Luminescent composition and organic electroluminescent device

Abstract

The present application belongs to the field of organic optoelectronic materials and devices, and discloses a luminescent composition and an organic electroluminescent device, which are composed of a first compound, a second compound, and a third compound; in terms of mass percentage, the mass percentage of the first compound is 0.1 to 20.0%, the mass percentage of the second compound is 5.0 to 60.0%, and the mass percentage of the third compound is 20.0 to 94.9%; the molecular structure of the first compound is shown in formula (1). In the luminescent composition of the present application, a compound shown in formula (1) is used as the first compound, and the first compound has a luminescent spectrum characteristic of narrow half-peak width. By efficiently transferring the exciton energy in the second compound to the first compound in the form of #imgabs0# energy transfer, the second compound sensitizes the first compound to emit light, significantly reducing the half-peak width of the device spectrum, thereby achieving device performance with high luminous efficiency and high color purity.

Description

Technical Field

[0001] The present application belongs to the technical field of organic optoelectronic materials and devices, and specifically relates to a luminescent composition and an organic electroluminescent device. Background Art

[0002] Compared to traditional display technologies, organic light-emitting diodes (OLEDs) offer advantages such as high brightness and low power consumption. In small-size displays, they offer high contrast, wide viewing angles, full color, and a wide operating temperature range. They are gradually entering the consumer electronics market and are widely used in smartphones, wearable devices, and automotive displays. The development of high-performance and stable OLEDs is crucial for addressing bottlenecks in the OLED display industry and promoting its industrialization.

[0003] Fundamental to developing high-performance and stable organic electroluminescent devices is the research and exploration of the light-emitting layer. This requires not only the properties of the light-emitting material itself, but also in-depth exploration of the structure and composition of the light-emitting layer within the device to enhance all aspects of device performance. Currently, red and green phosphorescent materials composed of coordinated metals such as iridium and platinum have reached industrial standards in terms of efficiency and lifespan. However, devices using blue-emitting materials suffer from large efficiency roll-off, wide spectrum, and insufficient stability. Therefore, the development of high-performance and stable blue-emitting materials is a major technical challenge that the industry needs to overcome.

[0004] For blue fluorescent materials or blue TADF (thermally activated delayed fluorescence) materials paired with a single host material, although the devices of the blue fluorescent system have a good lifespan, the luminous efficiency is still low (external quantum efficiency <10%). For the blue TADF material system, due to its long exciton lifetime and narrow recombination area of ​​the light-emitting layer, it is easy for excitons and polarons to annihilate inside the device, resulting in non-radiative energy loss and severe device efficiency roll-off. On the other hand, the spectrum of blue TADF materials is relatively wide, which can easily cause a significant decrease in the color purity of blue light. Therefore, there is an urgent need for a new blue light composition solution with high luminous efficiency, low efficiency roll-off, and a narrow emission spectrum. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present application provides a luminescent composition and an organic electroluminescent device. This luminescent composition is a luminescent composition containing a blue dopant (BD), which can improve the problems of existing blue light devices such as large efficiency roll-off, short life and insufficient color purity.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] A luminescent composition, wherein the composition is composed of a first compound, a second compound and a third compound, and is a ternary luminescent composition containing indolecarbazole;

[0008] Wherein, in terms of mass percentage, the mass percentage of the first compound is 0.1-20.0%, the mass percentage of the second compound is 5.0-60.0%, and the mass percentage of the third compound is 20.0-94.9%;

[0009] The molecular structure of the first compound is shown in formula (1):

[0010]

[0011] wherein Ring A is a substituted or unsubstituted fused aryl ring having 10 to 50 ring carbon atoms, or a substituted or unsubstituted fused heterocyclic ring having 8 to 50 ring atoms;

[0012] R1 to R4 are each independently selected from a hydrogen atom, a deuterium atom, a tritium atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, an amino group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted fluoroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 20 carbon atoms, a substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, -N(R 101 )(R 102 ), a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 50 ring atoms; R1 to R4 are not bonded to each other or are bonded to form a further ring structure; n is an integer selected from 0 to 4;

[0013] X3~X 16 Each independently represents a nitrogen atom or a carbon atom, X3 to X 16 Contains at least one nitrogen atom; X m With X m+1 They are not bonded to each other or bonded to further form a ring structure, and m is selected from 3, 4, 6 to 8, 10, 11, 13 to 15;

[0014] Ar1, Ar2, R 101 、R 102Each of them is independently a hydrogen atom, a deuterium atom, a tritium atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 50 ring atoms.

