CN116234345A - Electroluminescence device, its manufacturing method, and display device - Google Patents

Abstract

The present application discloses an electroluminescent device, its preparation method, and a display device. The electroluminescent device is provided with a thermistor layer between the light-emitting layer and the electron transport layer, and the material of the thermistor layer includes The thermosensitive material with positive temperature coefficient resistance characteristics can improve the phenomenon that the conductivity of the electron transport layer increases due to the aging of electricity, balance the injection of electrons and holes, and improve the performance of the device; and the thermistor layer can follow the electron The change of the conductivity of the transmission layer realizes the dynamic change of the resistivity, so as to prevent the problem of the decline of the resistance performance of the resistance layer caused by the aging of the device.

Description

Electroluminescence device, its manufacturing method, and display device

technical field

The present application relates to the field of optoelectronic devices, in particular to an electroluminescence device, a preparation method thereof, and a display device.

Background technique

Electroluminescence, also known as electric field luminescence, is a physical phenomenon in which electrons excited by the electric field hit the luminescence center by applying a voltage to two electrodes to generate an electric field, which causes the transition, change, and recombination of electrons between energy levels to cause luminescence.

QLED (Quantum Dots Light-Emitting Diode, Quantum Dot Light-Emitting Diode) is a new type of electroluminescent device, and its basic structure is a sandwich structure composed of a hole transport layer, a light-emitting layer and an electron transport layer. This is a new technology between liquid crystal and OLED. The core technology of QLED is "Quantum Dot (quantum dot)". . This substance has a very special property: when the quantum dot is stimulated by light, it will emit colored light, and the color is determined by the material making up the quantum dot and its size and shape. Because it has this property, it is able to change the color of the light emitted by the light source. The emission wavelength range of quantum dots is very narrow, and the color is relatively pure and adjustable, so the picture of quantum dot display will be clearer and brighter than that of liquid crystal display.

However, during the aging process of QLED devices, there is often a problem of carrier injection imbalance, which affects the performance of the device.

application content

Embodiments of the present application provide an electroluminescence device, a manufacturing method thereof, and a display device, aiming at improving the performance of the device.

In the first aspect, the embodiment of the present application provides an electroluminescent device, including: including a cathode, an anode, and a light-emitting layer and an electron transport layer arranged between the cathode and the anode, and the light-emitting layer is close to the anode The electron transport layer is disposed close to the cathode, and a thermistor layer is also arranged between the light-emitting layer and the electron transport layer, and the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient. .

Optionally, the material of the thermistor layer further includes a first polymer.

Optionally, the thermosensitive material is selected from superconducting carbon black, and/or metal nanoparticles, and the metal nanoparticles are selected from at least one of silver, platinum or gold nanoparticles.

Optionally, the mass ratio of the superconducting carbon black to the first high molecular polymer is 1: (5-20); and/or, the ratio of the metal nanoparticles to the first high molecular polymer The mass ratio is 1: (10-20).

Optionally, the first polymer is selected from at least one of polyethylene, polycarbonate or polymethyl methacrylate, and/or,

The resistivity of the superconducting carbon black is 0.8Ω·m to 1.2Ω·m; and/or,

The particle size of the metal nanoparticles is 5nm to 8nm.

Optionally, the material of the thermistor layer is composed of the first polymer and superconducting carbon black, or the material of the thermistor layer is composed of the first polymer and metal nanoparticles composition.

Optionally, the material of the thermistor layer further includes a second high molecular polymer, and the second high molecular polymer is selected from at least one of polyvinyl alcohol or povidone.

Optionally, the mass ratio of the second high molecular polymer to the first high molecular polymer is 1:(5-10).

Optionally, the light-emitting layer is an organic light-emitting layer or a quantum dot light-emitting layer, and the material of the organic light-emitting layer is selected from diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, At least one of the TBPe fluorescent material that emits blue light, the TTPA fluorescent material that emits green light, the TBRb fluorescent material that emits orange light, and the DBP fluorescent material that emits red light; At least one of dots and core-shell quantum dots, the single-structure quantum dots are selected from at least one of II-VI group compounds, III-V group compounds, IV-VI group and I-III-VI group compounds , the II-VI group compound is selected from CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, CdTe, ZnTe, HgS, HgSe, HgTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, At least one of CdZnSeS, CdZnSeTe and CdZnSTe, the III-V group compound is selected from at least one of InP, InAs, GaP, GaAs, GaSb, InSb, AlAs, AlN, AlP, InAsP, InNP, InNSb, GaAlNP and InAlNP A kind; The group IV-VI compound is selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe One; the I-III-VI group compound is selected from at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ , and the core of the quantum dot with the core-shell structure is selected from any one of the single-structure quantum dots The shell material of the quantum dot of the core-shell structure is selected from at least one of CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS and ZnS; and/or,

