Patent Application
20240284694
This disclosure claims priority of the Chinese patent disclosure with the Chinese Patent Disclosure No. 202111222067.6, filed in the China National Intellectual Property Administration on Oct. 20, 2021, and entitled “PREPARATION METHOD FOR QLED DEVICE, DISPLAY SUBSTRATE, AND DISPLAY APPARATUS”, which is incorporated herein by reference in its entirety.
The present disclosure relates to the field of display technologies, and more particularly, to a preparation method for QLED device, a display substrate, and a display apparatus.
QLED device is a multi-functional layer composite structure composed of an anode, a quantum dot light-emitting layer, an electron transport layer, and a cathode, when stimulated by electricity or light, electrons and holes are injected from their respective electrodes respectively, and combined to emit light on the quantum dot light-emitting layer. The quantum dot light emitting diode (Quantum Dot Light Emitting Diode, QLED) has advantages such as adjustable emission wavelength, narrow emission bandwidth, high light-emitting efficiency, and low cost, and so on, it has attracted more and more attention.
However, under the irradiation of blue light (450 nm), an interface reaction will occur between O2 and the quantum dot light-emitting layer to form sulfate, hydroxide, and oxide, thereby reducing the light-emitting efficiency or service life of the device.
Therefore, there is a need of providing a QLED device that may reduce the adverse effects of oxygen on the quantum dot light-emitting layer effectively, and improve the light-emitting efficiency and the service life of the QLED device.
Therefore, the present disclosure provides a preparation method for QLED device, a display substrate, and a display apparatus.
Embodiments of the present disclosure provide a preparation method for QLED device, including the steps: providing a substrate; forming a first electrode layer on the substrate; forming a quantum dot light-emitting layer on the first electrode layer in a reducing gas atmosphere; forming an electronic functional layer on the quantum dot light-emitting layer; and forming a second electrode layer on the electronic functional layer.
Alternatively, in some embodiments of the present disclosure, the reductive gas is selected from one or more of CO, NO, H2, H2S, ethylene, and acetylene.
Alternatively, in some embodiments of the present disclosure, in the step of forming the quantum dot light-emitting layer, a reductive gas catalyst is used to accelerate the step, the reductive gas catalyst is selected from one or more of Cu, Pt, and Au.
Alternatively, in some embodiments of the present disclosure, forming an electronic functional layer on a quantum dot light-emitting layer includes: forming an electronic functional layer on the quantum dot light-emitting layer under ultraviolet light irradiation.
Alternatively, in some embodiments of the present disclosure, before the step of forming a quantum dot light-emitting layer on the first electrode layer in an reducing gas atmosphere, the method further includes: forming a hole functional layer on the first electrode layer, and the hole functional layer is disposed between the first electrode layer and the quantum dot light-emitting layer. Alternatively, in some embodiments of the present disclosure, the step of forming a hole functional layer on the first electrode layer includes: forming a hole injection layer or a hole transport layer on the first electrode layer.
Alternatively, in some embodiments of the present disclosure, the step of forming a hole functional layer on the first electrode layer includes: forming a hole injection layer and a hole transport layer on the first electrode layer sequentially.
Alternatively, in some embodiments of the present disclosure, a material of the hole injection layer includes one or more of PEDOT:PSS (Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), MCC, CuPc (Copper phthalocyanin), F4-TCNQ (Tetracyanoquinodimethane-1,3-dimethylisoindolinone), HATCN (Hexacyanobenzenehexaazatriphenylene), a transition metal oxide, and a transition metal chalcogenide.
Alternatively, in some embodiments of the present disclosure, a material of the hole transport layer includes one or more of PVK (Polyvinylcarbazole), Poly-TPD (Poly(9,9-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,3,4-oxadiaz ole)), CBP (4,4′-Bis(carbazol-9-yl)biphenyl), TCTA(4,4′,4″-Tris(carbazol-9-yl)triphenylamine), and TFB (2,2′,7,7′-Tetrakis(N,N-di-pmethoxyphenylamine)-9,9′-spirobifluorene).
Alternatively, in some embodiments of the present disclosure, a material of the first electrode layer is selected from one or more of indium tin oxide, fluorine doped tin oxide, indium zinc oxide, graphene, and carbon nanotubes.
