Compound, electroluminescent device and preparation method thereof, and display device

Abstract

This application discloses a compound, an electroluminescent device, a method for preparing the same, and a display device. The compound comprises Ar, a coumarin group, and a linking group B for connecting Ar and the coumarin group. Ar is selected from structural units containing aryl and / or heteroaryl groups. The method for preparing the electroluminescent device includes the step of preparing a hole transport layer. In the process of preparing the hole transport layer, a hole transport material layer is first prepared, the material of which includes the compound. Then, the hole transport material layer is treated with a first illumination condition to form a cross-linked structure. Next, an upper functional film is prepared on one side of the hole transport material layer. After the upper functional film is prepared, the hole transport material layer is treated with a second illumination condition to de-crosslink the cross-linked hole transport material.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, specifically to a compound, an electroluminescent device, a method for preparing the same, and a display device. Background Technology

[0002] Electroluminescent devices belong to the category of optoelectronic devices, which are electronic devices that emit light when an electric field is applied. Electroluminescent devices include, but are not limited to, organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs). The light-emitting principle of electroluminescent devices is as follows: electrons are injected from the cathode into the light-emitting region, and holes are injected from the anode into the light-emitting region. Electrons and holes recombine in the light-emitting region to form excitons. These excitons then release photons through radiative transitions, thereby emitting light.

[0003] Electroluminescent devices typically have a "sandwich" structure, consisting of an anode, a functional layer, and a cathode arranged sequentially. The functional layer includes a hole functional layer near the anode, an electron functional layer near the cathode, and a light-emitting layer positioned between the anode and cathode. When solution processing is used to fabricate the functional films, the functional materials (e.g., solvents) used to prepare the upper films can damage the lower films, negatively impacting the photoelectric performance of the electroluminescent device. Taking QLEDs as an example, QLEDs are a new generation of electroluminescent devices based on quantum dots as the light-emitting material. Existing QLEDs suffer from an electron-hole transport imbalance, where electron injection is stronger than hole injection, resulting in a significantly higher number of electrons than holes. This electron-hole injection imbalance leads to a roll-off in QLED efficiency and a shorter lifespan, limiting its application. Furthermore, during QLED fabrication, the solution processing used to prepare other functional films on the hole functional layer can damage the hole functional layer, exacerbating the electron-hole transport imbalance and further negatively impacting the photoelectric performance and lifespan of the QLED.

[0004] Therefore, improving the material of the hole functional layer to reduce the adverse effects on the hole functional layer when other functional films are formed on it, especially reducing the adverse effects on the hole functional layer when the light-emitting layer is formed on it using the solution method, is of great significance to the application and development of electroluminescent devices. Summary of the Invention

[0005] This application provides a compound, an electroluminescent device, a method for preparing the same, and a display device. By providing a compound with reversible light response characteristics as a hole-functional material for the electroluminescent device, the damage to the hole-functional layer caused by raw materials and / or preparation processes is reduced when other functional thin films are prepared on the hole-functional layer.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, this application provides a compound having the structure shown in the general formula (I):

[0008]

[0009] In general formula (Ⅰ), Ar is selected from structural units containing aryl and / or heteroaryl groups, B is a linking group, and n is greater than or equal to 1.

[0010] Furthermore, the Ar is selected from triarylamine and / or carbazole groups.

[0011] Furthermore, B is selected from an imide group or a group containing an imide group.

[0012] Furthermore, B is composed of linked alkylene and imide groups, and Ar is connected to either the alkylene or the imide group.

[0013] Further, the compound is:

[0014]

[0015] Where n is greater than or equal to 1.

[0016] Secondly, this application also provides a method for preparing a compound, comprising the following steps:

[0017] Provide a mixture of the first compound and the second compound; and

[0018] The mixture was heat-treated in an inert gas atmosphere to obtain the compound;

[0019] The first compound has the structure shown in general formula (II):

[0020]

[0021] In general formula (II), Ar is selected from structural units containing aryl and / or heteroaryl groups, n is greater than or equal to 1, and R1 is selected from amino, carboxyl, amino-containing groups or carboxyl-containing groups.

[0022] The second compound has the structure shown in the general formula (Ⅲ):

[0023]

[0024] In general formula (Ⅲ), R2 is selected from amino, carboxyl, groups containing amino or groups containing carboxyl;

[0025] R1 and R2 are not the same as each other, and R1 and R2 can react to generate B.

[0026] Further, in the mixture, the mass ratio of the first compound to the second compound is 1:(0.3 to 0.8).

[0027] Thirdly, this application provides an electroluminescent device, comprising:

[0028] anode;

[0029] The cathode is disposed opposite to the anode;

[0030] A light-emitting layer is disposed between the anode and the cathode; and

[0031] A hole transport layer is disposed between the light-emitting layer and the anode;

[0032] The material of the hole transport layer includes any of the compounds described in the first aspect, or compounds prepared by any of the preparation methods described in the second aspect.

[0033] Furthermore, the electroluminescent device further includes an electron transport layer disposed between the light-emitting layer and the cathode.

[0034] Furthermore, the material of the electron transport layer includes metal oxide nanoparticles, which are selected from at least one of ZnO, TiO2, SnO2, Ta2O3, ZrO2, TiLiO, ZnGaO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, and InSnO.

[0035] Further, the material of the light-emitting layer is a quantum dot, which is selected from at least one of group II-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds are selected from at least one of CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, and CdZnSTe; the group III-V compounds are selected from InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP, and InAlNP; and the group I-III-VI compounds are selected from at least one of CuInS2, CuInSe2, and AgInS2.

[0036] Fourthly, this application also provides a method for fabricating an electroluminescent device, used to fabricate an electroluminescent device as described in any of the third aspects, comprising the steps of: providing a stacked structure, and sequentially forming a hole transport layer, a light-emitting layer and a cathode on one side of the stacked structure, wherein the stacked structure is a substrate containing an anode;

[0037] The step of sequentially forming a hole transport layer, a light-emitting layer, and a cathode on one side of the stacked structure includes the following steps:

[0038] A hole transport material layer is prepared on one side of the anode. The material of the hole transport material layer includes any of the compounds described in the first aspect or compounds prepared by any of the preparation methods described in the second aspect. The hole transport material layer is then treated with a first light irradiation condition to obtain a hole transport precursor layer.