The material of the electron transport layer is selected from: at least one of ZnO, TiO ₂ , MgO, Al ₂ O ₃ ; and/or,

The cathode material is selected from at least one of Ag electrodes, Al electrodes, Au electrodes, Pt electrodes or alloy electrodes; and/or,

The anode material is selected from a metal oxide electrode or a composite electrode, and the metal oxide electrode is selected from at least one of ITO, FTO, ATO, AZO, GZO, 1ZO, MZO and AMO, and the composite electrode is AZO/ Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS or ZnS/Al/ZnS.

Optionally, the thickness of the thermistor layer is 15nm to 25nm.

In a second aspect, the present application also provides a method for preparing an electroluminescent device, comprising the following steps:

Prepare a light-emitting layer on the anode;

preparing a thermistor layer on the light-emitting layer;

forming an electron transport layer on the thermistor layer; and

preparing a cathode on the electron transport layer to obtain the electroluminescent device;

Alternatively, an electron transport layer is prepared on the cathode;

preparing a thermistor layer on the electron transport layer;

preparing a light-emitting layer on the thermistor layer; and

preparing an anode on the light-emitting layer to obtain the electroluminescent device;

Wherein, the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient.

Optionally, the method for preparing the material of the thermistor layer includes: mixing and heating the first polymer and the thermosensitive material to obtain the material of the thermistor layer.

Optionally, the thermosensitive material is selected from at least one of superconducting carbon black or metal nanoparticles.

In a third aspect, the present application further provides a display device, comprising the electroluminescent device described in the first aspect, or comprising an electroluminescent device prepared by the preparation method described in the second aspect.

The present application provides a thermistor layer between the light-emitting layer and the electron transport layer. The material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient. During the power-on process of the QLED device, the aging of the electron transport layer will Heat is generated, so the resistance of the thermosensitive material becomes larger, which will improve the phenomenon that the conductivity of the electron transport layer increases due to aging, balance the injection of electrons and holes, and improve the performance of the device; and the thermistor layer can be The dynamic change of the resistivity is realized according to the change of the conductivity of the electron transport layer, and the problem of the decrease of the resistance performance of the resistance layer caused by the aging of the device is prevented.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings that need to be used in the description of the embodiments.

Figure 1 is a schematic structural view of a positive structure of an electroluminescent device provided in an embodiment of the present application;

Figure 2 is a schematic structural view of an inverse structure of an electroluminescent device provided in an embodiment of the present application;

3 is a flow chart of a method for preparing a positive structure of an electroluminescent device provided in an embodiment of the present application;

Fig. 4 is a flowchart of a method for preparing an inverse structure of an electroluminescent device provided in an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

Embodiments of the present application provide an electroluminescent device, a manufacturing method thereof, and a display device. Each will be described in detail below. It should be noted that the description sequence of the following embodiments is not intended to limit the preferred sequence of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the application; therefore, the described range should be regarded as The description has specifically disclosed all possible subranges as well as individual values within that range. Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

First, an embodiment of the present application provides an electroluminescent device, including: a cathode, an anode, and a light-emitting layer and an electron transport layer arranged between the cathode and the anode, the light-emitting layer is arranged close to the anode, The electron transport layer is disposed close to the cathode, and a thermistor layer is also provided between the light-emitting layer and the electron transport layer, and the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient, that is, When the temperature of the thermosensitive material rises, the resistivity of the thermosensitive material will increase.

In this application, a thermistor layer with a positive temperature coefficient is provided between the light-emitting layer and the electron transport layer. Therefore, during the power-on process of the QLED device, the aging of the electron transport layer generates heat, and the resistance of the thermosensitive material becomes larger, which will improve the electronic performance. The phenomenon that the conductivity of the transport layer increases due to aging (caused by light or electricity), balances the injection of electrons and holes, and improves the performance of the device; and the thermistor layer can change with the conductivity of the electron transport layer In order to realize the dynamic change of the resistivity, the problem of the decrease of the resistance performance of the resistance layer caused by the aging of the device is prevented.

In some embodiments, the material of the thermistor layer also includes a first high molecular polymer, which can improve the film-forming property of the thermistor layer, and the first high molecular polymer can have high transparency, high strength and high Molecular materials such as polyethylene, polycarbonate, polymethyl methacrylate, etc.