Alternatively, in some embodiments of the present disclosure, a material of the second electrode layer is selected from one or more of Al and Ag.
Alternatively, in some embodiments of the present disclosure, the first electrode layer is an anode layer, and the second electrode layer is a cathode layer.
Alternatively, in some embodiments of the present disclosure, the electronic functional layer includes an electron transport layer, and a material of the electron transport layer includes a metal oxide.
Alternatively, in some embodiments of the present disclosure, the metal oxide is selected from one or more of ZnO, SnO2, ITO, Fe2O3, CrO3, TiO2, WO3, CdO, CuO, and MoO2.
Alternatively, in some embodiments of the present disclosure, a material of the quantum dot light-emitting layer is selected from one or more of CdS, CdSe, CdTe, CdZnS, CdZnSe, CdSeS, ZnO, ZnS, ZnSe, ZnTe, ZnCdSe, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, CuInS, and CuInSe.
Alternatively, in some embodiments of the present disclosure, from the step of forming the quantum dot light-emitting layer to the step of forming the second electrode layer, the whole processes are in a reducing gas atmosphere.
Alternatively, in some embodiments of the present disclosure, after forming a second electrode layer on the electronic functional layer, the method further includes: encapsulating.
Alternatively, in some embodiments of the present disclosure, from the step of forming the quantum dot light-emitting layer to the step of encapsulating, the whole processes are in a reducing gas atmosphere.
Correspondingly, the embodiments of the present disclosure further provide a display substrate including a QLED device manufactured by the preparation method for the QLED device above.
Correspondingly, embodiments of the present disclosure further provide a display apparatus including the display substrate above.
According to the QLED device of the present disclosure, the reductive gas is continuously introduced during the forming of the quantum dot light-emitting layer to react with oxygen in the environment, thereby avoiding an interface reaction between the quantum dot light-emitting layer and the oxygen in the environment during the forming process of the quantum dot light-emitting layer, and further improving light-emitting efficiency or service life of the device. According to the QLED device prepared by the present disclosure, the device performance of the QLED device meet the commercial disclosure standard, thus advancing the goal of applying quantum dot electroluminescent technology to the display industry.
In order to more clearly explain the technical solutions in the embodiments of the present disclosure, the figures to be used in the description of the embodiments are briefly described below. It is apparent that the figures in the following description are merely some embodiments of the present disclosure. For those skilled in the art, without involving any creative effort, other figures may be obtained based on these figures.
Technical solutions in embodiments of the present disclosure will be clearly and completely described below with reference to the figures in the embodiments of the present disclosure. It is apparent that, the described embodiments are only a part of embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative effort fall within the protection scope of the present disclosure.
The embodiments of the present disclosure provide a preparation method for QLED device and a QLED device therefrom. Detailed description is given below. It should be noted that the order in which the following embodiments are described is not intended to limit the preferred order of the embodiments. Additionally, in the description of the present disclosure, the term “comprising/including” means “comprising/including but not limited to.” Various embodiments of the present disclosure may be presented in a form of range. It should be understood that the description in the form of range is merely for convenience and brevity, and should not be construed as a hard limitation on the scope of the disclosure. Therefore, it should be considered that the recited range description has specifically disclosed all possible subranges, as well as a single numerical value within that range. For Embodiment, it should be considered that a description of a range from 1 to 6 has specifically disclosed su-branges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and a single number within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Whenever a range of values is indicated herein, it is meant to include any recited number (fraction or integer) within the indicated range.
In the present disclosure, the term “and/or” is used to describe the association relationship of associated objects, and means that there may be three relationships, for example, “A and/or B” may refer to three relationships: for example, A exists alone, A and B exist at the same time, and B exists alone, where A and B may be singular or plural.
In the present disclosure, the terms “at least one” or “one or more” refer to one or more, and “a plurality of/multiple” refers to two or more. The terms “at least one”, “at least one of the followings”, or the like, refer to any combination of the items listed, including any combination of a single item or a plurality of items. For example, “at least one of a, b, or c” or “at least one of a, b, and c” may refer to: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, and c may be single or plural (multiple).