[0015] In the luminescent composition of the present application, the first compound is used as a guest material, the second compound is used as an auxiliary host material, and the third compound is used as a host material. In the luminescent composition of the present application, the compound shown in formula (1) is used as the first compound, the first compound is a compound containing indolecarbazole, and the first compound has a luminescent spectrum characteristic of narrow half-peak width. By increasing the exciton energy in the second compound to The energy is efficiently transferred to the first compound, so that the second compound sensitizes the first compound to emit light, which significantly reduces the half-peak width of the device's spectrum, thereby achieving device performance with high luminous efficiency and high color purity.

[0016] The second compound may be a thermally activated delayed fluorescent material, and the third compound may be a fluorescent material. When the first compound is a compound containing indolecarbazole, the second compound is a thermally activated delayed fluorescent material, and the third compound is a fluorescent material, the first compound has a luminescence spectrum characteristic of narrow half-peak width, and the exciton energy in the second compound is converted to The energy is efficiently transferred to the first compound, so that the second compound sensitizes the first compound to emit light, which significantly reduces the half-peak width of the device's spectrum, thereby achieving device performance with high luminous efficiency and high color purity.

[0017] In one or more embodiments, the first compound shown in formula (1) is preferably a structure as shown in any one of the following formulas (3-1) to (3-15). When the first compound adopts the structure shown in any one of formulas (3-1) to (3-15), the nitrogen-containing indole and carbazole molecule has a rigid skeleton structure, which can reduce the degree of relaxation of the excited state structure and achieve a narrower spectral half-width. In addition, the insertion of a substituent unit at the periphery of the indole and carbazole can increase the molecular distance between the first compound and the second compound, avoid the triplet exciton of the second compound from being quenched by the first compound through Dexter energy transfer, and is beneficial to improving the luminous efficiency of the device.

[0018]

[0019] In formulae (3-1) to (3-15), R1 to R4, Ar1, and Ar2 are the same as defined in formula (1), and n is an integer selected from 0 to 2.

[0020] In one or more embodiments, the first compound represented by formula (1) is preferably selected from the following compounds of formulas (5-1) to (5-75), but is not limited to the following compounds:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] It should be noted that the first compound can be prepared according to conventional chemical synthesis methods in the art, and the steps and conditions thereof can refer to the steps and conditions of similar reactions in the art.

[0028] In one or more embodiments, the luminescent composition of the present application comprises a first compound represented by formula (1) as a luminescent guest material, and a composite system composed of a second compound and a third compound constitutes a luminescent host material. In the luminescent composition of the present application, the mass percentage of the first compound is preferably 0.1 to 20.0%, the mass percentage of the second compound is preferably 5.0 to 60%, and the mass percentage of the third compound is preferably 20 to 94.9%.

[0029] In one or more embodiments, the light-emitting composition of the present application comprises a first compound as a light-emitting guest material, and a second compound and a third compound, each with varying mass percentages, constitute a light-emitting host material. That is, in the light-emitting composition of the present application, the mass percentage of the first compound is a fixed value, the mass percentage of the second compound varies in at least two ways, and the mass percentage of the third compound varies with the mass percentage of the second compound. When using this light-emitting composition to prepare a light-emitting layer, preferably, the mass percentage of the second compound on one side of the light-emitting layer is higher than the mass percentage of the second compound on the other side of the light-emitting layer. When a device is fabricated, one side of the light-emitting layer is the side closest to the anode layer, and the other side of the light-emitting layer is the side closest to the cathode layer.

[0030] Furthermore, in the luminescent composition of the present application, the first compound serves as a luminescent guest material, and the mass percentage of the second compound changes linearly with a constant rate of change, and together with the third compound, constitutes a luminescent host material. That is, in the luminescent composition of the present application, the mass percentage of the first compound is a fixed value, the mass percentage of the second compound changes linearly with a constant rate of change for doping, and the mass percentage of the third compound changes with the mass percentage of the second compound. In the process of preparing a luminescent layer using this luminescent composition, the rate of co-evaporation of the second compound can be reduced so that the mass percentage of the doped compound decreases linearly with a constant rate of change, and the rate of change can range from 0.125% / nm to 4% / nm. Furthermore, in the luminescent composition, the difference between the highest mass percentage of the second compound and the lowest mass percentage of the second compound is 5.0 to 20.0%. For example, the mass percentage of the second compound changes linearly at a constant rate of change, the thickness of the light-emitting layer is 30 nm, the mass percentage of the second compound on one side of the light-emitting layer is 40%, and then decreases linearly at a rate of change of 0.667% / nm toward the other side of the light-emitting layer until the mass percentage of the second compound on the other side of the light-emitting layer is 20%, completing the preparation of the light-emitting layer. The difference between the highest mass percentage of the second compound (40%) and the lowest mass percentage of the second compound (20%) is 20.0%.

[0031] In one or more embodiments, the singlet energy level of the first compound is less than or equal to the singlet energy level of the second compound, and the triplet energy level of the third compound is higher than the triplet energy level of the second compound, so that the second compound can be Energy is transferred to the first compound.