In some embodiments of the present application, the heat-sensitive material is selected from materials with a positive temperature coefficient, such as superconducting carbon black, and/or metal nanoparticles. These materials can effectively improve the conductivity and processability of polymer materials. When the superconducting carbon black, and/or, the metal nanoparticles and the first polymer are in an appropriate ratio, the heat-sensitive material has better stability, transparency and positive temperature coefficient resistance characteristics.

For example: when the thermistor layer includes superconducting carbon black and the first polymer, in some specific embodiments, the mass ratio of the superconducting carbon black to the first polymer is 1 : (5～20), if the content of superconducting carbon black is too low, the resistance variability of the thermistor layer with temperature changes will decrease, if the content of superconducting carbon black is too high, the transparency of the thermistor layer will decrease. Light is not good. It can be understood that the mass ratio of the superconducting carbon black to the first polymer can be any value within the range of 1: (5-20), for example: 1:5, 1:6, 1: 7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1: 20, etc., or other unlisted values within the range of 1: (5-20).

For another example, when the thermistor layer includes metal nanoparticles and a first polymer, in some specific embodiments, the mass ratio of the metal nanoparticles to the first polymer is 1: (10～20), if the content of metal nanoparticles is too low, the resistance variability of the thermistor layer with temperature changes will decrease, if the content of metal nanoparticles is too high, the light transmittance of the thermistor layer will not be good. It can be understood that the mass ratio of the metal nanoparticles to the first polymer can be any value within the range of 1:(10-20), for example: 1:10, 1:11, 1:12 . value.

In some embodiments, the superconducting carbon black and/or the metal nanoparticles are uniformly dispersed in the first polymer.

In order to further improve the film-forming properties and surface smoothness of the thermistor layer, in some embodiments, the material of the thermistor layer also includes a second polymer: ethylene-vinyl acetate copolymer (EVA) , at least one of polyvinyl alcohol (PVA) or povidone (PVP), different from the first high molecular material, the second high molecular material is to further improve the thermal sensitivity on the basis of the first high molecular polymer The film-forming substance of the resistance layer, these materials have the characteristics of good resilience, strong tensile strength, high toughness and softness, so adding this material will improve the film-forming property of the entire thermistor layer.

In some specific embodiments, the mass ratio of the EVA to the first high molecular polymer is 1: (5-10), and in this ratio, the film-forming property and smoothness of the thermistor layer are better . It can be understood that the mass ratio of the EVA to the first high molecular weight polymer can be any value within the range of 1: (5-10), for example: 1:5, 1:6, 1:7, 1 :8, 1:9, 1:10, etc., or other unlisted values within the range of 1: (5~10).

In some embodiments, the resistivity of the superconducting carbon black is 0.8Ω·m to 1.2Ω·m, within the range of resistivity, the resistance variability of the thermistor layer with temperature will be better . It can be understood that the resistivity of the superconducting carbon black can be any value within the range of 0.8Ω·m to 1.2Ω·m, such as 0.8Ω·m, 0.85Ω·m, 0.9Ω·m, 0.95Ω ·m, 1.0Ω·m, 1.05Ω·m, 1.1Ω·m, 1.15Ω·m, 1.2Ω·m, etc., or other unlisted values from 0.8Ω·m to 1.2Ω·m.

In some embodiments, the metal nanoparticles are selected from at least one of silver, platinum or gold nanoparticles. The particle diameter of the metal nanoparticles is 5nm to 8nm, within this particle diameter range, the resistance variability of the thermistor layer with temperature changes will be better. It can be understood that the particle size of the metal nanoparticles can be any value within the range of 5nm to 8nm, such as 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, etc., or 5nm to 8nm. Value not listed.

The electroluminescent device can be of a positive structure or an inverse structure. In a positive structure the anode is disposed on the substrate. In an inverted structure the cathode is arranged on the substrate. Whether it is a positive structure or an inverse structure, electronic functional layers such as an electron injection layer and a hole blocking layer can also be provided between the cathode and the light-emitting layer, and between the anode and the light-emitting layer can be A hole functional layer such as a hole transport layer, a hole injection layer, and an electron blocking layer is provided. For example:

Figure 1 shows a schematic diagram of a positive structure of the electroluminescent device described in the embodiment of the present application. As shown in Figure 1, the positive structure quantum dot device includes a substrate 110, a The anode 120 on the surface, the hole transport layer 130 on the surface of the anode 120, the light emitting layer 140 on the surface of the hole transport layer 130, the thermistor layer 150 on the surface of the light emitting layer 140, the The electron transport layer 160 on the surface of the thermistor layer 150 and the cathode 170 disposed on the surface of the electron transport layer 160 .