The inventor found in the experiment that: with the increase of the oxygen content in the environment, a light-emitting efficiency and a service life of the device will decrease gradually, thereby leads to the decrease of the light-emitting efficiency and the service life of the device.
In the step of research and practice of the prior art, the inventor of the present disclosure further found that, during the manufacturing process of the top emitting device, a reductive gas catalyst is introduced into the quantum dot light-emitting layer (QD layer), so that the problems of low light-emitting efficiency and poor service life caused by the interface reaction between the quantum dot light-emitting layer and O2. An embodiment of the present disclosure provides a preparation method for QLED device, referring to
In one embodiment, the reductive gas is selected from one or more of CO, NO, H2, H2S, ethylene, and acetylene. In an embodiment, in the step of forming a quantum dot light-emitting layer, the process is accelerated by using a reductive gas catalyst, the reductive gas catalyst is selected from one or more of Cu, Pt, and Au.
In an experiment, the inventor further found that: the higher resistance of the electronic functional layer (ETL layer) is not conducive to electron transport, which leads to the balance of hole-electron injection, and eventually leads to the decrease of the light-emitting efficiency and the service life of the device.
In the process of research and practice of the prior art, the inventor of the present disclosure further found that, during the manufacturing process of a top emitting device, the ultraviolet (UV) light is used to irradiate a metal oxide layer can improve a weak electron transport performance of the electron transport layer (ETL layer) due to the high resistance.
In one embodiment, the step of forming an electronic functional layer on a quantum dot light-emitting layer includes: forming an electronic functional layer on a quantum dot light-emitting layer under a ultraviolet irradiation.
In one embodiment, before the step of forming a quantum dot light-emitting layer on the first electrode layer in a reducing gas atmosphere, the method further includes: forming a hole functional layer on the first electrode layer, and the hole functional layer is disposed between the first electrode layer and the quantum dot light-emitting layer.
In one embodiment, the step of forming a hole functional layer on the first electrode layer includes:
forming a hole injection layer on the first electrode layer; or forming a hole transport layer on the first electrode layer; or forming a hole injection layer and a hole transport layer on the first electrode layer sequentially.
In one embodiment, a material of the hole injection layer includes one or more of PEDOT:PSS(Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), MCC, CuPc (Copper phthalocyanin), F4-TCNQ (Tetracyano-quinodimethane-1,3-dimethylisoindolinone), HATCN (Hexacyanobenzenehexaazatriphenylene), a transition metal oxide, and a transition metal chalcogenide; and/or a material of the hole transport layer includes one or more of PVK (Polyvinylcarbazole), Poly-TPD (Poly(9,9-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,3,4-oxadiaz ole)), CBP (4,4′-Bis(carbazol-9-yl)biphenyl), TCTA(4,4′,4″-Tris(carbazol-9-yl)triphenylamine), and TFB (2,2′,7,7′-Tetrakis(N,N-di-pmethoxyphenylamine)-9,9′-spirobifluorene).
A material of the first electrode layer includes one or more of indium tin oxide, fluorine doped tin oxide, indium zinc oxide, graphene, and carbon nanotubes; and/or a material of the second electrode layer includes one or more of Al and Ag. A material of the electronic functional layer includes metal oxide. Furthermore, the metal oxide is selected from but not limited to one or more of ZnO, SnO2, ITO, Fe2O3, CrO3, TiO2, WO3, CdO, CuO, and MoO2. For example, in one embodiment, the material of the electron transport layer includes metal oxide, and the material of the electron transport layer is selected from, but not limited to, one or more of ZnO, SnO2, ITO, Fe2O3, CrO3, TiO2, WO3, CdO, CuO, and MoO2.
In the present disclosure, the reductive gas catalyst is continuously introduced when the quantum dot light-emitting layer is formed, so as to remove oxygen in the environment, to reduce or even cut off the negative influence of the oxygen on the quantum dot light-emitting layer, thus to increase the light-emitting efficiency and the service life of the device. Introducing Ultraviolet (UV) light for irradiation when forming the electronic functional layer can reduce the resistance of the metal oxide, so as to increase the electron transmitting efficiency, to ensure the balance of the hole-electron injection, and finally to increase the light-emitting efficiency and the service life of the device.