[0032] In one or more embodiments, the second compound of the present application is selected from at least one of a compound containing diarylsulfone and its derivatives, a compound containing benzonitrile and its derivatives, a compound containing triazine and its derivatives, a compound containing pyrimidine and its derivatives, and a compound containing benzophenone and its derivatives. Such a compound has a singlet energy level higher than or equal to the singlet energy level of the first compound, but a triplet energy level lower than the triplet energy level of the third compound.

[0033] In one or more embodiments, the second compound is preferably selected from the compounds represented by the following formulas (7-1) to (7-102), but is not limited to the following compounds. These preferred compounds meet the above requirements for the second compound and are relatively easy to synthesize or obtain.

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] In one or more embodiments, the third compound is selected from at least one of a compound containing imidazole and its derivatives, a compound containing fluorene and its derivatives, a compound containing triazine and its derivatives, a compound containing a silicon group, a compound containing carbazole and its derivatives, a compound containing a nitrogen heterocycle and its derivatives, or a compound containing pyrimidine and its derivatives. The triplet energy level of such a compound is higher than the triplet energy level of the second compound used in the present application, thereby preventing electron transfer from the second compound to the third compound used through Dexter reaction.

[0042] In one or more embodiments, the third compound is preferably selected from the following compounds represented by formula (9-1) to formula (9-99), but is not limited to the following compounds. These preferred compounds meet the above requirements for the third compound and are relatively easy to synthesize or obtain.

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049] The present application also provides an organic electroluminescent device, comprising a substrate and an anode layer, an organic light-emitting functional layer, and a cathode layer sequentially formed on the substrate, wherein the organic light-emitting functional layer includes a light-emitting layer, wherein the light-emitting layer uses the above-mentioned light-emitting composition. The light-emitting composition provided in the present application can be used not only in organic electroluminescent devices, but also in products such as organic optical sensors, solar cells, lighting elements, organic thin-film transistors, organic field-effect transistors, organic thin-film solar cells, information tags, or electronic paper.

[0050] Furthermore, the organic light-emitting functional layer further includes any one or a combination of multiple of a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer.

[0051] Preferably, the organic light-emitting functional layer includes a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer. The hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer and the electron injection layer are sequentially formed on the anode layer of the substrate, and the light-emitting layer is located between the hole transport layer and the electron transport layer. Furthermore, the mass percentage of the second compound on one side of the light-emitting layer is higher than the mass percentage of the second compound on the other side of the light-emitting layer, that is, the mass percentage of the second compound on the side close to the hole transport layer is higher than the mass percentage on the side close to the electron transport layer. Since the hole mobility of the second compound is higher than the electron mobility, the concentration of the second compound on the side of the hole transport layer is higher than that on the side of the electron transport layer mainly to broaden the recombination area of ​​the carriers and reduce the exciton concentration of the light-emitting layer, thereby reducing the concentration quenching and efficiency roll-off of the light-emitting layer, and ultimately improving the luminous efficiency of the device.

[0052] Next, the anode layer, cathode layer, hole injection layer, hole transport layer, electron transport layer and electron injection layer in the organic electroluminescent device of the present application are further described.

[0053] In the organic electroluminescent device of the present application, the anode layer and / or cathode layer are light-transmissive. The organic electroluminescent device needs to emit light from at least one side, so the electrode plate on the light-emitting side needs to be transparent. Generally, since only one side needs to emit light, the anode layer or cathode layer is set to be transparent.

[0054] In the organic electroluminescent device of the present application, the main function of the anode layer is to inject holes into the hole injection layer, the hole transport layer or the light-emitting layer, and preferably uses an anode layer material with a work function of 4.5 eV or more. In one or more embodiments, the anode layer material is preferably selected from one of indium tin oxide alloy (ITO), tin oxide (NESA), indium gallium zinc oxide (IGZO), silver, etc. The anode layer can be formed into an anode layer thin film by thermal evaporation, sputtering, etc. Preferably, the light transmittance of the visible area of ​​the anode layer is greater than 80%. In addition, the square resistance of the anode layer is preferably 500Ω / cm -1 Hereinafter, the film thickness is preferably selected within the range of 10 to 200 nm.

[0055] In the organic electroluminescent device of the present application, the main function of the cathode layer is to inject electrons into the electron injection layer, electron transport layer or light-emitting layer, and preferably a material with a small work function is used. The cathode layer material is not particularly limited, and is preferably selected from one of aluminum, magnesium, silver, magnesium-silver alloy, magnesium-aluminum alloy, aluminum-lithium alloy, etc. Similarly, the cathode layer can also be formed into a cathode layer thin film by thermal evaporation, sputtering, etc., and the film thickness of the cathode layer is preferably selected in the range of 10 to 200 nm. In addition, light can also be extracted from the cathode side as needed.