Fig. 2 shows a schematic diagram of an inverse structure of the quantum dot device described in the embodiment of the present application. As shown in Fig. 2 , the inversion structure quantum dot device includes a substrate 110, an The cathode 170, the electron transport layer 160 disposed on the surface of the cathode 170, the thermistor layer 150 disposed on the surface of the electron transport layer 160, the light-emitting layer 140 disposed on the surface of the thermistor layer 150, and the The hole transport layer 130 on the surface of the light emitting layer 140 and the anode 120 disposed on the surface of the hole transport layer 130 .

In each embodiment of the present application, the material of each functional layer is a common material in the field, for example:

The substrate can be a rigid substrate or a flexible substrate. Specific materials may include at least one of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyethersulfone kind.

The material of the anode can be: a metal oxide electrode or a composite electrode, the metal oxide electrode is selected from at least one of ITO, FTO, ATO, AZO, GZO, 1ZO, MZO and AMO, and the composite electrode is AZO/ Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS or ZnS/Al/ZnS.

The hole injection layer material can be: poly(ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS), poly(9,9-dioctyl-fluorene-co-N-(4-butyl phenyl)-diphenylamine) (TFB), polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methyl oxyphenyl)-benzidine (TPD), 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4',4"-tri[ Phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis [(Di-4-tolylamino)phenylcyclohexane (TAPC), 4,4',4"-tris(diphenyl amino) triphenylamine (TDATA), p-doped phthalocyanine (for example, F4-TCNQ-doped zinc phthalocyanine (ZnPc)), F4-TCNQ-doped N,N′-diphenyl-N, N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine (α-NPD), hexaazatriphenylene-capronitrile (HAT-CN); or any of the above One or more combinations.

The material of the hole transport layer can be: arylamine, such as 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), N,N'-diphenyl-N,N' -Bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine (α-NPD), N,N'-diphenyl-N,N'-bis(3-methyl Phenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl )-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4, 4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), poly[(9,9'- Dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))](TFB) and poly(4-butylphenyl -diphenylamine) (poly-TPD); polyaniline; polypyrrole; poly(p)phenylene vinylene and its derivatives, such as poly(phenylene vinylene) (PPV), poly[2 -Methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV) and poly[2-methoxy-5-(3',7' -dimethyloctyloxy)-1,4-phenylenevinylene] (MOMO-PPV); copper phthalocyanine; aromatic tertiary amine or polynuclear aromatic tertiary amine; 4,4'-bis(p-carbazole base)-1,1'-biphenyl compounds; N,N,N',N'-tetraarylbenzidine; PEDOT:PSS and its derivatives; poly(N-vinylcarbazole) (PVK) and its Derivatives; polymethacrylate and its derivatives; poly(9,9-octylfluorene) and its derivatives; poly(spirofluorene) and its derivatives; N,N'-di(naphthalene-1-yl )-N,N'-diphenylbenzidine (NPB); spiro NPB; or a combination of any one or more of the above.

The light-emitting layer is an organic light-emitting layer or a quantum dot light-emitting layer, and the material of the organic light-emitting layer is selected from but not limited to diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, At least one of the TBPe fluorescent material that emits blue light, the TTPA fluorescent material that emits green light, the TBRb fluorescent material that emits orange light, and the DBP fluorescent material that emits red light; the material of the quantum dot light-emitting layer can be selected from but not limited to At least one of single-structure quantum dots and core-shell quantum dots. The single-structure quantum dots include single-component quantum dots or alloy structure quantum dots, and the single-component quantum dots can be selected from but not limited to at least one of II-VI group compounds, III-V group compounds and IV-VI group A sort of. As an example, the II-VI group compound can be selected from but not limited to at least one of CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, CdTe, ZnTe, HgS, HgSe, HgTe; the III-V group compound Can be selected from but not limited to at least one of InP, InAs, GaP, GaAs, GaSb, InSb, AlAs, AlN and AlP; or at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe of IV-VI group kind.

The quantum dots of the alloy structure are selected from but not limited to at least one of II-VI, III-V, IV-VI or I-III-VI compounds. As an example, the quantum dots of the alloy structure Points can be selected from the group II-VI: CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe; or III- Group V: InAsP, InNP, InNSb, GaAlNP, InAlNP, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNAs, InPAs, InPSb, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNAs, InAlNSb, InAlPAs, InAlPSb; or IV-VI group: at least one of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe species; the I-III-VI compound may be selected from but not limited to at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ .

