CN115568239A - QLED device and preparation method thereof - Google Patents
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Abstract
The invention discloses a QLED device and a preparation method of the QLED device. The QLED device comprises an anode, a light-emitting layer, an electron transport layer and a cathode which are arranged in a laminated manner, wherein at least one of the materials of the light-emitting layer and the electron transport layer comprises an antioxidant. The antioxidant can prevent the quantum efficiency of the quantum dots from being reduced, and can also prevent oxygen radicals from being adsorbed on the surface of a material to influence the efficiency of a device. The QLED device and the preparation method of the QLED device provided by the invention can effectively prevent the oxide from damaging the device and prolong the service life of the device.
Description
Technical Field
The invention relates to the field of photoelectric devices, in particular to a QLED device and a preparation method of the QLED device.
Background
Quantum Dots (Quantum Dots) are nanocrystals with a radius smaller or close to the exciton Bohr radius, typically with a particle size between 1 and 20nm. The quantum dot has a plurality of unique nanometer properties due to the obvious quantum confinement effect: the luminescent wavelength can be adjusted by controlling the particle size, the spectral line width is narrow, the absorption spectrum is wide, the color purity is high, the electron mobility is high, the light stability is good, the biocompatibility is good, the flexible display device can be used for flexible display and the like, and the flexible display device is widely applied to the fields of luminescent display, photovoltaic solar energy, biological markers and the like.
From 1994, the first Quantum dot light-emitting diodes (QLEDs) were prepared, and through the development of more than 20 years, the mechanisms of material synthesis, device preparation and light emission were greatly improved. However, whether there is a considerable gap between the basic device performance parameters, such as device efficiency and device operational stability, the lifetime of the device has been the most critical issue limiting its commercial application, where the stability of the light-emitting layer and the electron-transporting layer is also a critical factor affecting lifetime.
Therefore, it is necessary to provide a QLED device and a method for manufacturing the QLED device to solve the above problems.
Disclosure of Invention
The invention aims to provide a QLED device and a preparation method of the QLED device, so as to improve the efficiency of the QLED device.
In order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows:
the invention provides a QLED device, which comprises an anode, a light-emitting layer, an electron transport layer and a cathode which are arranged in a laminated manner, wherein at least one of the materials of the light-emitting layer and the electron transport layer comprises an antioxidant.
Optionally, the antioxidant is selected from one or more of dibutyl hydroxy toluene, antioxidant 1010, antioxidant 1076, antioxidant 168, vitamin C, vitamin A, vitamin E, tea polyphenols, ethoxyquinoline, ethoxyquin, butyl hydroxy anisole, tert-butyl hydroquinone, propyl gallate.
Optionally, the molar fraction of the antioxidant in the light emitting layer or the electron transport layer is in the range of 0.1% to 20%.
Optionally, the material of the light emitting layer further comprises quantum dots selected from one or more of quantum dots of a group II-VI compound semiconductor, quantum dots of a group III-V compound semiconductor, quantum dots of a group I-III-VI compound semiconductor, perovskite quantum dots.
Optionally, the quantum dot is a core-shell quantum dot.
Optionally, the material of the electron transport layer further comprises an inorganic oxide semiconductor selected from ZnO and SnO 2 、TiO 2 One or more of Mg or Al doped ZnO.
Optionally, the material of the light emitting layer consists of an antioxidant and quantum dots; or the material of the electron transport layer consists of an antioxidant and an inorganic oxide semiconductor
Correspondingly, the preparation method of the QLED device is characterized by comprising the following steps:
respectively providing a luminescent layer material solution and an electron transport layer material solution;
depositing the luminescent layer material solution on an anode substrate to form the luminescent layer;
depositing the electron transport layer material solution on the light emitting layer to form the electron transport layer;
or depositing the electron transport layer material solution on a cathode substrate to form the electron transport layer;
depositing the luminescent layer material solution on the electron transport layer to form the luminescent layer;
wherein at least one of the luminescent layer material solution and the electron transport layer material solution includes an antioxidant.
Optionally, the luminescent layer material solution further comprises quantum dots dispersed in an alkane organic reagent; the solution of the electron transport layer material further comprises an inorganic oxide semiconductor dispersed in an alcohol organic reagent.
Optionally, the mass fraction of the antioxidant is 1% to 50% based on the total mass of the quantum dots dispersed in the alkane organic reagent or the inorganic oxide semiconductor dispersed in the alcohol organic reagent.