[0056] In the organic electroluminescent device of the present application, the light-emitting layer is a light-emitting composition layer of the present application, which is a light-emitting composition containing indolecarbazole and is composed of a composite host system composed of a first compound doped with a second compound and a third compound. The thickness of the light-emitting layer is preferably 5 nm to 40 nm.

[0057] In the organic electroluminescent device of the present application, the thickness of the electron transport layer is preferably 10 nm to 50 nm, and the thickness of the hole transport layer is preferably 20 nm to 200 nm.

[0058] In the organic electroluminescent device of the present application, the electron transport layer is an organic layer formed between the light-emitting layer and the cathode layer, and its main function is to transport electrons from the cathode to the light-emitting layer. As an electron transport material for the electron transport layer, an aromatic heterocyclic compound containing one or more heteroatoms in the molecule is preferably used, and a nitrogen-containing ring derivative is particularly preferably used. In addition, the nitrogen-containing ring derivative is preferably an aromatic ring having a nitrogen-containing six-membered ring or five-membered ring skeleton, or a fused aromatic ring compound having a nitrogen-containing six-membered ring or five-membered ring skeleton.

[0059] In the organic electroluminescent device of the present application, the electron transport material is preferably selected from the following compounds but is not limited to the following compounds:

[0060]

[0061]

[0062] In the organic electroluminescent device of the present application, the hole transport layer is an organic layer formed between the light-emitting layer and the anode layer (or hole injection layer). Its primary function is to transport holes from the anode layer to the light-emitting layer. As the hole transport material for the hole transport layer, an aromatic amine compound is preferably used, such as an aromatic amine derivative represented by the following formula (70).

[0063]

[0064] In the above formula (70), Ar1 to Ar4 represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 50 ring carbon atoms (preferably 6 to 30, more preferably 6 to 20, and further preferably 6 to 12), a fused aromatic hydrocarbon group having 6 to 50 ring carbon atoms (preferably 6 to 30, more preferably 6 to 20, and further preferably 6 to 12) which may have a substituent, a substituted or unsubstituted aromatic heterocyclic group having 5 to 50 ring atoms (preferably 5 to 30, more preferably 5 to 20, and further preferably 5 to 12), a substituted or unsubstituted fused aromatic heterocyclic group having 5 to 50 ring atoms (preferably 5 to 30, more preferably 5 to 20, and further preferably 5 to 12), or a group in which the aforementioned aromatic hydrocarbon group or the aforementioned fused aromatic hydrocarbon group is bonded to the aforementioned aromatic heterocyclic group or the aforementioned fused aromatic heterocyclic group.

[0065] In the above formula (70), a ring may be formed between Ar1 and Ar2, and a ring may be formed between Ar3 and Ar4. In the above formula (70), L represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 50 ring carbon atoms (preferably 6 to 30, more preferably 6 to 20, and even more preferably 6 to 12), a fused aromatic hydrocarbon group having 6 to 50 ring carbon atoms (preferably 6 to 30, more preferably 6 to 20, and even more preferably 6 to 12) which may have a substituent, a substituted or unsubstituted aromatic heterocyclic group having 5 to 50 ring atoms (preferably 5 to 30, more preferably 5 to 20, and even more preferably 5 to 12), or a substituted or unsubstituted fused aromatic heterocyclic group having 5 to 50 ring atoms (preferably 5 to 30, more preferably 5 to 20, and even more preferably 5 to 12).

[0066] In the organic electroluminescent device of the present application, another aromatic amine compound, such as an aromatic amine derivative represented by the following formula (71), may also be preferably used as a hole transport material for the hole transport layer.

[0067]

[0068] In the above formula (71), the definitions of Ar1 to Ar3 are the same as those of Ar1 to Ar4 in formula (70).

[0069] In the organic electroluminescent device of the present application, the hole transport material is preferably selected from the following compounds but is not limited to the following compounds:

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] In addition, it is preferred to dope an n-type dopant into the electron transport layer and a p-type dopant into the hole transport layer. The main functions of the n-type dopant and the p-type dopant are to enhance the transport properties of the electron transport layer and the hole transport layer, respectively, and to reduce the driving voltage of the organic electroluminescent device. In one or more embodiments, the n-type dopant may be preferably one of Li, Cs, Ba, Yb, CsF, BaO, Liq, Naq, Libpp, Bepq2, Bepp2, LiF, CsCO3, ZnO, etc.; in one or more embodiments, the p-type dopant may be preferably one of HATCN, F4TCNQ, HI-3, etc. When the hole transport layer contains a p-type dopant and a hole transport material, the doping concentration of the p-type dopant is preferably 0.1% to 50.0% by mass; when the electron transport layer contains the n-type dopant and the electron transport material, the doping concentration of the n-type dopant is preferably 1.0% to 90.0% by mass.