The core of the quantum dot of the core-shell structure can be selected from any one of the above-mentioned single-structure quantum dots, and the shell material of the quantum dot of the core-shell structure can be selected from but not limited to CdS, CdTe, CdSeTe, CdZnSe, At least one of CdZnS, CdSeS, ZnSe, ZnSeS, and ZnS. As an example, the quantum dots of the core-shell structure can be selected from but not limited to CdZnSe/CdZnS/ZnS, CdZnSe/ZnSe/ZnS, CdSe/ZnS, CdTe/CdS, CdS/ZnS, CdTe/ZnS, InP/ZnS, CdSe At least one of /ZnSe/ZnS, ZnSe/ZnS, ZnSeTe/ZnS, CdSe/CdZnSeS/ZnS, InP/ZnSe/ZnS, and InP/ZnSeS/ZnS.

Electron transport materials may consist of inorganic materials and/or organic materials. When it is an inorganic material, it can be: undoped or with aluminum (Al), magnesium (Mg), indium (In), lithium (Li), gallium (Ga), cadmium (Cd), cesium (Cs) or copper (Cu) doped metal/non-metal oxides (e.g. TiO ₂ , ZnO, ZrO, SnO ₂ , WO ₃ , Ta ₂ O ₃ , HfO ₃ , Al ₂ O ₃ , ZrSiO ₄ , BaTiO ₃ and BaZrO ₃ ) . When it is an organic material, such as oxazole compound, isoxazole compound, triazole compound, isothiazole compound, oxadiazole compound, thiadiazole compound, perylene compound or aluminum complex and other organic materials. It should be noted that, in the embodiment of the present application, especially when the electron transport material is selected from metal oxides such as zinc oxide, titanium dioxide, magnesium oxide, aluminum oxide, etc., due to the obvious electron mobility of these materials in the aging process of the device Therefore, compared with other materials, the thermistor layer has a more significant effect of balancing the injection of electrons and holes and improving the performance of the device when metal oxide is selected as the electron transport material.

The cathode material may be at least one of Ag electrode, Al electrode, Au electrode, Pt electrode or alloy electrode.

The thickness of the anode is 20nm-200nm (nanometer); the thickness of the hole injection layer is 20nm-200nm; the thickness of the hole transport layer is 30nm-180nm; the total thickness of the light-emitting layer is 30nm-180nm. The thickness of the electron transport layer is 10nm-180nm; the thickness of the thermistor layer is 15nm-25nm; the thickness of the cathode is 40nm-190nm.

The present application also provides a method for preparing an electroluminescent device. FIG. 3 shows a method for preparing a positive structure of the electroluminescent device described in the embodiment of the present application. As shown in FIG. 3 , the electroluminescent device of the positive The preparation method of luminescent device comprises the following steps:

S10. preparing a light-emitting layer on the anode substrate;

S20. preparing a thermistor layer on the light-emitting layer;

S30. preparing an electron transport layer on the thermistor layer; and

S40. Prepare a cathode on the electron transport layer to obtain the electroluminescence device.

Wherein, the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient.

Fig. 4 shows the preparation method of a kind of inversion structure of the electroluminescence device described in the embodiment of the present application, as shown in Fig. 4, the preparation method of the electroluminescence device of inversion structure comprises the following steps:

S100. preparing an electron transport layer on the cathode substrate;

S200. preparing a thermistor layer on the electron transport layer;

S300. Prepare a light-emitting layer on the thermistor layer; and

S400. Prepare an anode on the light-emitting layer to obtain the electroluminescent device;

Wherein, the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient.

In some embodiments, the method for preparing the material of the thermistor layer includes: mixing and heating the first polymer and the thermosensitive material to obtain the material of the thermistor layer.

In some embodiments, the thermosensitive material is at least one selected from superconducting carbon black or metal nanoparticles.

In order to ensure that the first polymer and the heat-sensitive material are fully mixed, in some embodiments, the heating temperature is 100°C to 120°C, and/or, the mixing time is greater than 12 hours, if If the mixing time is too short or the temperature is too low, the mixing will be uneven; if the temperature is too high, it will affect the stability of the heat-sensitive material or the first polymer structure. It can be understood that the heating temperature can be Any value within the range of 100°C to 120°C, for example: 100°C, 102°C, 105°C, 108°C, 110°C, 112°C, 115°C, 118°C, 120°C, etc., or within the range of 100°C to 120°C Other values not listed.

Based on the same idea, the present application also provides a display device, including the electroluminescent device described in any one of the above, or the electroluminescent device prepared by the preparation method described in any one of the above, its structure, realization principle and The effects are similar and will not be repeated here. In a specific embodiment, the display device is a QLED.