Optionally, the concentration of the quantum dots is 10-40 mg/mL.
Has the advantages that:
the QLED device provided by the invention comprises a cathode, an electron transport layer, a quantum dot light-emitting layer and an anode which are sequentially stacked, wherein at least one of the electron transport layer and the quantum dot light-emitting layer comprises an antioxidant. The antioxidant can prevent the reduction of quantum efficiency of the quantum dots, can prevent oxygen radicals from being adsorbed on the surface of a material to influence the efficiency of a device, and can effectively improve the performance and prolong the service life of the device. In the preparation method, on the basis of the existing preparation method of the QLED device, the antioxidant is added into the material solution of the electron transmission layer or the quantum dot light-emitting layer, and the corresponding lamination can be obtained through deposition in various ways. The preparation process is simple and controllable, and is favorable for large-scale production and application.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an inverted-structure QLED device provided in embodiment 1 of the present application;
description of the drawings:
a substrate 110; a cathode 120; an electron transport layer 130; a luminescent layer 140; a hole transport layer 150; a hole injection layer 160; and an anode 170.
Detailed Description
In order to make the technical problems, technical solutions and technical effects to be solved by the present invention more clearly and clearly understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the application provides a QLED device and a preparation method of the QLED device. The following are detailed below. It should be noted that the following description of the embodiments is not intended to limit the preferred order 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 invention may exist in a range of forms; it is to be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention; accordingly, the described range descriptions should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, it is contemplated that the description of a range from 1 to 6 has specifically disclosed sub-ranges such as, for example, 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., as well as individual numbers within a range such as, for example, 1, 2,3, 4,5, and 6, as applicable regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any number (fractional or integer) recited within the indicated range.
The invention provides a QLED device which comprises an anode, a light-emitting layer, an electron transport layer and a cathode which are arranged in a laminated manner, wherein at least one of the materials of the light-emitting layer and the electron transport layer comprises an antioxidant. The antioxidant can prevent oxygen or oxygen free radicals in air from damaging the material of the light-emitting layer or the electron transport layer. The oxidation resistance of the QLED device is improved, and the service life of the device is prolonged.
Optionally, the antioxidant is one or more of dibutylhydroxytoluene (BHT), antioxidant 1010 (Irganox 1010), antioxidant 1076 (Irganox 1076), antioxidant 168 (Irgafos 168), vitamin C, vitamin a, vitamin E, tea polyphenols, ethoxyquinoline, ethoxyquin (EMQ), butylhydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), or Propyl Gallate (PG).
The mole fraction of the antioxidant in the light emitting layer and/or the electron transport layer ranges from 0.1% to 20%. Within the range, the light-emitting layer and the electron transport layer can be ensured to have oxidation resistance, and the addition of the antioxidant can be ensured not to influence the performance of the light-emitting layer and the electron transport layer.
The material of the light-emitting layer further includes quantum dots selected from one or more of quantum dots of a group II-VI compound semiconductor, quantum dots of a group III-V compound semiconductor, quantum dots of a group I-III-VI compound semiconductor, or perovskite quantum dots. Group II elements include, but are not limited to, zn, cd, hg, and the like; group VI elements include, but are not limited to, O, S, se, te, po, lv, and the like; group III elements include, but are not limited to, ga, in, pb, and the like; group V elements include, but are not limited to, as, P, and the like. Optionally, the quantum dot is a core-shell structure quantum dot. By coating an organic or inorganic shell layer, the fluorescence property of the quantum dot can be effectively improved, the quantum efficiency is improved, and the photoelectric effect is enhanced.
Optionally, the material of the electron transport layer further comprises an inorganic oxide semiconductor, and the inorganic oxide semiconductor is ZnO or SnO 2 、TiO 2 And one or more of Mg or Al doped ZnO.
The QLED device may be in a positive structure or an inverted structure, and preferably, the QLED device further includes a substrate, the anode is disposed on the substrate or the cathode is disposed on the substrate, the material selection of the substrate is not specifically limited, and a rigid substrate or a flexible substrate may be adopted, the rigid substrate includes but is not limited to a glass plate, and the flexible substrate includes but is not limited to a PET substrate.