[0078] Among them, the structural formulas of n-type dopant materials Liq, Naq, Libpp, Bepq2, and Bepp2 are as follows:

[0079]

[0080]

[0081] In the organic electroluminescent device of the present application, the hole injection layer preferably has a thickness of 1 nm to 50 nm, and the electron injection layer preferably has a thickness of 0.1 nm to 15 nm.

[0082] In the organic electroluminescent device of the present application, it is preferred to have an electron injection layer in the interface region between the cathode layer and the electron transport layer (or light-emitting layer). The main function of the electron injection layer is to promote the injection of electrons from the cathode layer to the electron transport layer or the light-emitting layer, thereby improving the luminous brightness and device life of the organic electroluminescent device. Here, the electron injection material refers to a material with a work function of 3.8 eV or less. As a specific example, it can be preferably selected from Li, Cs, Ba, Yb, LiF, CsF, BaO, etc. The electron injection layer can be formed into an electron injection layer thin film by thermal evaporation, and the evaporation rate is preferably 200 nm. The thickness of the film thus produced is preferably selected within the range of 0.1 to 15 nm.

[0083] In the organic electroluminescent device of the present application, a hole injection layer is preferably provided at the interface region between the anode layer and the hole transport layer (or light-emitting layer). The main function of the hole injection layer is to promote the injection of holes from the anode layer into the hole transport layer or the light-emitting layer, thereby reducing the driving voltage of the organic electroluminescent device and improving the luminous brightness and device life. Here, the hole injection material refers to an acceptor-type organic material containing a deep LUMO energy level, and as a specific example thereof, it can be preferably selected from one of HATCN, F4TCNQ, HI-3, etc.

[0084] Among them, the structural formulas of the hole injection layer materials HATCN, F4-TCNQ, and HI-3 are as follows:

[0085]

[0086]

[0087] The organic electroluminescent device provided in this application is a device containing a ternary light-emitting composition prepared by gradient doping of a second compound. Compared with conventional organic electroluminescent devices in the prior art, it has the following advantages:

[0088] 1) Using a compound as shown in formula (1) as the first compound, the first compound has a luminescence spectrum characteristic of narrow half-peak width, and the exciton energy in the second compound is The energy is efficiently transferred to the first compound, so that the second compound sensitizes the first compound to emit light, which significantly reduces the half-peak width of the device's spectrum, thereby achieving device performance with high luminous efficiency and high color purity.

[0089] 2) The second compound is doped in a gradient doping manner, which can improve the carrier balance in the light-emitting layer, effectively widen the recombination area of ​​the light-emitting layer, reduce the exciton concentration, reduce the annihilation of excitons and polarons inside the device, and suppress the efficiency roll-off of the device.

[0090] 3) The nitrogen-containing indolocarbazole molecule possesses a rigid backbone structure, which reduces the degree of structural relaxation in the excited state and achieves a narrower spectral half-width. Furthermore, the incorporation of substituent units into the periphery of the indolocarbazole increases the molecular distance between the first and second compounds, preventing quenching of triplet excitons in the second compound by the first compound via Dexter energy transfer, thereby improving the luminescence efficiency of the device.

[0091] 4) The luminescent composition of the present application is a ternary luminescent composition. Compared with the binary luminescent composition consisting of only the second compound and the third compound, the second compound can transfer the exciton energy to The energy is efficiently transferred to the first compound to realize luminescence, and the first compound has a narrow luminescence spectrum characteristic, which gives it the advantage of high color purity; compared with the binary luminescent composition consisting of only the first compound and the third compound, the second compound, as an auxiliary host, can utilize triplet excitons through reverse intersystem crossing, thereby improving the luminescence efficiency of the ternary luminescent composition, giving it the advantage of high-efficiency luminescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 Schematic diagram of the structure of the organic electroluminescent device used in Examples 1 to 11 and Comparative Examples 1 to 3.

[0093] Explanation of reference numerals: 11, cathode layer; 12, electron injection layer; 13, second electron transport layer; 14, first electron transport layer; 15, light-emitting layer; 16, second hole transport layer; 17, first hole transport layer; 18, hole injection layer; 19, anode layer. DETAILED DESCRIPTION

[0094] The present application provides a light-emitting composition and an organic electroluminescent device. To make the purpose, technical solution, and effects of the present application clearer and more explicit, the present application is further described below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0095] The present application is further described below through specific examples.