[0039] A light-emitting layer is formed on the side of the hole transport precursor layer away from the anode;

[0040] A cathode is formed on the side of the light-emitting layer away from the hole transport layer;

[0041] The stacked structure containing the hole transport precursor layer and the light-emitting layer is processed under a second illumination condition to obtain the hole transport layer.

[0042] Fifthly, this application also provides a method for fabricating an electroluminescent device, used to fabricate an electroluminescent device as described in any of the third aspects, comprising the steps of: providing a stacked structure, and sequentially forming a hole transport layer and an anode on one side of the stacked structure, wherein the stacked structure is a substrate containing a cathode and a light-emitting layer;

[0043] The step of sequentially forming a hole transport layer and an anode on one side of the stacked structure includes the following steps:

[0044] A hole transport material layer is prepared on the side of the light-emitting layer away from the cathode. The material of the hole transport material layer includes any compound as described in the first aspect or a compound prepared by any preparation method as described in the second aspect. The hole transport material layer is then treated with a first illumination condition to obtain a hole transport precursor layer.

[0045] An anode is formed on the side of the hole transport precursor layer away from the light-emitting layer;

[0046] The stacked structure containing the hole transport precursor layer and the anode is processed under a second illumination condition to obtain the hole transport layer.

[0047] Furthermore, the wavelength of light under the first illumination condition is 363 nm to 367 nm, and the wavelength of light under the second illumination condition is 252 nm to 256 nm.

[0048] Sixthly, this application also provides a display device, the display device comprising an electroluminescent device as described in any of the third aspects, or an electroluminescent device prepared by any of the preparation methods described in any of the fourth or fifth aspects.

[0049] This application provides a compound material, an electroluminescent device, a method for preparing the same, and a display device, which have the following technical advantages:

[0050] The compound has the structure shown in general formula (I) and contains a coumarin group with reversible photoresponsive properties. After treatment under a first light irradiation condition, the compound can form a cross-linked structure, thereby exhibiting ideal anti-solvent properties. After treatment under a second light irradiation condition, the cross-linked structure de-crosslinks and re-forms the compound. Compared with the cross-linked structure, the compound has better carrier transport performance.

[0051] The electroluminescent device includes a hole transport layer, the material of which includes a compound having the structure shown in general formula (I), so that the hole transport layer has ideal carrier transport performance, promotes the balance between electron transport and hole transport, and thus improves the photoelectric performance of the electroluminescent device.

[0052] The method for fabricating the electroluminescent device includes the step of fabricating a hole transport layer. In the process of fabricating the hole transport layer, a hole transport material layer is first prepared. Then, the hole transport material layer is treated under a first illumination condition to form a cross-linked structure. Next, an upper functional film is formed on one side of the hole transport material layer. Since the cross-linked hole transport material has better resistance than the uncross-linked hole transport material, such as better solvent resistance and high-temperature resistance, it can effectively avoid damage to the hole transport material caused by the raw materials (e.g., solvents) used to prepare the upper functional film or the fabrication process of the upper functional film (e.g., high temperature). After the upper functional film is prepared, the hole transport material layer is treated under a second illumination condition to de-crosslink the cross-linked hole transport material. The de-crosslinked hole transport material has better carrier transport performance, thereby improving the hole mobility of the hole transport layer and helping to improve the problem of electron-hole transport imbalance in electroluminescent devices.

[0053] The display device includes the electroluminescent device, which has the advantage of ideal display effect. Attached Figure Description

[0054] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0055] Figure 1 This is a schematic flowchart illustrating a method for preparing a hole transport material according to an embodiment of this application.

[0056] Figure 2 This is a schematic diagram of the structure of an electroluminescent device provided in an embodiment of this application.

[0057] Figure 3 This is a schematic diagram of another electroluminescent device provided in an embodiment of this application.

[0058] Figure 4 This is a schematic flowchart illustrating a method for fabricating an electroluminescent device according to an embodiment of this application.

[0059] Figure 5 This is a schematic flowchart illustrating another method for fabricating an electroluminescent device provided in an embodiment of this application.

[0060] Figure 6 This is a schematic diagram of an electroluminescent device with an upright structure provided in Example 1.

[0061] Figure 7 This is a schematic diagram of an electroluminescent device with an inverted structure provided in Example 2.

[0062] Figure 8The images show the electroluminescence morphology of the electroluminescent devices of Examples 1, 2, Comparative Example 1, and 2, where A is the electroluminescence morphology of the electroluminescent device of Example 1, B is the electroluminescence morphology of the electroluminescent device of Example 2, C is the electroluminescence morphology of the electroluminescent device of Comparative Example 1, and D is the electroluminescence morphology of the electroluminescent device of Comparative Example 2.

[0063] Figure 9 The graphs show the brightness-current efficiency of the electroluminescent devices in Example 1 and Comparative Example 2. Detailed Implementation

[0064] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0066] 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," and the terms "a plurality of" or "multiple layers" mean two or more layers. Various embodiments of this application may exist in a range format; it should be understood that the description in a range format 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.

[0067] This application provides a compound having the structure shown in the general formula (Ⅰ):

[0068]

[0069] In general formula (Ⅰ), Ar is selected from structural units containing aryl and / or heteroaryl groups, B is a linking group, and n is greater than or equal to 1.

[0070] The compound contains a coumarin group, and the coumarin group is linked to Ar through a linking group B. Coumarin has reversible photoresponsive properties, as shown in the reaction formula (1) below. Two adjacent coumarin molecules can undergo chemical cross-linking to form a four-membered ring structure under 365 nm ultraviolet light irradiation. The four-membered ring structure can undergo photodecomposition cross-linking reaction under 254 nm ultraviolet light irradiation. Therefore, the compound has reversible photoresponsive properties, that is: under 365 nm ultraviolet light irradiation, it can form a cross-linked structure, thereby having ideal anti-solvent properties; under 254 nm ultraviolet light irradiation, the cross-linked structure de-crosslinks and re-forms the compound. Compared with the cross-linked structure, the compound has better carrier transport performance.