To better understand the present solution, a bottom-emitting QLED device is provided, wherein the anode or cathode material disposed on the substrate is a transparent material, such as a doped metal oxide, including but not limited to one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), aluminum-doped magnesium oxide (AMO), or a composite electrode sandwiching a metal between doped or undoped transparent metal oxides, including but not limited to AZO/Ag/o, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, znO/Ag/ZnO, znO/Al/ZnO, tiO/Al/ITO, znO/Ag/ZnO, znO/Al/ZnO, tiO 2 /Ag/TiO 2 、TiO 2 /Al/TiO 2 One or more of ZnS/Ag/ZnS, znS/Al/ZnS.
For a better understanding of the present solution, there is also provided a top-emitting QLED device, wherein the anode or cathode material disposed on the substrate is an opaque material, such as a metal or alloy, including but not limited to Ag, al, au.
The QLED device provided by the invention can further comprise a hole functional layer, wherein the hole functional layer is arranged between the anode and the light-emitting layer and comprises at least one of a hole transport layer and a hole injection layer. The arrangement of the hole functional layer can effectively improve the charge transport function.
The material of the hole transport layer is C 38 H 28 N 2 I.e. 4,4 '-bis (9H-carbazol-9-yl) -2,2' -dimethylbiphenyl, commonly abbreviated CDBP; c 36 H 24 N 2 I.e. 4,4'-N, N' -dicarbazolbiphenyl, commonly referred to by the abbreviation CBP; c 15 H 16 N 2 O 2 I.e. N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine, commonly referred to by the abbreviation NPB; c 54 H 36 N 4 I.e., tris (4- (9 carbazolyl) phenyl) amine, is commonly referred to by one or more of the abbreviations TCTA.
The material of the hole injection layer 160 is 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), molybdenum trioxide (MoO) 3 ) Tungsten trioxide (WO) 3 ) Vanadium pentoxide (V) 2 O 5 ) And tantalum pentoxide (Ta) 2 O 5 ) One or more of (a). The hole injection layer can improve the hole injection efficiency and the mobility, balance the mobility between holes and electrons, and greatly increase the probability of radiation recombination of current carriers, thereby improving the brightness and the luminous efficiency of the QLED.
Accordingly, for better understanding of the present solution, there is provided a method for manufacturing a QLED device with a front structure, comprising:
step S110: respectively providing a luminescent layer material solution and an electron transport layer material solution;
step S210: depositing a luminescent layer material solution on the anode substrate to form a luminescent layer;
step S310: depositing an electron transport layer material solution on the light emitting layer to form an electron transport layer;
or, a method for preparing an inverted structure QLED device is provided, which includes:
step S120: respectively providing a luminescent layer material solution and an electron transport layer material solution;
step S220: forming an electron transport layer on the cathode substrate from the electron transport layer material solution;
step S320: depositing a luminescent layer material solution on the electron transport layer to form a luminescent layer;
wherein at least one of the light-emitting layer material solution and the electron transport layer material solution includes an antioxidant. The antioxidant is added into the luminescent layer material solution to prevent the quantum efficiency of the quantum dots from being reduced, and the antioxidant is added into the electron transport layer material solution to prevent oxygen radicals from being adsorbed on the surface of an inorganic oxide semiconductor such as ZnO and the like to influence the efficiency of a device. The antioxidant can improve the stability of the solution of the electron transport layer or the light-emitting layer material, thereby improving the performance and the service life of the device.
The luminescent layer material solution also comprises quantum dots dispersed in the alkane organic reagent; the solution of the electron transport layer material further includes an inorganic oxide semiconductor dispersed in the alcoholic organic reagent. The quantum dots are used as the luminescent layer material, the prepared QLED device has good light stability, and compared with the traditional fluorescent powder, the color gamut of the display device can be greatly improved.
The concentration of the quantum dots dispersed in the alkane organic reagent is 5mg/mL to 60mg/mL, preferably 10mg/mL to 40mg/mL. The solvent in the quantum dot solution may be, for example, n-octane, which is configured by dissolving the quantum dots in n-octane. If the concentration of the solution is too low, the quantum dot light-emitting layer in the device is too thin, the brightness of the device is weak, and if the concentration of the solution is too high, the quantum dot light-emitting layer is too thick, the internal resistance of the device is increased, and the performance of the device is not favorably improved. Preferably, the particle size of the quantum dots is preferably in the range of 8 to 15 nanometers (nm), such as 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, and the like. If the particle size of the quantum dot is too small, the film forming property of the quantum dot material is poor, the energy resonance transfer effect among quantum dot particles is obvious, the application of the material is not facilitated, and if the particle size of the quantum dot is too large, the quantum effect of the quantum dot material is weakened, so that the photoelectric property of the material is reduced. The thickness of the formed quantum dot light-emitting layer is 5-50nm.