In the embodiments of the present disclosure, a quantum dot for the quantum dot light-emitting layer can be an alloy quantum dot or a core-shell quantum dot. Furthermore, a material of the quantum dot light-emitting layer is selected from one or more of CdS, CdSe, CdTe, CdZnS, CdZnSe, CdSeS, ZnO, ZnS, ZnSe, ZnTe, ZnCdSe, GaAs, GaP, GaSb. HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, CuInS, and CuInSe. The core-shell quantum dot is selected from but not limited to group II-IV compounds (e.g. CdS, CdSe) and group III-V compounds (e.g. InP, InAs).
In the embodiments of the present disclosure, the first electrode layer can be an anode layer, for Embodiment, the material of the first electrode layer is selected from one or more of indium tin oxide (e.g. ITO), fluorine doped tin oxide, indium zinc oxide, graphene, and carbon nanotubes. The second electrode layer is a cathode layer, for Embodiment, the material of the second electrode layer is selected from one or more of Al and Ag.
In one embodiment, referring to
In another embodiment, referring to
It can be seen that, from the step of forming the quantum dot light-emitting layer to the step of forming the second electrode layer, the whole process is performed in a reducing gas atmosphere.
In a preferred embodiment, the preparation method for QLED device includes the following steps:
Firstly, forming an anode layer, a hole injection layer (HIL), and a hole transport layer (HTL) on a substrate sequentially. A material of the anode layer may be conventional in the art, a material of the hole injection layer (HIL) may be conventional in the art, and a material of the hole transport layer (HTL) may be conventional in the art.
Then, forming a quantum dot light-emitting layer on the hole transport layer. When forming the quantum dot light-emitting layer, the reductive gas catalyst is continuously introduced for oxygen removal treatment. Because under the irradiation of blue light (450 nm), when the QD layer is spin-coated, the QD layer will react with the oxygen in the environment at the interface, to generate sulfate, hydroxide, and oxide, thereby destroying the original structure of the QD layer, and finally decreasing the light-emitting efficiency and the service life of the device. Therefore, in the present disclosure, the reductive gas is continuously introduced during the process of forming the quantum dot light-emitting layer, so that, the oxygen in the environment can be effectively reacted and consumed. It should be noted that, in an actual preparation process, because the volume of the glove box is too large, and a surface dust layer accumulates with the using time. If the reductive gas is introduced into the whole glove box, a large number amount of gas source will be needed and the surface dust layer will be further accumulated on a surface of the quantum dot. Therefore, there will be a lot of dirt on the surface of the quantum dot, the quantum dot will eventually not be lighted up, and the light-emitting efficiency may be 0. As is shown in
Then, forming an electron transport layer (ETL) is prepared on the quantum dot light-emitting layer continuously. In the step of forming the electron transport layer, ultraviolet (UV) light irradiation is continuously used throughout the whole process, because the material of the ETL is generally a metal oxide semiconductor material, has an extremely strong absorption rate for ultraviolet light, and can change after absorbing the ultraviolet light. The UV irradiation can also promote bound electrons in the valence band to be excited by light energy to jump to the conduction band, forming free moving electrons, that is, the number of carriers in the conduction band increases, the conductivity of the material increases, the resistivity of the material decreases, and the resistance value does not increase again with the disappearance of the light irradiation. Most of the increase, if any, is caused due to the oxygen being absorbed again, so it is necessary to disconnect the light irradiation after the device is encapsulated, as shown in
Finally, forming the cathode layer on the electron transport layer, and then encapsulating.
In the preparation method for QLED device above, the reductive gas is closed after the encapsulating is finished. The reductive gas can be CO, NO, H2, H2S, ethylene, acetylene, and mixed gas thereof. The material of the electron transport layer (ETL) may be ZnO, SnO2, ITO (Indium tin oxide), Fe2O3, CrO3, TiO2, WO3, CdO, CuO, MoO2 and other semiconductor materials.
An embodiment of the present disclosure further provides a QLED device, which is manufactured by the above preparation method for QLED device.
In an embodiment, referring to
The present disclosure further provides a display substrate including the QLED device manufactured above.
The present disclosure further provides a display apparatus including the display substrate described above.