[0071]

[0072] In some embodiments of this application, Ar in general formula (I) is selected from triarylamine and / or carbazole.

[0073] For example, Ar has the structure shown in the following general formula (Ⅳ):

[0074]

[0075] In general formula (Ⅳ), R x R y and R z Each atom is independently selected from hydrogen, alkyl, alkoxy, halogen, aromatic, or heteroaryl groups. As an example, Ar is triphenylamine.

[0076] As an example, Ar has the structure shown in the general formula (V):

[0077]

[0078] In general formula (V), R r R s and R t They are independently selected from hydrogen atoms, alkyl groups, alkoxy groups, halogen atoms, aromatic groups, or heteroaryl groups.

[0079] In some embodiments of this application, B in general formula (I) is selected from an imide group or a group containing an imide group.

[0080] In some embodiments of this application, B is composed of an alkylene group and an imide group, and Ar is connected to either an alkylene group or an imide group. As an example: B is composed of a methylene group and an imide group, with the imide group connected to Ar, one end of the methylene group connected to the imide group, and the other end of the methylene group connected to a coumarin group.

[0081] This application also provides a method for preparing a compound, used to prepare any of the compounds described in the embodiments of this application, such as... Figure 1 As shown, the preparation method includes the following steps:

[0082] 10. To provide a mixture of the first compound and the second compound;

[0083] 20. The mixture from step 10 is subjected to heat treatment in an inert gas atmosphere to obtain the compound.

[0084] In step 10, the first compound has the structure shown in general formula (II):

[0085]

[0086] In general formula (II), Ar is selected from structural units containing aryl and / or heteroaryl groups, n is greater than or equal to 1, and R1 is selected from amino, carboxyl, amino-containing groups or carboxyl-containing groups.

[0087] In step 10, the second compound has the structure shown in the following general formula (Ⅲ):

[0088]

[0089] In general formula (Ⅲ), R2 is selected from amino, carboxyl, groups containing amino or groups containing carboxyl.

[0090] It should be noted that for the first and second compounds, R1 and R2 are different from each other, and R1 and R2 can react to generate the linking group B in general formula (I). For example, R1 is a carboxyl group and R2 is an amino group, or R1 is an amino group and R2 is a carboxyl group. R1 and R2 can react to combine to form an amide group as the linking group B, or R1 is a carboxyl group and R2 is an alkylamino group (e.g., -NH2-CH2-).

[0091] In step 20, the "inert gas" can be at least one of nitrogen, argon, helium, neon, krypton, xenon, and radon. The "heat treatment" can be either isothermal heat treatment or non-isothermal heat treatment (e.g., temperature gradient).

[0092] As an example, when A is triphenylamine, the heat treatment temperature is 120℃ and the heat treatment time is 10 min, and the reaction formula is shown in equation (II) below:

[0093]

[0094] In some embodiments of this application, in step 10, the mass ratio of the first compound to the second compound in the mixture is 1:(0.3~0.8). If the amount of the second compound added is too large, there will be an excess of the second compound in the hole transport material, and the improvement of the carrier transport performance of the hole transport material will be limited. If the amount of the second compound added is too small, there will be an excess of the first compound in the hole transport material, and the solvent resistance of the first compound is poor, so the improvement of the solvent resistance performance of the hole transport material will be limited.

[0095] This application also provides an electroluminescent device, such as... Figure 2 As shown, the electroluminescent device 1 includes an anode 11, a cathode 12, a light-emitting layer 13, and a hole transport layer 14. The anode 11 and cathode 12 are disposed opposite each other, the light-emitting layer 13 is disposed between the anode 11 and cathode 12, and the hole transport layer 14 is disposed between the light-emitting layer 13 and anode 11. The material of the hole transport layer 14 includes any of the compounds described in the embodiments of this application or compounds prepared by any of the preparation methods described in the embodiments of this application, so that the hole transport layer 14 has ideal carrier transport performance, promotes the balance of electron transport and hole transport, and thereby improves the photoelectric performance of the electroluminescent device.

[0096] In the electroluminescent device 1, the materials of the anode 11 and the cathode 12 can be one or more of metals, carbon materials, and metal oxides. For example, the metals can be one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg; the carbon materials can be one or more of graphite, carbon nanotubes, graphene, and carbon fibers; and the metal oxides can be doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO. A composite electrode consisting of a metal sandwiched between doped or undoped transparent metal oxides, including but not limited to one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. The thickness of the anode can be, for example, 60 nm to 150 nm, and the thickness of the cathode can be, for example, 50 nm to 200 nm.

[0097] It is understood that the electroluminescent device 1 may also include other functional layers that promote hole transport, such as a hole injection layer disposed between the hole transport layer and the anode. The material of the hole injection layer includes, but is not limited to, 3,4-ethylenedioxythiophene monomer (PEDOT), styrene sulfonate (PSS), copper phthalocyanine (CuPc), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HATCN), transition metal oxides, and transition metal chalcogenides, wherein the transition metal oxide may be NiO. x MoO x WO x CrO x And one or more of CuO, the metal chalcogenide compound being MoS x MoSe x WS x 、WSe x And one or more of CuS, the thickness of the hole injection layer can be, for example, 15 nm to 30 nm.

[0098] In some embodiments of this application, such as Figure 3 As shown, in Figure 2 Based on the electroluminescent device 1 shown, the electroluminescent device 1 further includes an electron transport layer 15, which is disposed between the light-emitting layer 13 and the cathode 12.