The concentration of the inorganic oxide semiconductor dispersed in the alcohol organic reagent is 10mg/mL to 50mg/mL. If the concentration of the electron transport material is too low, the electron transport layer in the photoelectric device is too thin, and if the concentration of the electron transport material is too high, the electron transport layer is too thick, and the electron transport layer 130 is too thin and too thick, both of which cause imbalance between electrons and holes in the device, and further cause poor performance of the device. The thickness of the formed electron transport layer is 5-100nm.
The mass fraction of the antioxidant is 1% to 50% based on the total mass of the quantum dots dispersed in the alkane organic agent or the inorganic oxide semiconductor dispersed in the alcohol organic agent, and preferably, the mass fraction of the antioxidant is 5% to 20%. Within the range, the solution of the luminescent layer material and the solution of the electron transport layer material can fully realize the improvement of the oxidation resistance, the stability after film formation is also improved, the influence on the luminescent performance of the luminescent layer and the transport performance of the electron transport layer can be ignored, and the service life of the QLED device prepared from the solutions can be effectively prolonged.
Optionally, the deposition is selected from one of spin coating, ink jet printing, and doctor blading. For better understanding of the present solution, a specific operation of step S210 or step S220 is provided herein, which includes: placing the ITO substrate in a glove box, and spin-coating the prepared luminescent layer or electron transport layer material solution to form a film; the film thickness is controlled by adjusting the concentration of the solution, the spin-coating speed and the spin-coating time, and then the thermal annealing treatment is carried out at a proper temperature, so that the spin-coating method has the characteristics of mild process conditions, simplicity in operation, energy conservation, environmental friendliness and the like in the aspect of photoelectric device preparation, and the prepared photoelectric device has the advantages of high carrier mobility, accurate thickness and the like. At present, the spin coating method is the most commonly used method for preparing the quantum dot light emitting diode.
The spin coating speed may be 1000rpm to 6000rpm, and more preferably 2000rpm to 4000rpm. If the spin coating speed is too low, the hole transport layer is too thick, and if the spin coating speed is too high, the hole transport layer is too thin, and the hole transport layer is too thin and too thick, both of which can cause imbalance between electrons and holes in the quantum dot device, and thus the performance of the device is poor.
The spin coating time may be 10s to 100s, and more preferably 30s to 60s. If the spin-coating time is too short, the hole transport layer contains a large amount of solvent and is not volatilized, the film forming effect of the electron transport layer is poor in the subsequent drying process, and if the spin-coating time is too long, the production efficiency is reduced.
The spin coating of the composite solution may be followed by a heat treatment. The temperature range of the heat treatment is 50 ℃ to 150 ℃, and more preferably 80 ℃ to 120 ℃. The heat treatment is to remove solvent molecules in the hole transport layer and to prevent residual solvent from affecting the film forming effect. If the temperature of the heat treatment is too low, the solvent molecules are difficult to completely remove, and if the temperature of the heat treatment is too high, the functional layer film structure of the photoelectric quantum dot device is easily damaged, and the photoelectric performance of the device is affected. In some embodiments of the present application, the time period for the heat treatment ranges from 10min to 60min. If the heat treatment time is too short, the solvent molecules are difficult to completely remove, and if the heat treatment time is too long, the functional layer film structure of the quantum dot device is easily damaged, and the photoelectric performance of the device is affected.
To better understand the present solution, a method for manufacturing a bottom-emitting QLED device is provided, which includes steps S110 to S310 or S120 to S320, and further includes a preprocessing step between step S110 and step S210 or between step S120 and step S220: and ultrasonically cleaning the anode substrate or the cathode substrate made of the transparent material in a cleaning reagent, and then drying, and specifically, ultrasonically cleaning in a detergent, deionized water, acetone, ethanol and/or deionized water, wherein the cleaning time is 2-30min each time.
For better understanding of the present solution, there is provided a method for manufacturing a top-emitting QLED device, comprising steps S110 to S310 or steps S120 to S320, and further comprising steps of depositing an anode or a cathode between steps S110 and S210 or between steps S120 and S220: depositing an anode material solution or a cathode material solution of a non-transparent material on the substrate to form an anode or a cathode, wherein the thickness is 5-300nm, preferably 50-150nm, and physical coating methods include, but are not limited to evaporation and sputtering.