[0096] Synthesis and preparation of compound 5-5:

[0097]

[0098] Under a nitrogen atmosphere, P-2 (2.1 g, 7.1 mmol, 1 eq), sodium hydride (NaH, 0.33 g, 14 mmol, 2 eq) and 3-fluoro-4-bromopyridine (2.7 g, 15 mmol, 2.2 eq) were dispersed in 30 mL of N, N-dimethylformamide (DMF) and reacted at 60 ° C for 12 hours. After the reaction, a large amount of water was added, extracted with dichloromethane, the organic layer was collected, and dried over anhydrous magnesium sulfate. The crude product was further purified by column chromatography using petroleum ether: dichloromethane (90:10, v:v). The intermediate product P-4 was obtained with a yield of 3.1 g (70%).

[0099] Under a nitrogen atmosphere, a mixture of intermediate product P-4 (3.0 g, 4.9 mmol, 1 eq), palladium (II) acetate [Pd(OAc)2] (11 mg, 49 umol, 0.01 eq), tri-tert-butylphosphine (20 mg, 0.10 mmol, 0.02 eq) and sodium tert-butoxide (1.1 g, 11 mmol, 2.2 eq) was dispersed in 30 mL of N,N-dimethylacetamide (DMAC) and reacted at 140 ° C for 12 hours. After the reaction, a large amount of water was added, extracted with dichloromethane, and the organic layer was collected and dried over anhydrous magnesium sulfate. The crude product was purified by column chromatography using petroleum ether: dichloromethane (90:10, v:v) as eluent. Product 5-5 was obtained with a yield of 1.6 g (74%).

[0100] Synthesis of compound 5-12:

[0101]

[0102] Under a nitrogen atmosphere, 8,8-dimethyl-5,8-dihydroindeno[2,1-c]carbazole (2 g, 7.06 mmol, 1 eq), sodium hydride (NaH, 0.33 g, 14.12 mmol, 2 eq) and 1,5-dibromo-2,4-difluoronaphthalene (1 g, 2.06 mmol, 0.52 eq) were dispersed in 20 mL of N,N-dimethylformamide (DMF) and reacted at 60 ° C for 12 hours. After the reaction, a large amount of water was added, extracted with dichloromethane, and the organic layer was collected and dried over anhydrous magnesium sulfate. The crude product was further purified by column chromatography using petroleum ether: dichloromethane (volume ratio 90:10). The intermediate product P-8 was obtained with a yield of 1.8 g (86.4%).

[0103] Under a nitrogen atmosphere, a mixture of intermediate product P-8 (1 g, 1.25 mmol, 1 eq), palladium (II) acetate [Pd(OAc)2] (0.14 g, 0.63 mmol, 0.5 eq), triphenylphosphine (PPh3, 0.21 g, 0.75 mmol, 0.6 eq), benzyltriethylammonium chloride (BnEt3NCl, 0.57 g, 2.5 mmol, 2 eq) and potassium carbonate (K2CO3, 1.73 g, 10 mmol, 8 eq) was dispersed in 20 mL of N,N-dimethylacetamide (DMAc) and reacted at 160°C for 6 hours. After the reaction, a large amount of water was added, and the mixture was extracted with dichloromethane. The organic layer was collected and dried over anhydrous magnesium sulfate. The crude product was purified by column chromatography using petroleum ether:dichloromethane (90:10, v:v) as eluent. Compound 5-12 was obtained as a white solid with a yield of 0.26 g (12.5%).

[0104] Synthesis of compound 5-41:

[0105]

[0106] Under a nitrogen atmosphere, P-10 (2 g, 7.06 mmol, 1 eq), sodium hydride (NaH, 0.33 g, 14.12 mmol, 2 eq) and 1,5-dibromo-2,4-difluoronaphthalene (1 g, 2.06 mmol, 0.52 eq) were dispersed in 20 mL of N,N-dimethylformamide (DMF) and reacted at 60 ° C for 12 hours. After the reaction, a large amount of water was added, extracted with dichloromethane, the organic layer was collected, and dried over anhydrous magnesium sulfate. The crude product was further purified by column chromatography using petroleum ether: dichloromethane (volume ratio 90:10). The intermediate product P-12 was obtained with a yield of 1.5 g (72.0%).

[0107] Under a nitrogen atmosphere, a mixture of intermediate product P-12 (1 g, 1.25 mmol, 1 eq), palladium(II) acetate [Pd(OAc)2] (0.14 g, 0.63 mmol, 0.5 eq), triphenylphosphine (PPh3, 0.21 g, 0.75 mmol, 0.6 eq), benzyltriethylammonium chloride (BnEt3NCl, 0.57 g, 2.5 mmol, 2 eq), and potassium carbonate (K2CO3, 1.73 g, 10 mmol, 8 eq) was dispersed in 20 mL of N,N-dimethylacetamide (DMAc) and reacted at 160°C for 6 hours. After the reaction, a large amount of water was added, and the mixture was extracted with dichloromethane. The organic layer was collected and dried over anhydrous magnesium sulfate. The crude product was purified by column chromatography using petroleum ether:dichloromethane (90:10, v:v) as eluent. Compound 5-41 was obtained as a white solid with a yield of 0.30 g (14.4%).