Optionally, the display device may be: a lighting fixture and a backlight, or any product or component with a display function such as a mobile phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, and a navigator.

It should be noted that the drawings of the embodiments of the present invention only relate to the structures involved in the embodiments of the present application, and other structures may refer to common designs.

In addition, in order to better understand the present application, the present application also provides the following specific examples.

Example 1:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) The hole injection layer is spin-coated on the 80nm thick ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat a luminescent layer on the hole transport layer, the material of the luminescent layer is CdZnSe, and the thickness is 25nm.

(4) Spin-coat a thermistor layer on the light-emitting layer, the thickness of the thermistor layer is 20nm, and it is composed of polycarbonate and superconducting carbon black, and the mass ratio of superconducting carbon black to polycarbonate is 1:5 .

The preparation process of the thermistor layer is as follows: polycarbonate and superconducting carbon black are dissolved in DMF solvent, and the final concentration of the thermistor material solution is 10 mg/mL, and the thermistor is spin-coated. The solution of the resistive material is spun on the light-emitting layer, and heated at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescence device.

Example 2:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) Spin-coat the hole transport layer on the hole injection layer, the specific material is TFB, and the thickness is 25nm;

(3) Spin-coat the luminescent layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm;

(4) Spin-coat a thermistor layer on the luminescent layer, the thickness of this layer is 20nm, it is composed of polycarbonate and superconducting carbon black, and the mass ratio of superconducting carbon black and polycarbonate is 1:8.

The preparation process of the thermistor layer is as follows: dissolving polycarbonate and superconducting carbon black in DMF solvent, and finally forming a thermistor material solution with a concentration of 10 mg/mL; The solution of the thermistor material was spun on the light-emitting layer, and heated at 120° C. for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescent device.

Example 3:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the luminescent layer, the thickness of this layer is 20nm, it is composed of polycarbonate and superconducting carbon black, and the mass ratio of superconducting carbon black and polycarbonate is 1:20.

The preparation process of the thermistor layer is as follows: polycarbonate and superconducting carbon black are dissolved in DMF solvent to form a thermistor material solution with a final concentration of 10mg/mL, and the solution is spin-coated on On the light-emitting layer, heat at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporating Ag electrodes with a thickness of 100 nm, and finally packaging to form an electroluminescence device.

Example 4:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the light-emitting layer, the thickness of this layer is 20nm, it is made of polycarbonate, superconducting carbon black and EVA, and the mass ratio of superconducting carbon black and polycarbonate is 1:8, The mass ratio of EVA to polycarbonate is 1:5.

The preparation process of the thermistor layer is as follows: dissolving superconducting carbon black, polycarbonate and EVA in DMF solvent to form a thermistor material solution with a final concentration of 10 mg/mL, and spin coating the solution Spin-coat on the light-emitting layer, and heat at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescence device.

Example 5:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the light-emitting layer, the thickness of this layer is 20nm, it is made of polycarbonate, superconducting carbon black and EVA, and the mass ratio of superconducting carbon black and polycarbonate is 1:8, The mass ratio of EVA to polycarbonate is 3:20.

The preparation process of the thermistor layer is as follows: dissolving superconducting carbon black, polycarbonate and EVA in DMF solvent to form a thermistor material solution with a final concentration of 10 mg/mL. Spin the solution on the light-emitting layer and heat it at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescent device.

Embodiment 6:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the light-emitting layer, the thickness of this layer is 20nm, it is made of polycarbonate, superconducting carbon black and EVA, and the mass ratio of superconducting carbon black and polycarbonate is 1:8, The mass ratio of EVA to polycarbonate is 1:10.

The preparation process of the thermistor layer is as follows: dissolving superconducting carbon black, polycarbonate and EVA in DMF solvent to form a thermistor material solution with a final concentration of 10 mg/mL. Spin the solution on the light-emitting layer and heat it at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescent device.

Embodiment 7:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat a thermistor layer on the luminescent layer, the thickness of this layer is 20nm, and it is composed of polycarbonate and Ag metal nanoparticles, and the mass ratio of Ag metal nanoparticles to polycarbonate is 1:10.

The preparation process of the thermistor layer is as follows: dissolving Ag metal nanoparticles and polycarbonate in DMF solvent to form a final thermistor material solution with a concentration of 10 mg/mL, and spin coating The solution was spun on the light-emitting layer, and heated at 120°C for 30 minutes to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescence device.

