CN113130832A - Quantum dot film and preparation method thereof, quantum dot light-emitting diode and preparation method thereof - Google Patents
Quantum dot film and preparation method thereof, quantum dot light-emitting diode and preparation method thereof Download PDFInfo
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Abstract
The invention provides a preparation method of a quantum dot film, which comprises the following steps: providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film; and adding a target ligand into the first quantum dot film, and annealing to prepare the quantum dot film with the target ligand bonded on the surface. The preparation method of the quantum dot film provided by the invention can introduce the target ligand on the surface of the initial quantum dot on the premise of keeping the optical performance of the original quantum dot unaffected, and particularly can replace the ligand on the surface of the initial quantum dot to introduce the target ligand.
Description
Technical Field
The invention belongs to the technical field of quantum dots, and particularly relates to a quantum dot film and a preparation method thereof, and a quantum dot light-emitting diode and a preparation method thereof.
Background
The quantum dot is a nanocrystal with the size of 1 nm-100nm, has a remarkable quantum confinement effect in three-dimensional size, has unique optoelectronic properties such as adjustable wavelength along with size and components, narrow peak width, high luminous efficiency, stable optical performance and the like, and excellent solution processing characteristics, and is widely concerned by people in the fields of light emitting diodes, illumination, biological marking, lasers, solar cells and the like. In particular, the gradual increase in efficiency and lifetime of red, green and blue quantum dot light emitting diode (QLED) devices in recent years has marked the arrival of the era of wide application of quantum dot light emitting diodes as novel displays.
The quantum dot ligand plays an important role in the preparation process of the quantum dot, and is mainly embodied in the following aspects: firstly, the ligand can significantly influence the nucleation and growth process of the quantum dots; secondly, the ligand is used as a coordination solvent, so that the defect state indicated by the quantum dot can be effectively passivated, and the luminescence property is improved; thirdly, the ligand can enable the quantum dots to keep excellent dispersity in the solvent, and the excellent dispersity is the key for preparing the photoelectric device by forming the quantum dots into a film; fourthly, the ligand can reduce mutual agglomeration among the quantum dots and prevent the quantum dots from aggregating and precipitating; fifth, the ligands can typically significantly affect the bandgap of the quantum dots, thereby affecting the optoelectronic properties. In the quantum dot light-emitting diode, the surface ligand of the quantum dot has obvious influence on the photoelectric performance of the quantum dot, and the reasonable selection of the ligand has important significance for improving the photoelectric performance of the quantum dot light-emitting diode. In the existing ligand exchange technology, a ligand with strong coordination capacity is usually adopted to replace a ligand with weak coordination capacity, so as to obtain a quantum dot with the surface combined with the ligand with strong coordination capacity. Such as: the original long-chain ligands on the surfaces of the quantum dots are exchanged by adopting the short-chain ligands, so that the injection and transmission of carriers are improved, and the performance index of the device is obviously improved. This type of exchange is generally more complete due to the problem of strong and weak coordination. However, if ligand with weak coordination ability is adopted to exchange ligand with strong coordination ability, the ligand exchange rate in the process is usually low, and the residual ligand still has great influence on the application of quantum dots. Such as: when mercaptan is used as a sulfur source to prepare the quantum dots, the mercaptan serves as both the sulfur source and the surface ligand in the reaction. When ligand exchange is carried out on the quantum dots prepared by using mercaptan as a sulfur source, the ligand replacement of conventional ligands (such as carboxylic acid and amine) is difficult to carry out due to the strong coordination capacity of the mercaptan and the quantum dots. Therefore, it is important to find a rapid, effective, convenient and universal surface ligand replacement method.
Disclosure of Invention
The invention aims to provide a quantum dot film and a preparation method thereof, and aims to solve the problem that the ligand replacement on the surface of the existing quantum dot is limited by the coordination capacity of a ligand.
Another objective of the present invention is to provide a quantum dot light emitting diode and a method for manufacturing the same.
The technical scheme adopted by the invention is as follows:
the invention provides a preparation method of a quantum dot film, which comprises the following steps:
providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
and adding a target ligand into the first quantum dot film, and annealing to prepare the quantum dot film with the target ligand bonded on the surface.
The invention provides a quantum dot film, wherein the quantum dot is prepared by the preparation method of the quantum dot film.
The third aspect of the present invention provides a method for preparing a quantum dot light emitting diode, which at least comprises the following steps:
providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
and adding a target ligand into the first quantum dot film, and annealing to prepare the quantum dot film with the target ligand bonded on the surface.
The invention provides a quantum dot light-emitting diode in a fourth aspect, which comprises an anode and a cathode which are oppositely arranged, and a quantum dot light-emitting layer arranged between the anode and the cathode, wherein the quantum dot light-emitting layer is prepared by the preparation method of the quantum dot light-emitting film.