[0108] Examples 1 to 8

[0109] like Figure 1 As shown, a 30 mm × 30 mm × 0.7 mm thick glass substrate with an anode layer 19 (the anode layer is a 95 nm thick ITO transparent electrode) was ultrasonically cleaned in acetone (once), a cleaning solution (once), ultrapure water (three times), and isopropyl alcohol (once), with each ultrasonic cleaning step lasting 10 minutes. The cleaned glass substrate with the anode layer 19 was then placed in an oven at 80°C for 3 hours. The cleaning solution is a commercially available product, formulated with solid salts and nonionic surfactants such as polyoxyethylene ether, and is used to clean ITO glass. It is used to remove dirt and oil from the surface of glass substrates with ITO transparent electrodes.

[0110] The baked ITO glass substrate with the anode layer 19 was subjected to vacuum plasma cleaning for 10 minutes.

[0111] The plasma-treated glass substrate with the anode layer 19 was mounted on a substrate holder of a vacuum deposition apparatus. First, the compound HATCN was deposited on the surface where the transparent electrode lines were formed to cover the transparent electrode, thereby forming a hole injection layer 18 with a thickness of 10 nm.

[0112] Compound HT-10 was vapor-deposited on the hole injection layer 18 to form a first hole transport layer 17 having a film thickness of 60 nm.

[0113] Compound HT-45 was evaporated on the first hole transport layer 17 to form a second hole transport layer 16 having a thickness of 10 nm.

[0114] Next, a second compound (auxiliary host material), a third compound (host material), and a first compound (guest material) were co-evaporated onto the second hole-transporting layer 16 to form a 30 nm thick light-emitting layer 15. The mass concentration of the first compound in the light-emitting layer 15 was set to 1%, the mass concentration of the second compound was set to 30%, and the mass concentration of the third compound was set to 69%.

[0115] In Examples 1 to 8, the mass concentrations of the first compound, the second compound, and the third compound of each example are shown in Table 1 below.

[0116] Table 1

[0117] Example First compound (1%) Second compound (30%) The third compound (69%) 1 5-5 7-1 9-47 2 5-5 7-4 9-47 3 5-5 7-19 9-47 4 5-5 7-84 9-47 Example First compound (1%) Second compound (30%) The third compound (69%) 5 5-12 7-84 9-47 6 5-41 7-84 9-47 Example First compound (1%) Second compound (30%) The third compound (69%) 7 5-5 7-84 9-40 8 5-5 7-84 9-45

[0118] Next, compound ET-15 was evaporated to form a first electron transport layer 14 having a thickness of 10 nm.

[0119] Liq and ET-1 were co-evaporated on the first electron transport layer 14 , with the mass concentration of Liq being 50% and the balance being ET-1, to form a second electron transport layer 13 with a film thickness of 20 nm.

[0120] Furthermore, Liq was vapor-deposited on the second electron transport layer 13 to form the electron injection layer 12 having a film thickness of 2 nm.

[0121] Then, metal Al was vapor-deposited on the electron injection layer 12 to form the cathode layer 11 having a film thickness of 100 nm.

[0122] Examples 9 to 12

[0123] The light-emitting layer of the organic electroluminescent device prepared in Examples 9 to 12 is formed by doping the second compound with a gradient concentration on the second hole transport layer (the composition is shown in Table 2 below), wherein the mass percentage of the second compound on the side close to the hole transport layer is higher than the mass percentage on the side close to the electron transport layer. The mass percentage of the second compound on the side close to the hole transport layer is 40%, and the mass percentage decreases at a constant rate of change of 0.667% / nm. The mass percentage of the second compound on the side close to the electron transport layer is 20%. In addition, the structure and preparation method of the remaining layers are the same as those of Examples 1 to 8.

[0124] Table 2

[0125]

[0126]

[0127] Comparative Examples 1 to 3

[0128] The organic electroluminescent devices prepared in Comparative Examples 1-3 had the first and second compounds of the light-emitting layers modified as shown in Table 3 below. Comparative Example 1 did not contain the second compound; the mass percentage of the second compound in Comparative Example 2 was the same as in Examples 1-8; and the mass percentage of the second compound in Comparative Example 3 was the same as in Examples 9-12. Otherwise, the organic electroluminescent devices were prepared using the same procedures as in Examples 1-12.