The present disclosure has been subjected to a plurality of experiments successively, now a part of the experimental results is taken as a reference for further detailed description of the invention, and the present disclosure will be described in detail below with reference to specific embodiments.
The following embodiments are carried out with top-emitting quantum dot devices as experimental subjects.
This example provides a preparation method for QLED device, including following steps:
This example provides a QLED device manufactured by the preparation method for QLED device of Example 1, except for, using reductive gas CO for the deoxidization treatment. Referring to
This example provides a QLED device manufactured by the preparation method for QLED device of Example 1, except for, using reductive gas H2 for the deoxidization treatment. Referring to
This example provides a QLED device manufactured by the preparation method for QLED device of Example 1, except for, using ethylene as the reductive gas for the deoxidization treatment. Referring to
The Comparative Example 1 provides a QLED device that has neither reductive gas catalyst nor ultraviolet irradiation treatment. The QLED device includes an anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode layer sequentially stacked on a substrate. Specifically, a structure of the QLED device is: ITO/MCC/TFB/QDs/ZnO/Ag, wherein, electrode is prepared by an evaporation method, and MCC, TFB, QDs, and ZnO are prepared by coating.
The Comparative Example 2 provides a QLED device, compared with Example 1, a method for manufacturing the QLED device of Comparative Example 2 has no reductive gas but has ultraviolet irradiation treatment. The QLED device includes an anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode layer sequentially stacked on a substrate. Specifically, a structure of the QLED device is: ITO/MCC/TFB/QDs/ZnO (UV)/Ag, wherein, electrode is prepared by an evaporation method, and MCC, TFB, QDs, and ZnO are prepared by coating.
The Comparative Example 3 provides a QLED device which is prepared by a preparation method for the QLED device according to Example 1, in which an reductive gas catalyst is used but there is no ultraviolet irradiation treatment. The QLED device includes an anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode layer sequentially stacked on a substrate. Specifically, a structure of the QLED device is: ITO/MCC/TFB/QDs (using CO as the reductive gas)/ZnO/Ag, in which the electrode is prepared by an evaporation method, and MCC, TFB, QDs, and ZnO are prepared by coating.
CE@max, CE@1 knit, and T95@1 knit of QLED devices prepared in Example 2, Example 3, Example 4, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were investigated at a current of 2 mA, respectively, and results are shown in Table 1, respectively.
It can be seen from Table 1 that the service life T95 @ 1 Knit of the device and the luminous efficiency Ce @ 1 Knit under low brightness can be increased by introducing the reducing gas catalyst and the ultraviolet irradiation treatment respectively, and when the reductive gas catalyst and the ultraviolet irradiation treatment are introduced at the same time, the luminous efficiency under the service life and low brightness of the device is further increased, and the effect of the H2 reductive gas catalyst in different types of gases is optimal; it is indicated that the reductive gas catalyst and the ultraviolet irradiation process can weaken or even isolate the interface reaction between O2 and the QD layer in the spin-coating environment and reduce the resistance of the ETL layer, thereby achieving the purpose of increasing the luminous efficiency and service life of the device.
The present application provides a method for optimizing a QLED device, in which mainly for the QD layer and the TEL layer, a reductive gas is used to conduct deoxidation treatment under the presence of a catalyst in a QD layer spin coating stage; and ultraviolet (UV) irradiation is continuously performed in the ETL layer spin coating stage. The QLED device obtained in the present application can reduce the adverse effect of oxygen on the QD layer and the disadvantage of high resistance and low electron transport efficiency of the ETL layer.
In the above-mentioned embodiments, the description of each embodiment has its own emphasis, and some of the embodiments that are not described in detail in certain embodiments may refer to the related description of other embodiments.
The preparation method for QLED device, the display substrate, and the display apparatus according to embodiments of the present disclosure are described in detail above. The principles and embodiments of the present disclosure have been described with reference to specific embodiments, and the description of the above embodiments is merely intended to aid in the understanding of the method of the present disclosure and its core idea. At the same time, changes may be made by those skilled in the art to both the specific implementations and the scope of disclosure in accordance with the teachings of the present disclosure. In view of the foregoing, the content of the present specification should not be construed as limiting the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111222067.6 | Oct 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/117331 | 9/6/2022 | WO |