In view of the fact that the QLED device may be additionally provided with a hole functional layer for improving the charge transport performance, the method for manufacturing the QLED device further includes the step of depositing at least one of the hole injection layer and the hole transport layer by a physical coating method. The hole injection layer and the hole transport layer are arranged according with the structural arrangement of the conventional QLED, and the deposition method of the hole injection layer or the hole transport layer is realized by a physical coating method, and the specific mode is not limited, and includes but not limited to a thermal evaporation coating method, an electron beam evaporation coating method, a magnetron sputtering method, a multi-arc ion coating method, a physical vapor deposition method, an atomic layer deposition method, a pulse laser deposition method and the like. Further, after the hole injection layer or the hole transport layer is deposited, heat treatment is performed respectively to remove the solvent in each layer, and for the hole injection layer, an oxide prepared from a metal precursor can be annealed and converted into a metal oxide by the heat treatment. The thickness of the hole transport layer is 5 to 100nm, and preferably, the thickness of the hole transport layer is 25 to 70nm. The thickness of the hole injection layer is 1 to 50nm, and preferably, the thickness of the hole injection layer is 5 to 20nm. The hole functional layer is too thin and too thick, which can cause the electron-hole imbalance inside the device, and further cause the performance of the device to be poor. The preparation method of the QLED comprises the steps of sequentially depositing a hole transport layer and a hole injection layer on a luminescent layer, and preparing an anode on the hole injection layer.
For a better understanding of the present solution, specific examples 1-5 are provided herein, as well as comparative example 1, wherein further details of the present solution are provided.
Example 1
An inverted QLED device with an antioxidant in an electron transport layer material comprises a substrate 110, a cathode 120, an electron transport layer 130, a light emitting layer 140, a hole transport layer 150, a hole injection layer 160 and an anode 170 which are arranged in a stacked mode, wherein the substrate 110 is made of a glass sheet, the cathode 120 is made of an ITO glass substrate, the electron transport layer 130 is made of MgZnO + BHA, the light emitting layer is made of CdSe/ZnS, the hole transport layer 150 is made of CBP, and the hole injection layer 160 is made of MoO 3 The anode 170 is made of Ag.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 15min each time, and drying at 100 ℃;
forming an electron transport layer with the thickness of 50nm on the processed ITO substrate by spin-coating an electron transport layer material solution in a glove box, wherein the electron transport layer material solution comprises MgZnO dispersed in ethanol, the doping proportion of Mg is 5%, the concentration of Mg is 20Mg/mL, and BHA with the mass fraction of 5% in terms of the mass of the MgZnO ethanol solution, and then annealing for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled sheet to form a luminescent layer with the thickness of 25nm, wherein the luminescent layer material solution comprises CdSe/ZnS core-shell structure quantum dots dispersed in n-octane and the concentration of the CdSe/ZnS core-shell structure quantum dots is 15mg/mL, and then annealing at 100 ℃ for 10min;
transferring the cooled substrate to an evaporator to evaporate a CBP material to form a hole transport layer with the thickness of 50 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 10 nm;
and transferring the treated substrate to an evaporator to evaporate an anode material to form an anode layer with the thickness of 100nm, wherein the anode material is Ag.
Example 2
An inverted QLED device with a light-emitting layer material containing an antioxidant comprises a substrate, a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, a hole injection layer and an anode which are arranged in a stacked mode, wherein the substrate is made of a glass sheet, the cathode is made of an ITO (indium tin oxide) glass substrate, the electron transport layer is made of MgZnO, the light-emitting layer is made of CdSe/ZnS + BHA, the hole transport layer is made of CBP (cubic boron nitride), and the hole injection layer is made of MoO (molybdenum oxide) 3 And the anode material is Ag. Wherein, in the luminescent layer, the mass fraction of BHA is 10 percent based on the total mass of the CdSe/ZnS core-shell structure quantum dots.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 15min each time, and drying at 100 ℃;
an electron transport layer material solution is coated on the processed ITO substrate in a glove box in a spinning mode to form an electron transport layer with the thickness of 50nm, the electron transport layer material solution comprises MgZnO dispersed in ethanol, the doping proportion of Mg is 5%, the concentration of Mg is 20Mg/mL, and then annealing is carried out for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled sheet to form a luminescent layer with the thickness of 25nm, wherein the luminescent layer material solution comprises CdSe/ZnS core-shell structure quantum dots dispersed in n-octane, the concentration of the CdSe/ZnS core-shell structure quantum dots is 15mg/mL, BHA with the mass fraction of 10% is calculated by the total mass of the CdSe/ZnS core-shell structure quantum dots dispersed in n-octane, and then annealing, wherein the annealing temperature is 100 ℃ and the annealing time is 10min;
transferring the cooled substrate to an evaporator to evaporate a CBP material to form a hole transport layer with the thickness of 50 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 10 nm;
and transferring the treated substrate to an evaporator to evaporate an anode material to form an anode layer with the thickness of 100nm, wherein the anode material is Ag.