[0099] The electron transport 15 material includes, but is not limited to, metal oxide nanoparticles and doped metal oxide nanoparticles. The metal oxide nanoparticles are oxide semiconductor nanoparticle materials with electron transport capabilities, such as at least one selected from ZnO, TiO2, SnO2, Ta2O3, ZrO2, TiLiO, ZnGaO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, and InSnO. The doped metal oxide nanoparticles include a dopant element and a host metal element, which are not the same. The dopant element can be a metal or a non-metal, for example, selected from one or more of Al, Ga, Li, Cd, Cr, In, Cu, Fe, Mg, Sn, Sb, Ag, Ti, La, Nb, Mn, Zn, and Ce. The thickness of the electron transport 15 can be, for example, from 25 nm to 50 nm.

[0100] It is understood that the electroluminescent device 1 may also include other functional layers that promote electron transport, such as an electron injection layer disposed between the electron transport layer 15 and the cathode 12. The material of the electron injection layer includes, but is not limited to, organophosphorus compounds, lithium halides and lithium organic complexes. The organophosphorus compounds may be, for example, at least one of organophosphorus oxides, organothiophosphorus compounds and organophosphorus selenides. The lithium organic complexes may be, for example, lithium 8-hydroxyquinoline.

[0101] In some embodiments of this application, the material of the light-emitting layer 13 is a quantum dot. The quantum dot can be at least one of red quantum dots, green quantum dots, and blue quantum dots. The quantum dot can be selected from, but is not limited to, at least one of single-structure quantum dots, core-shell structure quantum dots, inorganic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots. For a single-structure quantum dot, the quantum dot includes, but is not limited to, at least one of group II-VI compounds, group III-V compounds, and group I-III-VI compounds. For example, group II-VI compounds may be at least one of CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, and CdZnSTe. For example, group III-V compounds may be at least one of InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP, and InAlNP. For example, group I-III-VI compounds may be at least one of CuInS2, CuInSe2, and AgInS2. For core-shell quantum dots, the core and shell materials are independently selected from at least one of group II-VI, III-V, and I-III-VI compounds. Blue quantum dots can be, for example, cadmium zinc sulfide / zinc sulfide (CdZnS / ZnS) with a particle size of 2 nm to 5 nm and an emission wavelength of 450 nm; red quantum dots can be, for example, indium phosphide / zinc sulfide (InP / ZnS) with a particle size of 9 nm to 11 nm and an emission wavelength of 625 nm; green quantum dots can be, for example, indium phosphide / zinc sulfide (InP / ZnS) with a particle size of 4 nm to 6 nm and an emission wavelength of 530 nm. The general structural formula for inorganic perovskite quantum dots is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, and M includes, but is not limited to, Pb. 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Or Eu 2+ X is a halide anion, including but not limited to Cl. - ,Br - Or I - The general structural formula for organic-inorganic hybrid perovskite quantum dots is BMX3, where B is an organic amine cation, including but not limited to CH3(CH2). n -2NH 3+ (n≥2) or NH3(CH2) n NH3 2+ (n≥2), M is a divalent metal cation, and M includes, but is not limited to, Pb. 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Or Eu 2+ X is a halide anion, including but not limited to Cl. - ,Br - Or I - The particle size of the quantum dots can be, for example, 6 nm to 10 nm, and the thickness of the light-emitting layer 13 can be, for example, 10 nm to 30 nm.

[0102] This application also provides a method for fabricating an electroluminescent device, mainly applicable to the fabrication of an electroluminescent diode with a positive-position structure. The fabrication method includes the following steps: providing a stacked structure; sequentially fabricating a hole transport layer, a light-emitting layer, and a cathode on one side of the stacked structure; the stacked structure is a substrate containing an anode; wherein, the sequential fabrication of the hole transport layer, light-emitting layer, and cathode on one side of the stacked structure... Figure 4 As shown, it includes the following steps:

[0103] 100. A hole transport material layer is prepared on one side of the anode. The material of the hole transport material layer includes any of the compounds described in the embodiments of this application or the compounds prepared by any of the preparation methods described in the embodiments of this application. Then, the hole transport material layer is treated with the first light irradiation condition to obtain a hole transport precursor layer.

[0104] 200. A light-emitting layer is formed on the side of the hole transport precursor layer away from the anode;

[0105] 300. A cathode is formed on the side of the light-emitting layer away from the hole transport layer;

[0106] 400. The stacked structure containing the hole transport precursor layer and the light emission layer is processed using the second illumination condition to obtain the hole transport layer.

[0107] The hole transport material layer and the light-emitting layer are prepared using solution methods. Solution methods include, but are not limited to, spin coating, coating, inkjet printing, blade coating, dip-coating, immersion, spraying, roller coating, or casting. It should be noted that after the wet film is prepared by the solution method, a drying process is required. The drying process includes all processes that can enable the wet film to obtain higher energy and transform into a dry film. The drying process can be, for example, heat treatment. The cathode is prepared using, but is not limited to, deposition methods and solution methods. Deposition methods include chemical methods and physical methods. Chemical methods include, but are not limited to, chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, or co-precipitation. Physical methods include, but are not limited to, thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion plating, physical vapor deposition, atomic layer deposition, or pulsed laser deposition.

[0108] In step 100, a hole transport material layer can be formed directly on one side of the anode, or indirectly on the other side. Specifically, a functional thin film promoting electron-hole transport balance can be first formed on one side of the anode using a solution method or deposition. Then, a hole transport material layer is formed on the side of the functional thin film away from the anode. For example, a hole injection layer can be formed on one side of the anode using a solution method or deposition, and then a hole transport material layer can be formed on the side of the hole injection layer away from the anode. After treatment under the first illumination condition, the hole transport material layer forms a cross-linked hole transport material. This cross-linked hole transport material exhibits ideal resistance. Therefore, when forming other functional thin films on the side of the hole transport precursor layer away from the anode, damage to the hole transport material can be avoided by the raw materials (e.g., solvents) or preparation processes (e.g., high temperatures) used to prepare the other functional thin films. For example, when forming a light-emitting layer on the side of the hole transport precursor layer away from the anode using a solution method, the cross-linked hole transport material has ideal solvent resistance, effectively mitigating the adverse effects of the solvent in the light-emitting material solution on the hole transport material layer.