Embodiment 8:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the light-emitting layer. The thickness of the layer is 20nm, and it is composed of polycarbonate and Ag metal nanoparticles. The mass ratio of Ag metal nanoparticles to polycarbonate is 3:40, two kinds The substance is dissolved in DMF solvent, and the final composition concentration is 10mg/mL of thermistor material solution. The solution is spin-coated on the light-emitting layer, and heated at 120°C for 30min to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescence device.

Embodiment 9:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on 80nm ITO, the specific material is PEDOT:PSS, and the thickness is 20nm.

(2) A hole transport layer is spin-coated on the hole injection layer, the specific material is TFB, and the thickness is 25 nm.

(3) Spin-coat the light-emitting layer on the hole transport layer, the specific material is CdZnSe, and the thickness is 25nm.

(4) Spin-coat the thermistor layer on the light-emitting layer. The thickness of this layer is 20nm. It is composed of polycarbonate and Ag metal nanoparticles. The mass ratio of Ag metal nanoparticles to polycarbonate is 1:20. Two kinds of The substance was dissolved in DMF solvent to form a thermistor material solution with a final concentration of 10mg/mL. The solution was spin-coated on the light-emitting layer, and heated at 120°C for 30min to fully form a film.

(5) An electron transport layer is spin-coated on the thermistor layer, the specific material is ZnO, and the thickness is 30nm.

(6) Evaporate an Ag electrode with a thickness of 100 nm. Finally, it is packaged to form an electroluminescence device.

Comparative example 1:

This embodiment provides a positive bottom emission electroluminescent device, and the preparation method of the device comprises the following steps:

(1) A hole injection layer is spin-coated on ITO.

(2) A hole transport layer is spin-coated on the hole injection layer.

(3) Spin-coat the light-emitting layer on the hole transport layer.

(4) An electron transport layer is spin-coated on the light-emitting layer.

(5) Evaporating Ag electrodes, and finally packaging to form an electroluminescent device.

Verification example

In this verification example, the performance of the electroluminescent device provided in each embodiment and comparative example is evaluated by testing the maximum EQE of the device, the actual measurement time of T95, and the lifetime of T95-1K. The test results are shown in Table 1.

Table 1

Note: EQE is the external quantum efficiency; T95 means the time taken for the brightness of the device to decay from 100% to 95%; T95-1K means the time taken for the brightness of the device to decay from 100% to 95% when the brightness of the device is 1000nit.

It can be seen from Table 1 that after the thermistor layer is added to the electroluminescent device, the performance of T95-1K, EQE and T95 of the device is significantly improved. This is because the thermistor layer generates heat with the electron transport layer, and the resistance changes. Large, which in turn balances the injection of electrons and holes. In addition, comparing Examples 4 to 6 with other examples, it can be seen that after adding ethylene-vinyl acetate copolymer in the thermistor layer, the performance of balancing electron and hole injection is better, so it is shown as T95- The performance of 1K, EQE and T95 showed better results, which is that ethylene-vinyl acetate copolymer can improve the film formation and surface smoothness of the thermistor layer, so that the thermistor layer has better resistance caused by variability.

To sum up, the present application provides an electroluminescent device and its preparation method, and a display device. A thermistor layer is provided between the light-emitting layer and the electron transport layer. The material of the thermistor layer includes a thermosensitive Material, the heat-sensitive material has a resistance characteristic of a positive temperature coefficient, and the resistance of the heat-sensitive material increases with the heat generated by the aging of the electron transport layer during the electrification process of the QLED device, thereby improving the electrical conductivity of the electron transport layer due to aging The rising phenomenon balances the injection of electrons and holes, and improves the performance of the device; and the thermistor layer can realize the dynamic change of resistivity with the change of the conductivity of the electron transport layer, preventing the aging of the device. The problem that the resistance performance of the resistance layer decreases. In addition, the method provided by this embodiment is simple to operate, low in cost and good in repeatability, and has broad application prospects in the field of optoelectronic display.

The electroluminescence device provided by the embodiment of the present application, its preparation method, and display device have been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present application. The description of the above embodiment is only It is used to help understand the method and its core idea of this application; at the same time, for those skilled in the art, according to the idea of this application, there will be changes in the specific implementation and application scope. In summary, this specification The content should not be construed as a limitation of the application.