Example 3
An inverted QLED device with an antioxidant in both an electron transport layer material and a light emitting layer material comprises a substrate, a cathode, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer and an anode which are arranged in a stacked mode, wherein the substrate is made of glass sheets, the cathode is made of an ITO glass substrate, the electron transport layer material is MgZnO + BHA, the light emitting layer material is CdSe/ZnS + BHA, the hole transport layer material is CBP, and the hole injection layer material is MoO 3 And the anode material is Ag. Wherein in the luminescent layer, the mass fraction of BHA is 10% based on the total mass of the CdSe/ZnS core-shell structure quantum dots.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 15min each time, and drying at 100 ℃;
forming an electron transport layer with the thickness of 50nm on the processed ITO substrate by spin-coating an electron transport layer material solution in a glove box, wherein the electron transport layer material solution comprises MgZnO dispersed in ethanol, the doping proportion of Mg is 5%, the concentration of Mg is 20Mg/mL, and BHA with the mass fraction of 5% in terms of the mass of the MgZnO ethanol solution, and then annealing for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled sheet to form a luminescent layer with the thickness of 25nm, wherein the luminescent layer material solution comprises CdSe/ZnS core-shell structure quantum dots dispersed in n-octane, the concentration of the CdSe/ZnS core-shell structure quantum dots is 15mg/mL, BHA with the mass fraction of 10% is calculated by the total mass of the CdSe/ZnS core-shell structure quantum dots dispersed in n-octane, and then annealing, wherein the annealing temperature is 100 ℃ and the annealing time is 10min;
transferring the cooled substrate to an evaporation machine for evaporating a CBP material to form a hole transport layer with the thickness of 50 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 10 nm;
and transferring the treated substrate to an evaporator to evaporate an anode material to form an anode layer with the thickness of 100nm, wherein the anode material is Ag.
Example 4
An inverted QLED device with a luminescent layer material containing an antioxidant comprises a substrate, a cathode, an electron transport layer, a luminescent layer, a hole transport layer, a hole injection layer and an anode which are arranged in a stacked mode, wherein the substrate is made of a glass sheet, the cathode is made of an ITO glass substrate, the electron transport layer is made of MgZnO, the luminescent layer is made of CdSe + PG, the hole transport layer is made of CBP, and the hole injection layer is made of MoO 3 And the anode material is Ag. Wherein, in the luminescent layer, based on the total mass of the CdSe quantum dots,the mass fraction of PG was 35%.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 15min each time, and drying at 100 ℃;
an electron transport layer material solution is coated on the processed ITO substrate in a glove box in a spinning mode to form an electron transport layer with the thickness of 85nm, the electron transport layer material solution comprises MgZnO dispersed in methanol, the doping proportion of Mg is 5%, the concentration of Mg is 45Mg/mL, and then annealing is carried out for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled wafer to form a luminescent layer with the thickness of 45nm, wherein the luminescent layer material solution comprises CdSe quantum dots dispersed in n-pentane and the concentration of the CdSe quantum dots is 35mg/mL, PG with the mass fraction of 35% is calculated by the total mass of the CdSe quantum dots dispersed in the n-pentane, and then annealing, wherein the annealing temperature is 100 ℃, and the annealing time is 20min;
transferring the cooled substrate to an evaporator to evaporate a CBP material to form a hole transport layer with the thickness of 60 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 20 nm;
and transferring the treated substrate to an evaporator to evaporate an anode material to form an anode layer with the thickness of 80nm, wherein the anode material is Ag.
