes in the embodiments of this application can be prepared by the following methods.

[0074] Please see Figure 4 This application also provides a method for fabricating an inverted organic light-emitting diode, the method comprising the following steps:

[0075] S1, providing a cathode;

[0076] S2. A light-emitting layer is prepared on the cathode, the light-emitting layer comprising a TADF material and a triplet exciton releaser; wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material; and

[0077] S3. An anode is prepared on the light-emitting layer.

[0078] Please see Figure 5 The second embodiment of this application also provides a method for fabricating an organic light-emitting diode (OLED), wherein the OLED has a positive structure, and the fabrication method includes the following steps:

[0079] S1, providing the anode;

[0080] S2. A light-emitting layer is prepared on the anode, the light-emitting layer comprising a TADF material and a triplet exciton releaser; wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material; and

[0081] S3. Prepare a cathode on the light-emitting layer.

[0082] It is understood that, regardless of whether it is a positive or negative structure, the method for fabricating the organic light-emitting diode may further include: fabricating a hole injection layer, fabricating a hole transport layer, fabricating an electron injection layer, fabricating an electron transport layer, fabricating an electron blocking layer, and / or fabricating a hole blocking layer.

[0083] The material of the hole transport layer 500 can be, for example, TFB (poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine)), TAPC (4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline]), PVK (poly(9-vinylcarbazole)), TCTA (4,4',4″-tris(carbazole-9-yl)triphenylamine), CBP (4,4'-bis(9-carbazole)biphenyl), etc.

[0084] The material of the hole injection layer 600 can be, for example, PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)), m-MTDATA (4,4',4″-tris(N-3-methylphenyl-N-phenylamino)triphenylamine), 2-TNATA (4,4',4″-tris[2-naphthylphenylamino]triphenylamine), HAT-CN (2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene), F4-TCNQ (2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone), molybdenum trioxide (MoO3), etc.

[0085] The material of the electron transport layer 400 can be, for example, TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), TAZ (3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole), TmPyPb (1,3,5-tris[(3-pyridyl)-3-phenyl]benzene), BCP (2,9-dimethyl-4,7-biphenyl- 1,10-Phenanthroline), Bphen (4,7-diphenyl-1,10-phenanthroline), TmPyTz (2,4,6-tris(3-(pyridin-3-yl)phenyl)-1,3,5-triazine), B3PYMPM (4,6-bis(3,5-di(3-pyridinyl)phenyl)-2-methylpyrimidine), 3TPYMB (tris[2,4,6-trimethyl-3-(3-pyridinyl)phenyl]borane), etc.

[0086] The material of the electron injection layer 600 can be, for example, lithium fluoride (LiF), sodium fluoride (NaF), 8-hydroxyquinoline-lithium (Liq).

[0087] The various materials involved in the embodiments of this application above can be obtained through commercial purchases or synthesized using existing methods. In the above embodiments, the descriptions of each embodiment have different focuses; for parts not described in detail in a particular embodiment, please refer to the relevant descriptions in other embodiments.

[0088] The embodiments of this application will be described in detail below with reference to specific examples.

[0089] Example 1

[0090] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0091] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0092] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0093] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0094] S40. A solution-deposited luminescent layer of mCBP (75% molar percentage): TMCz-BO (20% molar percentage): BSBCz (5% molar percentage) is deposited on the hole transport layer with a thickness of 25 nm. The triplet exciton decay lifetime τ of TMCz-BO is... T The triplet exciton decay lifetime τ of BSBCz is approximately 0.75 μs. T Approximately 0.2 μs;

[0095] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0096] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0097] Example 2

[0098] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0099] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0100] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0101] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0102] S40. A solution-deposited luminescent layer of mCBP (70% molar percentage): TMCz-BO (20% molar percentage): BSBCz (10% molar percentage) is deposited on the hole transport layer with a thickness of 25 nm. The triplet exciton decay lifetime τ of TMCz-BO is... T The triplet exciton decay lifetime τ of BSBCz is approximately 0.75 μs. T Approximately 0.2 μs;

[0103] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0104] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0105] Example 3