[0109] In some embodiments of this application, the wavelength of the first illumination condition is 363 nm to 367 nm. In one embodiment of this application, the first illumination condition is: a wavelength of 365 nm, a pulse width of 22 ns for the ultraviolet laser, a power of 5 W, a frequency of 1.2 Hz, and a duration of 90 s.

[0110] In 300, a cathode can be formed directly on the side of the light-emitting layer away from the hole transport layer, or indirectly on the side of the light-emitting layer away from the hole transport layer. That is, an electronic functional layer can be formed first on the side of the light-emitting layer away from the hole transport layer using a solution method or a deposition method, and then a hole transport material layer can be formed on the side of the electronic functional layer away from the light-emitting layer. For example, an electron transport layer can be formed first on the side of the light-emitting layer away from the hole transport layer using a solution method or a deposition method, and then a cathode can be formed on the side of the electron transport layer away from the light-emitting layer.

[0111] In 400, after being treated with the second illumination condition, the hole transport material with cross-linked structure in the hole transport precursor layer undergoes photode-crosslinking. The hole transport material formed by de-crosslinking has better carrier transport performance, thereby improving the hole mobility of the hole transport layer and helping to improve the problem of electron-hole transport imbalance in electroluminescent devices.

[0112] In some embodiments of this application, the wavelength of the second illumination condition is 252 nm to 256 nm. In one embodiment of this application, the second illumination condition is: a wavelength of 254 nm, a pulse width of 22 ns for the ultraviolet laser, a power of 5 W, a frequency of 1.2 Hz, and a duration of 90 s.

[0113] It should be noted that the order of 300 and 400 is not specifically limited. The process can be implemented either 300 first, then 400, or 400 first, then 300, provided that the following condition is met: other functional thin films must be prepared on the hole transport precursor layer before the second illumination treatment is performed. The second illumination treatment cannot be performed immediately after the hole transport precursor layer is prepared.

[0114] This application also provides a method for fabricating an electroluminescent device, used to fabricate any of the electroluminescent devices described in this application, mainly applicable to fabricating electroluminescent diodes with an inverted structure. The fabrication method includes the following steps: providing a stacked structure, and sequentially forming a hole transport layer and an anode on one side of the stacked structure. The stacked structure is a substrate containing a cathode and a light-emitting layer. Specifically, the step of sequentially forming the hole transport layer and the anode on one side of the stacked structure is described below. Figure 5 As shown, it includes the following steps:

[0115] 100'. A hole transport material layer is prepared on the side of the light-emitting layer away from the cathode. The material of the hole transport material layer includes any of the compounds described in the embodiments of this application or the compounds prepared by any of the preparation methods described in the embodiments of this application. Then, the hole transport material layer is treated with the first illumination condition to obtain the hole transport precursor layer.

[0116] 200', An anode is formed on the side of the hole transport precursor layer away from the light-emitting layer;

[0117] 300'. The stacked structure containing the hole transport precursor layer and the anode is processed under the second illumination condition to obtain the hole transport layer.

[0118] The methods for preparing the anode include, but are not limited to, deposition and solution methods, as described above. Furthermore, the first illumination conditions in 100' and the second illumination conditions in 300' are as described above.

[0119] In the 100' method, a hole transport material layer can be directly formed on the side of the light-emitting layer away from the cathode, or indirectly formed on the same side. Specifically, other functional films promoting electron-hole transport balance can be first formed on the side of the light-emitting layer away from the cathode using a solution method or deposition method, and then a hole transport material layer can be formed on the side of the functional film away from the light-emitting layer. After treatment under the first illumination condition, the hole transport material layer forms a cross-linked hole transport material. This cross-linked hole transport material exhibits ideal resistance. Therefore, when forming other functional films on the side of the hole transport precursor layer away from the anode, damage to the hole transport material can be avoided from the raw materials (e.g., solvents) or preparation processes (e.g., high temperatures) used to prepare the other functional films. For example, when forming the anode on the side of the hole transport precursor layer away from the light-emitting layer using evaporation or sputtering methods, the ideal high-temperature resistance of the cross-linked hole transport material effectively mitigates the adverse effects of the high-temperature conditions required for evaporation or sputtering on the hole transport material layer.

[0120] In 200', an anode can be formed directly on the side of the hole transport precursor layer away from the light-emitting layer, or indirectly on the side of the hole transport precursor layer away from the light-emitting layer. That is, other functional films that promote electron-hole transport balance are first formed on the side of the hole transport precursor layer away from the light-emitting layer using a solution method or deposition method. For example, the functional film is a hole injection layer. Then, an anode is formed on the side of the functional film away from the hole transport precursor layer.

[0121] In 300', after being treated with the second illumination condition, the hole transport material with cross-linked structure in the hole transport precursor layer undergoes photode-crosslinking. The hole transport material formed by de-crosslinking has better carrier transport performance, thereby improving the hole mobility of the hole transport layer and helping to improve the problem of electron-hole transport imbalance in electroluminescent devices.

[0122] It should be noted that when the anode is indirectly formed on the side of the hole transport precursor layer away from the light-emitting layer, the order of steps 200' and 300' is not specifically limited. Steps 200' and 300' can be performed first, or step S300' and 200' can be performed first. However, the following condition must be met: other functional films must be prepared on the side of the hole transport precursor layer away from the light-emitting layer first, and then step 300' can be performed. The hole transport precursor layer cannot be subjected to a second illumination condition treatment immediately after preparation. Furthermore, compared to hole transport materials using thermal crosslinking, compounds prepared using the compounds of this application or the preparation methods of this application, as hole transport materials for electroluminescent devices, have advantages such as ideal solution processing characteristics and mild crosslinking reaction conditions (no need for high-temperature crosslinking or the addition of photosensitizers), which helps reduce the manufacturing cost of electroluminescent devices.