[0129] Table 3

[0130] Comparative Example First compound (1% by mass) Second compound The third compound 1 5-5 / 9-47 2 / 7-84(30％) 9-47 3 / 7-84(40％→20％) 9-47

[0131] Performance evaluation of organic electroluminescent devices

[0132] The performance test of the organic electroluminescent devices prepared in Examples 1 to 12 and Comparative Examples 1 to 3 of the present application was carried out by using a spectroradiometer CS-2000 (Konica Minolta) and a digital source meter 2420 (Keithley) to measure the CIE1931 chromaticity coordinates (x, y) of the organic electroluminescent devices, the maximum external quantum efficiency of the devices, and the luminance at 1000 cd / m 2 External quantum efficiency and electroluminescence spectrum half-peak width at brightness (unit: nm).

[0133] The device performance results of Examples 1 to 12 and Comparative Examples 1 to 3 are shown in Table 4.

[0134] Table 4

[0135]

[0136]

[0137] Comparing the device performance results of Examples 1 to 12 and Comparative Examples 1 to 3 in Table 4, it can be seen that when other materials in the organic electroluminescent device structure are the same, the organic electroluminescent devices containing the multi-element luminescent composition of Examples 1 to 12 of the present application have significantly improved efficiency and significantly decreased efficiency roll-off compared with the devices of Comparative Examples 1 to 3, indicating that the multi-element doped luminescent composition is beneficial to Energy transfer achieves advantages such as high efficiency and narrow spectrum. Among them, comparing the devices of Examples 9 to 12 with those of Examples 1 to 4, Examples 1 to 4 are devices prepared with the second compound at a constant doping concentration of 30%. The carriers in the device are unbalanced, which reduces the luminous efficiency of the device and increases the efficiency roll-off. The second compound of Examples 9 to 12 is doped in a gradient doping manner, which improves the efficiency and significantly reduces the efficiency roll-off. It can improve the carrier balance in the light-emitting layer, effectively widen the recombination area of ​​the light-emitting layer, reduce the exciton concentration, reduce the annihilation of excitons, polarons, etc. inside the device, and suppress the efficiency roll-off of the device. In terms of the spectral half-width, the half-width of the devices of Examples 5 to 6 is narrower than that of the device of Comparative Example 2. The first compound has a luminescent spectrum characteristic with a narrow half-width. By converting the exciton energy in the second compound to Energy is efficiently transferred to the first compound in a transfer manner, so that the second compound sensitizes the first compound to emit light, and the spectral half-peak width of the device is significantly reduced, thereby achieving device performance with high luminous efficiency and high color purity. In addition, compared with Example 12 and Comparative Example 3, the gradient doping of the ternary luminescent composition compared with the binary luminescent composition with only the second compound and the third compound has improved efficiency roll-off, and the introduction of the first compound narrows the luminescent spectrum of the device in Example 12. This is because Example 12 introduces the first compound, and the exciton energy of the second compound can be The energy is efficiently transferred to the first compound to emit light, and the quantum fluorescence efficiency of the first compound is higher than that of the second compound, so there is a certain improvement in the luminous efficiency and efficiency roll-off.

[0138] The above experimental data show that the novel organic electroluminescent device of the present application has a significant improvement in performance compared with conventional organic light-emitting devices and is expected to be promoted for commercial application.

[0139] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A luminescent composition, characterized in that Composed of a first compound, a second compound, and a third compound; in terms of mass percentage, the mass percentage of the first compound is 0.1 to 20.0%, the mass percentage of the second compound is 5.0 to 60.0%, and the mass percentage of the third compound is 20.0 to 94.9%; The second compound is a thermally activated delayed fluorescent material, and the third compound is a fluorescent material; The first compound is selected from any one of the following compounds: The second compound is selected from any one of formula (7-1) to formula (7-102): The third compound is selected from any one of formula (9-1) to formula (9-99):

2. The luminescent composition according to claim 1, characterized in that The mass percentage of the first compound is a fixed value, the mass percentage of the second compound changes linearly at a constant rate of change, the mass percentage of the third compound changes with the mass percentage of the second compound, and the rate of change ranges from 0.125% / nm to 4% / nm. The difference between the highest mass percentage of the second compound and the lowest mass percentage of the second compound is 5.0 to 20.0%.

3. An organic electroluminescent device comprising a substrate and an anode layer, an organic light-emitting functional layer, and a cathode layer sequentially formed on the substrate, wherein the organic light-emitting functional layer comprises a light-emitting layer, characterized in that: The light-emitting layer is made of the light-emitting composition according to any one of claims 1 to 2.

4. The organic electroluminescent device according to claim 3, characterized in that: The organic light-emitting functional layer includes a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer, and the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer and the electron injection layer are sequentially formed on the anode layer of the substrate; The mass percentage of the second compound on the side close to the hole transport layer is higher than the mass percentage on the side close to the electron transport layer.

Images