Claims (14)

1. An electroluminescent device, characterized in that it comprises: a cathode, an anode, and a light-emitting layer and an electron transport layer arranged between the cathode and the anode, the light-emitting layer is arranged near the anode, the The electron transport layer is disposed close to the cathode, and a thermistor layer is further disposed between the light-emitting layer and the electron transport layer, and the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient. 2. The electroluminescence device according to claim 1, wherein the material of the thermistor layer further comprises a first polymer. 3. The electroluminescent device according to claim 2, wherein the thermosensitive material is selected from superconducting carbon black, and/or metal nanoparticles, wherein the metal nanoparticles are selected from silver, platinum or at least one of gold nanoparticles. 4. The electroluminescence device according to claim 3, characterized in that, the mass ratio of the superconducting carbon black to the first high molecular polymer is 1: (5-20); and/or, the The mass ratio of the metal nanoparticles to the first polymer is 1:(10-20). 5. The electroluminescent device according to claim 3, wherein the first polymer is selected from at least one of polyethylene, polycarbonate or polymethyl methacrylate, and/or , The resistivity of the superconducting carbon black is 0.8Ω·m to 1.2Ω·m; and/or, The particle size of the metal nanoparticles is 5nm to 8nm. 6. The electroluminescence device according to claim 3, characterized in that, the material of the thermistor layer is made up of the first polymer and superconducting carbon black, or the material of the thermistor layer The material is composed of the first polymer and metal nanoparticles. 7. The electroluminescent device according to claim 2, characterized in that, the material of the thermistor layer also includes a second high molecular polymer, and the second high molecular polymer is selected from the group consisting of ethylene-vinyl acetate copolymer At least one of substance, polyvinyl alcohol or povidone. 8 . The electroluminescent device according to claim 7 , wherein the mass ratio of the second high molecular polymer to the first high molecular polymer is 1:(5˜10). 9. The electroluminescent device according to claim 1, wherein the light-emitting layer is an organic light-emitting layer or a quantum dot light-emitting layer, and the material of the organic light-emitting layer is selected from diaryl anthracene derivatives, diphenyl At least one of vinyl aromatic derivatives, pyrene derivatives or fluorene derivatives, blue-emitting TBPe fluorescent materials, green-emitting TTPA fluorescent materials, orange-emitting TBRb fluorescent materials, and red-emitting DBP fluorescent materials The material of the quantum dot light-emitting layer is selected from at least one of single-structure quantum dots and core-shell structure quantum dots, and the single-structure quantum dots are selected from II-VI group compounds, III-V group compounds, IV-VI At least one of group and I-III-VI group compound, the II-VI group compound is selected from CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, CdTe, ZnTe, HgS, HgSe, HgTe, CdZnS, CdZnSe, At least one of CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe and CdZnSTe, the III-V group compound is selected from InP, InAs, GaP, GaAs, GaSb, InSb, AlAs, AlN, At least one of AlP, InAsP, InNP, InNSb, GaAlNP and InAlNP; the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, At least one of SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the I-III-VI group compound is selected from at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ , and the quantum dots of the core-shell structure The core is selected from any one of the single-structure quantum dots, and the shell material of the quantum dots with the core-shell structure is selected from at least one of CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS and ZnS a; and/or, The material of the electron transport layer is selected from: at least one of ZnO, TiO ₂ , MgO, Al ₂ O ₃ ; and/or, The cathode material is selected from at least one of Ag electrodes, Al electrodes, Au electrodes, Pt electrodes or alloy electrodes; and/or, The anode material is selected from a metal oxide electrode or a composite electrode, and the metal oxide electrode is selected from at least one of ITO, FTO, ATO, AZO, GZO, 1ZO, MZO and AMO, and the composite electrode is AZO/ Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS or ZnS/Al/ZnS. 10. The electroluminescence device according to claim 1, wherein the thickness of the thermistor layer is 15nm to 25nm. 11. A method for preparing an electroluminescent device, comprising the steps of: Prepare a light-emitting layer on the anode; preparing a thermistor layer on the light-emitting layer; forming an electron transport layer on the thermistor layer; and preparing a cathode on the electron transport layer to obtain the electroluminescent device; Alternatively, an electron transport layer is prepared on the cathode; preparing a thermistor layer on the electron transport layer; preparing a light-emitting layer on the thermistor layer; and preparing an anode on the light-emitting layer to obtain the electroluminescent device; Wherein, the material of the thermistor layer includes a thermosensitive material with a positive temperature coefficient. 12. The preparation method of the electroluminescent device according to claim 11, characterized in that, the preparation method of the material of the thermistor layer comprises: mixing and heating the first high molecular polymer and the thermosensitive material to obtain The material of the thermistor layer. 13 . The method for preparing an electroluminescent device according to claim 11 , wherein the heat-sensitive material is at least one selected from superconducting carbon black or metal nanoparticles. 14 . 14. A display device, characterized in that it comprises the electroluminescent device according to any one of claims 1 to 10, or comprises an electroluminescent device prepared by the preparation method according to any one of claims 11 to 13 .

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