Example 5
An inverted QLED device with an antioxidant in both an electron transport layer material and a light emitting layer material comprises a substrate, a cathode, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer and an anode which are arranged in a stacked mode, wherein the substrate is made of glass sheets, the cathode is made of an ITO glass substrate, the electron transport layer is made of MgZnO + BHT, the light emitting layer is made of CdSe + Irganox1010, the hole transport layer is made of CBP, and the hole injection layer is made of MoO 3 And the anode material is Ag. Wherein, the total mass of the CdSe quantum dots is countedThe mass fraction of Irganox1010 was 40%.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 20min each time, and drying at 100 ℃;
forming an electron transport layer with the thickness of 20nm on the processed ITO substrate by spin-coating an electron transport layer material solution in a glove box, wherein the electron transport layer material solution comprises MgZnO dispersed in propanol, the doping proportion of Mg is 5%, the concentration of Mg is 15Mg/mL, and BHT with the mass fraction of 25% by mass of the MgZnO ethanol solution, and then annealing for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled wafer to form a luminescent layer with the thickness of 30nm, wherein the luminescent layer material solution comprises CdSe quantum dots dispersed in n-octane, the concentration of the CdSe quantum dots is 30mg/mL, and Irganox1010 with the mass fraction of 40% based on the total mass of the CdSe quantum dots dispersed in n-octane, and then annealing, wherein the annealing temperature is 100 ℃ and the annealing time is 10min;
transferring the cooled substrate to an evaporator to evaporate a CBP material to form a hole transport layer with the thickness of 70 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 30 nm;
and transferring the treated substrate into an evaporation machine to evaporate an anode material to form an anode layer with the thickness of 100nm, wherein the anode material is Ag.
Comparative example 1
An inverted QLED device without an antioxidant in a preparation material comprises a substrate, a cathode, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer and an anode which are arranged in a stacked mode, wherein the substrate is made of a glass sheet, the cathode is made of an ITO glass substrate, the electron transport layer is made of MgZnO, the light emitting layer is made of CdSe/ZnS, the hole transport layer is made of CBP, and the hole injection layer is made of MoO 3 Anode materialIs Ag.
Correspondingly, the embodiment also provides a preparation method of the inverted QLED device, which includes:
providing a luminescent layer and an electron transport layer material solution;
sequentially placing the glass substrate with the ITO in a detergent, deionized water, acetone, ethanol and deionized water, performing ultrasonic treatment for 15min each time, and drying at 100 ℃;
an electron transport layer material solution is coated in a glove box in a spinning mode on the processed ITO substrate to form an electron transport layer with the thickness of 50nm, the electron transport layer material solution comprises MgZnO dispersed in ethanol, the doping proportion of Mg is 5%, the concentration of Mg is 20Mg/mL, and then annealing is carried out for 10min at the temperature of 100 ℃ in the glove box;
spin-coating a luminescent layer material solution on the cooled wafer to form a luminescent layer with the thickness of 25nm, wherein the luminescent layer material solution comprises CdSe/ZnS core-shell structure quantum dots dispersed in n-octane and the concentration of the CdSe/ZnS core-shell structure quantum dots is 15mg/mL, and then annealing, wherein the annealing temperature is 100 ℃ and the annealing time is 10min;
transferring the cooled substrate to an evaporator to evaporate a CBP material to form a hole transport layer with the thickness of 50 nm;
evaporating MoO on the treated substrate 3 Forming a hole injection layer with the thickness of 10 nm;
and transferring the treated substrate into an evaporation machine to evaporate an anode material to form an anode layer with the thickness of 100nm, wherein the anode material is Ag.
Experimental example 1: maximum current efficiency of the QLED devices of the different examples and comparative examples, current efficiency being the ratio of the amount of actually deposited or dissolved substance on the electrode during electrolysis to the amount of precipitation or dissolution calculated theoretically.
TABLE 1 different QLED device efficiencies
| Example 1 | Example 2 | Example 3 | Comparative example 1 | |
| CE max (Cd/A) | 17.4 | 18.5 | 22.7 | 15.2 |
As can be seen from the above results, for examples 1, 2,3 and comparative example 1, the CEs of experimental examples 1, 2,3 max The value of (Cd/A) is obviously higher than that of comparative example 1, especially example 3, and CE is obtained after the electron transport layer material and the luminescent layer material are simultaneously added with antioxidant max The value of (Cd/A) is higher than that of the antioxidant added to the material of the electron transport layer or the material of the light-emitting layer.
Experimental example 2: the life of different QLED devices is expressed by T95 life at 1000nit, wherein T95 represents the time for the manual maximum brightness to decay to 95%, and the T95 life at 1000nit is the time for the QLED devices to decay to 95%, namely about 950 nit.