[0123] This application also provides a display device, including any of the electroluminescent devices described in this application or electroluminescent devices prepared by any of the methods described in this application. The display device can be any electronic product with display functionality, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0124] The technical solutions and effects of this application will be described in detail below through specific embodiments, comparative examples and experimental examples. The following embodiments are only some embodiments of this application and are not intended to limit this application.

[0125] Example 1

[0126] This embodiment provides an electroluminescent device and its fabrication method. The electroluminescent device in this embodiment is a quantum dot light-emitting diode with a positive-position structure, such as... Figure 6 As shown, in the direction from bottom to top, the electroluminescent device includes a substrate 10, an anode 11, a hole injection layer 16, a hole transport layer 14, a light-emitting layer 13, an electron transport layer 15, and a cathode 12 arranged sequentially.

[0127] The materials and thicknesses of each layer in the electroluminescent device of this embodiment are as follows:

[0128] The substrate 11 is made of glass and has a thickness of 2 mm.

[0129] The anode 11 is made of ITO and has a thickness of 15 nm.

[0130] The cathode 12 is made of silver and has a thickness of 20 nm.

[0131] The material of the light-emitting layer 13 is ZnS, and the thickness of the light-emitting layer 13 is 15nm;

[0132] The electron transport layer 15 is made of nano-ZnO with a particle size of 8 nm, and the thickness of the electron transport layer 15 is 25 nm.

[0133] The hole injection layer 16 is made of PEDOT:PSS, and the hole injection layer 13 has a thickness of 30nm.

[0134] The hole transport layer 14 is made of a compound as shown in structural formula (VI), and the thickness of the hole transport layer 14 is 40 nm.

[0135]

[0136] The fabrication method of the electroluminescent device in this embodiment includes the following steps:

[0137] S1.1 Provide a substrate containing an anode (ITO), and spin-coat a PEDOT-PSS aqueous solution with a concentration of 10 mg / mL on the side of the anode away from the substrate under normal temperature and pressure. Then, place it under constant temperature heat treatment at 150°C for 15 min and let it stand to cool for 5 min to obtain a hole injection layer.

[0138] S1.2 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), spin-coat hole transport ink on the side of the hole injection layer away from the anode in step S1.1, then place it at 80℃ for constant temperature heat treatment for 15min, and let it cool for 5min to obtain a hole transport material layer. Then, process the hole transport material layer under the first illumination conditions. The first illumination conditions are: light wavelength of 365nm, ultraviolet laser pulse width of 22ns, power of 5W, frequency of 1.2Hz, and time of 90s to obtain a hole transport precursor layer.

[0139] S1.3 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), spin-coat a ZnS-n-octane solution with a concentration of 20mg / mL on the side of the hole transport precursor layer away from the hole injection layer in step S1.2, then heat-treat at 80℃ for 10min, and let it stand and cool for 5min to obtain the light-emitting layer.

[0140] S1.4. The hole propagation precursor layer is processed using the second illumination conditions, wherein the second illumination conditions are: light wavelength of 254nm, ultraviolet laser pulse width of 22ns, power of 5W, frequency of 1.2Hz, and duration of 90s, to obtain the hole propagation layer.

[0141] S1.5 Under normal temperature and pressure nitrogen environment (H2O and O2 content less than 5ppm), spin-coat a nano ZnO-ethanol solution with a concentration of 30mg / mL on the side of the light-emitting layer away from the hole transport layer, and then heat-treat at 80℃ for 20min to obtain the electron transport layer.

[0142] S1.6, in a vacuum degree less than 1×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the electron transport layer away from the light-emitting layer in step S1.5 to obtain a cathode, which is then packaged to obtain an electroluminescent device.

[0143] The hole transport material involved in the above preparation method is prepared as follows: 3 mg of carboxyl-substituted polymeric triarylamine (commercially available) and 1.5 mg of amino-substituted coumarin (commercially available) are mixed and dissolved in 0.5 mL of chlorobenzene solvent to obtain a mixture; the mixture is subjected to constant temperature heat treatment at 120 °C for 10 min under a nitrogen atmosphere at room temperature and pressure.

[0144] Among them, the carboxyl-substituted polymeric triarylamine has the structure shown in formula (VII) and a number-average molecular weight of 11,000:

[0145]

[0146] Amino-substituted coumarins have the structure shown in formula (VIII):

[0147]

[0148] Example 2

[0149] This embodiment provides an electroluminescent device and its fabrication method. The electroluminescent device in this embodiment is a quantum dot light-emitting diode with an inverted structure, such as... Figure 7 As shown, in the direction from bottom to top, the electroluminescent device includes a substrate 10, a cathode 12, an electron transport layer 15, a light-emitting layer 13, a hole transport layer 14, a hole injection layer 16, and an anode 11 arranged sequentially.

[0150] The materials and thicknesses of each layer in the electroluminescent device of this embodiment are the same as those in Embodiment 1, and the preparation method of the hole transport material is the same as that in Embodiment 1.

[0151] The fabrication method of the electroluminescent device in this embodiment includes the following steps:

[0152] S2.1. Provide a substrate containing a cathode (Ag), and spin-coat a nano ZnO-ethanol solution with a concentration of 30 mg / mL on the side of the cathode away from the substrate under a nitrogen atmosphere (H2O and O2 content less than 5 ppm) at room temperature and pressure. Then heat-treat at 80°C for 20 min to obtain an electron transport layer.

[0153] S2.2 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), spin-coat a ZnS-n-octane solution with a concentration of 20mg / mL on the side of the electron transport layer away from the cathode in step S2.1, then heat-treat at 80℃ for 10min, and let it stand and cool for 5min to obtain the light-emitting layer.

[0154] S2.3 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), hole transport ink is spin-coated on the side of the light-emitting layer away from the electron transport layer in step S2.2. Then, it is placed at 80°C for constant temperature heat treatment for 15 minutes and allowed to cool for 5 minutes to obtain a hole transport material layer. Then, the hole transport material layer is treated with the first illumination conditions. The first illumination conditions are: light wavelength of 365nm, ultraviolet laser pulse width of 22ns, power of 5W, frequency of 1.2Hz, and time of 90s to obtain a hole transport precursor layer.