[0106] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0107] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0108] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0109] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0110] S40. A solution-deposited luminescent layer of mCBP (60% molar percentage): TMCz-BO (20% molar percentage): BSBCz (20% molar percentage) is deposited on the hole transport layer as a luminescent layer with a thickness of 25 nm. The triplet exciton decay lifetime τ of TMCz-BO is... T The triplet exciton decay lifetime τ of BSBCz is approximately 0.75 μs. T Approximately 0.2 μs;

[0111] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0112] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0113] Example 4

[0114] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0115] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0116] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0117] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0118] S40. A solution-deposited 25nm thick layer of mCBP (30% molar percentage): TMCz-BO (20% molar percentage): BSBCz (50% molar percentage) is deposited on the hole transport layer. The layer consists of a luminescent layer and a triplet exciton decay lifetime τ of TMCz-BO. T The triplet exciton decay lifetime τ of BSBCz is approximately 0.75 μs. T Approximately 0.2 μs;

[0119] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0120] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0121] Example 5

[0122] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0123] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0124] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0125] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0126] S40. A solution-deposited 25nm thick B-oCz (90% molar percentage):BSBCz (10% molar percentage) layer is deposited on the hole transport layer. The layer consists of a B-oCz triplet exciton decay lifetime τ. T The triplet exciton decay lifetime τ of BSBCz is approximately 1.8 μs. T Approximately 0.2 μs;

[0127] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0128] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0129] Example 6

[0130] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0131] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0132] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0133] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0134] S40. A solution-deposited B-oCz (70% molar percentage):BSBCz (30% molar percentage) layer with a thickness of 25 nm was deposited on the hole transport layer. The triplet exciton decay lifetime τ of B-oCz was measured. T The triplet exciton decay lifetime τ of BSBCz is approximately 1.8 μs. T Approximately 0.2 μs;

[0135] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0136] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0137] Example 7

[0138] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0139] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0140] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0141] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0142] S40. A 25 nm thick B-oCz (50% molar percentage):BSBCz (50% molar percentage) emissive layer is deposited on the hole transport layer using a solution method. The triplet exciton decay lifetime τ of the B-oCz is... T The triplet exciton decay lifetime τ of BSBCz is approximately 1.8 μs. T Approximately 0.2 μs;

[0143] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0144] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0145] Comparative Example 1

[0146] This comparative example provides a TADF-OLED device, which is fabricated according to the following method:

[0147] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0148] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0149] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0150] S40. A solution-deposited mCBP (80% molar percentage): TMCz-BO (20% molar percentage) as the emitting layer with a thickness of 25 nm was deposited on the hole transport layer. The triplet exciton decay lifetime τ of TMCz-BO was also measured. TApproximately 0.75 μs;

[0151] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0152] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0153] Comparative Example 2

[0154] This embodiment provides a TADF-OLED device, which is fabricated according to the following method:

[0155] S10, using a transparent conductive thin film ITO as the anode, with a thickness of 50nm;

[0156] S20. PEDOT:PSS is deposited on ITO using a solution method as a hole injection layer with a thickness of 30 nm.

[0157] S30. TFB:PVK is deposited as a hole transport layer with a thickness of 25 nm on the hole injection layer using a solution method.

[0158] S40. A 25 nm thick B-oCz emissive layer is deposited on the hole transport layer using a solution method. The triplet exciton decay lifetime τ of the B-oCz is... T Approximately 1.8 μs;

[0159] S50. TPBi:Liq is deposited on the light-emitting layer as an electron transport layer using a vapor deposition method, with a thickness of 30nm.

[0160] S60. Al is deposited as a cathode on the electron transport layer using a vapor deposition method, with a thickness of 100 nm.

[0161] Figure 6 The current efficiency-luminance curves of the TADF-OLED devices prepared in Example 1, Example 2, and Comparative Example 1 are shown. Figure 6 It can be seen that the efficiency degradation of both Example 1 and Example 2 has been improved, with the efficiency improvement of Example 2 being more significant than that of Example 1. Figure 7 The lifetime curves (time T from initial brightness (not illuminance) to decay to 90%) of the TADF-OLED devices prepared in Examples 1, 2, and 1 are shown. 90 ),from Figure 7 It can be seen that the lifetime of both Example 1 and Example 2 is significantly improved, with the improvement in lifetime of Example 2 being more significant than that of Example 1. Therefore, the triplet exciton release agent used in the embodiments of this application can improve device efficiency degradation and increase device lifetime.