TABLE 2 different QLED device lifetimes
| Example 1 | Example 2 | Example 3 | Comparative example 1 | |
| T95@1000nit(h) | 1329 | 1851 | 2825 | 856 |
From the above results, it can be seen that, for example 1, example 2, example 3 and comparative example 1, the values of the experimental examples 1, 2 and 3, which are each substantially higher than that of the comparative example 1, especially for example 3, after the antioxidant is added to the electron transport layer material and the light emitting layer material at the same time, the values of the t95@1000nit (h) are higher than those of the antioxidant added to the electron transport layer material or the light emitting layer material alone.
In summary, the antioxidant is added to the material of at least one of the electron transport layer and the quantum dot light emitting layer, so that the quantum dot quantum efficiency can be effectively prevented from being reduced, oxygen radicals can be prevented from being adsorbed on the surface of the material to influence the efficiency of the device, and the performance and the service life of the device can be effectively improved. In the preparation method, on the basis of the existing preparation method of the QLED device, the antioxidant is added into the material solution of the electron transmission layer or the quantum dot light-emitting layer, and the corresponding lamination can be obtained through deposition in various ways. The preparation process is simple and controllable, and is favorable for large-scale production and application.
The QLED device and the method for manufacturing the same provided by the present invention are described in detail above, and the principle and the embodiment of the present invention are illustrated herein by using specific examples, and the above description of the examples is only used to help understanding the method of the present invention and the core idea thereof, and it should be noted that, for those skilled in the art, many modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention, and in summary, the content of the present description should not be understood as a limitation to the present invention.
Claims (11)
1. A QLED device is characterized by comprising an anode, a light-emitting layer, an electron transport layer and a cathode which are arranged in a laminated manner, wherein at least one of the materials of the light-emitting layer and the electron transport layer comprises an antioxidant.
2. A QLED device according to claim 1, wherein the antioxidant is selected from one or more of dibutylhydroxytoluene, antioxidant 1010, antioxidant 1076, antioxidant 168, vitamin C, vitamin a, vitamin E, tea polyphenols, ethoxyquinoline, ethoxyquin, butylhydroxyanisole, tert-butylhydroquinone, propyl gallate.
3. A QLED device according to claim 1, wherein the molar fraction of the antioxidant in the light emitting layer and/or the electron transporting layer is in the range of 0.1% to 20%.
4. A QLED device according to claim 1 wherein the material of the light emitting layer further comprises quantum dots selected from one or more of quantum dots of a group II-VI compound semiconductor, group III-V compound semiconductor, group I-III-VI compound semiconductor, perovskite quantum dots.
5. The QLED device of claim 4, wherein the quantum dots are core-shell structured quantum dots.
6. A QLED device according to claim 1, wherein the material of the electron transport layer further comprises an inorganic oxide semiconductor, the inorganic oxide semiconductorThe oxide semiconductor is selected from ZnO and SnO 2 、TiO 2 And one or more of Mg or Al doped ZnO.
7. A QLED device according to claims 1 to 6, wherein the material of the light emitting layer consists of antioxidants and quantum dots; or alternatively
The material of the electron transport layer is composed of an antioxidant and an inorganic oxide semiconductor.
8. A preparation method of a QLED device is characterized by comprising the following steps:
respectively providing a luminescent layer material solution and an electron transport layer material solution;
depositing the luminescent layer material solution on an anode substrate to form the luminescent layer;
depositing the electron transport layer material solution on the light emitting layer to form the electron transport layer;
or depositing the electron transport layer material solution on a cathode substrate to form the electron transport layer;
depositing the luminescent layer material solution on the electron transport layer to form the luminescent layer;
wherein at least one of the luminescent layer material solution and the electron transport layer material solution includes an antioxidant.
9. The method of making a QLED device of claim 8, wherein the solution of light emitting layer material further comprises quantum dots dispersed in an alkane organic reagent; the solution of the electron transport layer material further comprises an inorganic oxide semiconductor dispersed in an alcohol organic reagent.
10. The method of claim 9, wherein the antioxidant is present in an amount of 1 to 50% by mass based on the total mass of the quantum dots dispersed in the alkane organic reagent or the inorganic oxide semiconductor dispersed in the alcohol organic reagent.
11. The method of claim 9, wherein the quantum dot concentration is 10-40 mg/mL.
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