[0155] S2.4 Under normal temperature and pressure, spin-coat a 10 mg / mL PEDOT-PSS aqueous solution on the side of the hole transport precursor layer away from the light-emitting layer in step S2.3, then place it at 150°C for constant temperature heat treatment for 15 min, and let it stand and cool for 5 min to obtain the hole injection layer.

[0156] S2.5. The hole propagation precursor layer is processed using the second illumination conditions, wherein the second illumination conditions are: light wavelength of 254nm, ultraviolet laser pulse width of 22ns, power of 5W, frequency of 1.2Hz, and duration of 90s, to obtain the hole propagation layer.

[0157] S2.6 Sputter ITO on the side of the hole injection layer away from the hole transport layer to obtain the anode, and then encapsulate it to obtain an electroluminescent device.

[0158] Example 3

[0159] This embodiment provides an electroluminescent device and its fabrication method. Compared with the electroluminescent device of Embodiment 1, the only difference between the electroluminescent device of this embodiment and the one in which the hole transport layer is made of a different material, is that the hole transport layer of this embodiment has the structure shown in formula (IX):

[0160]

[0161] The preparation method of the hole transport layer material in this embodiment is as follows: 3 mg of carboxyl-substituted carbazole (preparation method reference: Fang Xubin, Fang Lei and Gou Shaohua. Research progress on synthetic methods of carbazole and its derivatives [J]. Organic Chemistry, 2012, 32, 1217-1231) and 1.5 mg of amino-substituted coumarin (the same as the amino-substituted coumarin in Example 1) are mixed and dissolved in 0.5 mL of chlorobenzene solvent to obtain a mixture; the mixture is subjected to constant temperature heat treatment at 120 °C for 10 min under a nitrogen atmosphere at room temperature and pressure. The carboxyl-substituted carbazole has the structure shown in formula (X):

[0162]

[0163] The fabrication method of the electroluminescent device in this embodiment is the same as that in Example 1.

[0164] Comparative Example 1

[0165] This comparative example provides an electroluminescent device and its preparation method. Compared with the electroluminescent device of Example 1, the only difference of the electroluminescent device of this comparative example is that the material of the hole transport layer is replaced by the compound shown in structural formula (Ⅳ) with "TFB".

[0166] Compared with the preparation method of the electroluminescent device in Example 1, the only difference in the preparation method of the electroluminescent device in this comparative example is that step S1.4 is omitted and step S1.2 is replaced with "under a nitrogen environment at room temperature and pressure (H2O and O2 content less than 5ppm), spin-coating a TFB-chlorobenzene solution with a concentration of 8mg / mL on the side of the hole injection layer away from the anode in step S1.1, and then placing it under constant temperature heat treatment at 80℃ for 10min".

[0167] Comparative Example 2

[0168] This comparative example provides an electroluminescent device and its preparation method. Compared with the electroluminescent device of Example 1, the only difference of the electroluminescent device of this comparative example is that the material of the hole transport layer is replaced by the compound shown in structural formula (VI) with the material of the hole transport precursor layer in Example 1 (the compound shown in structural formula (VI) is photocrosslinked to form a compound), that is, the hole transport precursor layer of Example 1 is the hole transport layer of this comparative example.

[0169] Compared with the preparation method of the electroluminescent device in Example 1, the difference in the preparation method of the electroluminescent device in this comparative example is only that: step S1.4 is omitted, and step S1.2 is replaced with "under a nitrogen environment at room temperature and pressure (H2O and O2 content less than 5ppm), hole transport ink is spin-coated on the side of the hole injection layer away from the anode in step S1.1, and then placed at 80°C for constant temperature heat treatment for 15min, and then allowed to cool for 5min to obtain a hole transport material layer, and then the hole transport material layer is treated with the first illumination condition, which is: light wavelength of 365nm, ultraviolet laser pulse width of 22ns, power of 5W, frequency of 1.2Hz, and time of 90s to obtain a hole transport layer."

[0170] Test case

[0171] The electroluminescent devices of Examples 1, 2, Comparative Example 1, and 2 were subjected to performance tests. The performance test parameters were: the brightness (L, cd / m2) of the electroluminescent device under a constant current drive of 2mA, the time required for the brightness of the electroluminescent device to decay from 100% to 95% (T95, h), and the maximum external quantum efficiency (EQE) of the electroluminescent device. max The electroluminescence morphology of the electroluminescent device was measured using an optical microscope, and the time required for the brightness of the electroluminescent device to decay from 100% to 95% at a brightness of 1000 nits (T95-1K,h) and the current efficiency of the electroluminescent device (CE-1K,cd / A) were also measured. The performance test results are detailed in Table 1 below:

[0172] Table 1. Performance test results of the electroluminescent devices in Examples 1, 2, Comparative Example 1, and Comparative Example 2.

[0173]

[0174]

[0175] Note: In Table 1, "N / A" indicates that it cannot be detected.

[0176] As shown in Table 1, compared with the electroluminescent devices of Comparative Examples 1 and 2, the electroluminescent devices of Examples 1 to 3 have significant advantages in photoelectric performance and working life. The various performance test parameters of the electroluminescent devices of Examples 1 to 3 are all better than those of Comparative Examples 1 and 2. This indicates that when the hole transport layer material in the electroluminescent device is a compound represented by general formula (Ⅰ) and is prepared by the preparation method described in the embodiments of this application, it can avoid damage to the hole transport material and improve the hole mobility of the hole transport layer, thereby promoting the internal charge balance of the electroluminescent device, which is beneficial to improving the photoelectric performance and extending the working life of the electroluminescent device.

[0177] Depend on Figure 8 It can be seen that the electroluminescent devices of Examples 1, 2 and Comparative Example 2 have ideal electroluminescent morphology and high electroluminescent uniformity, while the electroluminescent device of Comparative Example 1 has poor electroluminescent uniformity. This indicates that the hole transport material with cross-linked structure has ideal tolerance, so that the hole transport layer in the electroluminescent devices of Examples 1, 2 and Comparative Example 2 is not damaged, while the hole transport layer in the electroluminescent device of Comparative Example 1 is damaged due to the erosion of quantum dot ink, resulting in the electroluminescent device of Comparative Example 1 being impractical.