[0162] In summary, this application utilizes a triplet exciton release agent with a triplet exciton energy lower than that of TADF material, a singlet exciton energy higher than that of TADF material, and a triplet exciton decay lifetime lower than that of TADF material. This allows the release agent to capture triplet excitons generated by TADF material, enabling a portion of the triplet excitons generated in TADF to transfer to the release agent molecules and de-excite a portion of the triplet excitons at a faster rate. This rapid decay of triplet excitons effectively reduces the number of triplet excitons, thereby significantly reducing the annihilation process between triplet excitons and singlet excitons, as well as between triplet excitons and charge polarons. This improves the efficiency decay of organic light-emitting diodes (OLEDs) and increases their lifetime.

[0163] The above provides a detailed description of a composition for organic light-emitting diodes and its application provided by the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composition for use in organic light-emitting diodes, characterized in that, The composition comprises a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material. The triplet exciton releaser is selected from at least one of cyclooctatetraene, dinaphthalene, and 4,4'-bis[(N-carbazole)styryl]biphenyl; the TADF material is selected from at least one of TMCz-BO, v-DABNA, DMAC-TRZ, TBP-DMAc, 4CzFCN, t4CzIPN, and B-oCz. The molar ratio of the TADF material to the triplet exciton releaser is (1-9):

1.

2. The composition for an organic light-emitting diode as claimed in claim 1, characterized in that, The ratio of the triplet exciton decay lifetime of the triplet exciton releaser to the triplet exciton decay lifetime of the TADF material is 1:(3~9).

3. The composition for an organic light-emitting diode as described in claim 1, characterized in that, The triplet exciton releaser has a triplet exciton decay lifetime of less than or equal to 1 μs.

4. The composition for an organic light-emitting diode as claimed in claim 1, characterized in that, The composition further comprises, by molar percentage, a host material comprising 60 to 80% of the host material, a TADF material comprising 10% to 30% of the TADF material, and a triplet exciton releaser comprising 5% to 10% of the triplet exciton releaser.

5. The composition for an organic light-emitting diode as described in claim 4, characterized in that, The main material is selected from at least one of mCBP, CBP, PPF, CzSi, DCzPPY and DPEPO.

6. The composition for an organic light-emitting diode as claimed in claim 1, characterized in that, The composition comprises a TADF material and a triplet exciton releaser; wherein, by molar percentage, the triplet exciton releaser is 10% to 50%, and the TADF material is 50% to 90%; or, The composition comprises a host material, a TADF material, and a triplet exciton releaser; wherein, by molar percentage, the host material is 70% to 75%, the TADF material is 20%, and the triplet exciton releaser is 5% to 10%.

7. An ink, characterized in that, It comprises the composition and solvent for organic light-emitting diodes as described in any one of claims 1 to 6.

8. An organic light-emitting diode, characterized in that, It includes a cathode, an anode, and a light-emitting layer, the light-emitting layer being disposed between the cathode and the anode, and the light-emitting layer comprising the composition for an organic light-emitting diode as described in any one of claims 1 to 6.

9. A method for fabricating an organic light-emitting diode, characterized in that, Includes the following steps: Provide cathode; A light-emitting layer is fabricated on the cathode. The light-emitting layer comprises a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material. An anode is prepared on the light-emitting layer; Alternatively, provide an anode; A light-emitting layer is prepared on the anode, the light-emitting layer comprising a TADF material and a triplet exciton releaser, wherein the triplet exciton energy of the triplet exciton releaser is lower than the triplet exciton energy of the TADF material, the singlet exciton energy of the triplet exciton releaser is greater than the singlet exciton energy of the TADF material, and the triplet exciton decay lifetime of the triplet exciton releaser is less than the triplet exciton decay lifetime of the TADF material; and A cathode is fabricated on the light-emitting layer; The triplet exciton releaser is selected from at least one of cyclooctatetraene, dinaphthalene, and 4,4'-bis[(N-carbazole)styryl]biphenyl; the TADF material is selected from at least one of TMCz-BO, v-DABNA, DMAC-TRZ, TBP-DMAc, 4CzFCN, t4CzIPN, and B-oCz. The molar ratio of the TADF material to the triplet exciton releaser is (1-9):1.

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