[0178] Furthermore, the current efficiency of the electroluminescent devices of Example 1 and Comparative Example 2 at different brightness levels was tested, and the results are as follows: Figure 9 As shown, the electroluminescent device of Example 1 operates at low brightness (brightness less than 2 × 10⁻⁶). 4 It still exhibits high current efficiency at cd / m2, and at high brightness (brightness greater than or equal to 4×10⁻⁶ cd / m²), it also has high current efficiency. 4 Under cd / m2 conditions, the current efficiency shows a stable trend, which is beneficial to the working stability of the electroluminescent device; the electroluminescent device in Example 2 exhibits stable current efficiency at low brightness (brightness less than 2×10⁻⁶ cd / m2), which is conducive to the working stability of the electroluminescent device; the electroluminescent device in Example 2 operates at low brightness (brightness less than 2×10⁻⁶ cd / m2) 4 The current efficiency is low at cd / m2. As the brightness increases, the current efficiency increases accordingly, but the change is large, which causes the working stability of the electroluminescent device to decrease. This indicates that the hole transport material with cross-linked structure has a negative impact on the carrier mobility of the hole transport layer, resulting in a decrease in the hole mobility of the hole transport layer, which is not conducive to the internal charge balance of the electroluminescent device.

[0179] The hole transport material, electroluminescent device, its preparation method, and display device provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core ideas of this application; those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A compound, characterized in that, The compound has the structure shown in the following general formula (Ⅰ): (Ⅰ) In general formula (Ⅰ), Ar is selected from triphenylamino or carbazole, and B is selected from amide; n is greater than or equal to 1.

2. The compound according to claim 1, characterized in that, The compound is: and / or ; Where n is greater than or equal to 1.

3. A method for preparing a compound, characterized in that, The method for preparing the compound as described in claim 1 or 2 comprises the following steps: Provide a mixture of the first compound and the second compound; and The mixture was heat-treated in an inert gas atmosphere to obtain the compound; The first compound has the structure shown in general formula (II): (Ⅱ) In general formula (II), Ar is selected from triphenylamino or carbazole, n is greater than or equal to 1, and R1 is selected from amino or carboxyl. The second compound has the structure shown in the general formula (Ⅲ): (Ⅲ) In general formula (Ⅲ), R2 is selected from amino or carboxyl groups; R1 and R2 are not the same as each other, and R1 and R2 can react to generate B.

4. The preparation method according to claim 3, characterized in that, In the mixture, the mass ratio of the first compound to the second compound is 1:(0.3 to 0.8).

5. An electroluminescent device, characterized in that, include: anode; The cathode is disposed opposite to the anode; A light-emitting layer is disposed between the anode and the cathode; as well as A hole transport layer is disposed between the light-emitting layer and the anode; The material of the hole transport layer includes the compound as described in claim 1 or 2, or the compound prepared by the method described in claim 3 or 4.

6. The electroluminescent device according to claim 5, characterized in that, The electroluminescent device further includes an electron transport layer disposed between the light-emitting layer and the cathode.

7. The electroluminescent device according to claim 6, characterized in that, The electron transport layer is made of metal oxide nanoparticles, which are selected from at least one of ZnO, TiO2, SnO2, Ta2O3, ZrO2, TiLiO, ZnGaO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, and InSnO.

8. The electroluminescent device according to claim 5, characterized in that, The material of the light-emitting layer is a quantum dot, which is selected from at least one of group II-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds are selected from at least one of CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, and CdZnSTe; the group III-V compounds are selected from InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP, and InAlNP; the group I-III-VI compounds are selected from at least one of CuInS2, CuInSe2, and AgInS2.

9. A method for fabricating an electroluminescent device, characterized in that, The steps include: providing a stacked structure, and sequentially forming a hole transport layer, a light-emitting layer, and a cathode on one side of the stacked structure, wherein the stacked structure is a substrate containing an anode; The step of sequentially forming a hole transport layer, a light-emitting layer, and a cathode on one side of the stacked structure includes the following steps: A hole transport material layer is prepared on one side of the anode. The material of the hole transport material layer includes the compound as described in claim 1 or 2, or the compound prepared by the method as described in claim 3 or 4. The hole transport material layer is then treated with a first light irradiation condition to obtain a hole transport precursor layer. A light-emitting layer is formed on the side of the hole transport precursor layer away from the anode; A cathode is formed on the side of the light-emitting layer away from the hole transport layer; The stacked structure containing the hole transport precursor layer and the light-emitting layer is processed under a second illumination condition to obtain the hole transport layer.

10. A method for fabricating an electroluminescent device, characterized in that, The steps include: providing a stacked structure, and sequentially forming a hole transport layer and an anode on one side of the stacked structure, wherein the stacked structure is a substrate containing a cathode and a light-emitting layer; The step of sequentially forming a hole transport layer and an anode on one side of the stacked structure includes the following steps: A hole transport material layer is formed on the side of the light-emitting layer away from the cathode. The material of the hole transport material layer includes the compound as described in claim 1 or 2, or the compound prepared by the preparation method as described in claim 3 or 4. Then, the hole transport material layer is treated with a first illumination condition to obtain a hole transport precursor layer. An anode is formed on the side of the hole transport precursor layer away from the light-emitting layer; The stacked structure containing the hole transport precursor layer and the anode is processed under a second illumination condition to obtain the hole transport layer.

11. The preparation method according to claim 9 or 10, characterized in that, The wavelength of light under the first illumination condition is 363 nm to 367 nm, and the wavelength of light under the second illumination condition is 252 nm to 256 nm.

12. A display device, characterized in that, The display device includes an electroluminescent device as described in any one of claims 5 to 8, or an electroluminescent device prepared by the preparation method described in any one of claims 9 to 11.

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