The preparation method of the quantum dot film provided by the invention comprises the steps of carrying out ultraviolet irradiation treatment on the initial quantum dot film to enable the initial ligand of the initial quantum dot in the initial quantum dot film to fall off, adding the target ligand into the obtained first quantum dot film, and finally preparing the quantum dot film with the target ligand bonded on the surface. Specifically, if the initial quantum dots in the initial quantum dot film contain the initial ligands, the ultraviolet light can open and cut covalent bonds in the initial ligands when ultraviolet irradiation treatment is carried out, and the purpose of removing the surface ligands of the initial quantum dots is achieved. And cleaning to obtain the first quantum dot film without the initial ligand. Further, a target ligand is added on the first quantum dot film, and the target ligand is combined on the surface of the first quantum dot in the first quantum dot film, so that the quantum dot film with the target ligand combined on the surface is finally obtained. The preparation method of the quantum dot film provided by the invention can introduce the target ligand on the surface of the initial quantum dot on the premise of keeping the optical performance of the original quantum dot unaffected, and particularly can replace the ligand on the surface of the initial quantum dot to introduce the target ligand. The method is simple to operate, mild in condition, high in efficiency, high in speed and universal, and is beneficial to large-scale application of the quantum dot film.
The quantum dot film provided by the invention is prepared by the method, so that the selection of the quantum dot surface ligand has higher flexibility.
The preparation method of the quantum dot light-emitting diode at least comprises the preparation method of the quantum dot film. Specifically, if the initial quantum dots in the initial quantum dot thin film contain the initial ligand, when ultraviolet irradiation treatment is carried out, the covalent bonds in the initial ligand can be opened and cut by ultraviolet light, and the purpose of removing the ligand on the surface of the initial quantum dots is achieved, so that the first quantum dot thin film containing no initial ligand is obtained. Further, a target ligand is added on the first quantum dot film, and the target ligand is combined on the surface of the first quantum dot in the first quantum dot film, so that the quantum dot film with the target ligand combined on the surface is finally obtained. Therefore, the preparation method of the quantum dot light-emitting diode provided by the invention can introduce the target ligand on the surface of the initial quantum dot on the premise of keeping the optical performance of the original quantum dot unaffected, and particularly can introduce the target ligand by replacing the ligand on the surface of the initial quantum dot. The method is simple to operate, mild in condition, high in efficiency, high in speed and universal, and is beneficial to large-scale application of the quantum dot film.
According to the quantum dot light-emitting diode provided by the invention, the quantum dot film is prepared by the method, so that the selection of the surface ligand of the quantum dot in the quantum dot film has higher flexibility.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a flow chart of a process for preparing a quantum dot thin film according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a quantum dot light emitting diode according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.
As shown in fig. 1, a first aspect of an embodiment of the present invention provides a method for preparing a quantum dot thin film, including the following steps:
s01, providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
s02, adding a target ligand into the first quantum dot film, annealing, and preparing the quantum dot film with the target ligand bonded on the surface.
According to the preparation method of the quantum dot film, provided by the embodiment of the invention, the initial quantum dot film is subjected to ultraviolet irradiation treatment in an oxygen-containing atmosphere, so that the initial ligand of the initial quantum dot in the initial quantum dot film falls off, the target ligand is added into the obtained first quantum dot film, and the quantum dot film with the target ligand bound on the surface is finally prepared. Specifically, if the initial quantum dots in the initial quantum dot film contain the initial ligands, the ultraviolet light can open and cut covalent bonds in the initial ligands when ultraviolet irradiation treatment is carried out, and the purpose of removing the surface ligands of the initial quantum dots is achieved. And cleaning to obtain the first quantum dot film without the initial ligand. Further, a target ligand is added on the first quantum dot film, and the target ligand is combined on the surface of the first quantum dot in the first quantum dot film, so that the quantum dot film with the target ligand combined on the surface is finally obtained. According to the preparation method of the quantum dot film provided by the embodiment of the invention, on the premise that the optical performance of the original quantum dot is not influenced, the target ligand can be introduced into the surface of the initial quantum dot, and particularly, the target ligand is introduced by replacing the ligand on the surface of the initial quantum dot. The method is simple to operate, mild in condition, high in efficiency, high in speed and universal, and is beneficial to large-scale application of the quantum dot film.
Specifically, in step S01, an initial quantum dot thin film to be processed is provided, and the initial quantum dot thin film at least contains initial quantum dots. The initial quantum dots can be quantum dots with initial ligands on the surface or quantum dots without surface ligands. However, in the embodiment of the present invention, when the surface of the initial quantum dot contains the initial ligand, it is more meaningful to perform the ultraviolet irradiation treatment in the oxygen-containing atmosphere.
In some embodiments, the quantum dot may be a quantum dot core having only a core structure, or may be a quantum dot having a core-shell structure. In some embodiments, the core of the quantum dot, the core of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each independently selected from at least one of a group II-VI semiconductor compound, a group III-V semiconductor compound, and a group IV-VI semiconductor compound. Wherein the group II-VI semiconductor compounds include, but are not limited to, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe; group II-V semiconductor compounds include, but are not limited to, GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaGaGaAs, GaSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InNP, InNAs, InNSb, InAlPAs, InAlPSb; group IV-VI semiconductor compounds include, but are not limited to, SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe.
In some embodiments, the initial quantum dots in the initial quantum dot thin film have thiol-based initial ligands. The initial ligand of mercaptan is difficult to displace from the surface of the quantum dot through conventional ligand displacement, but the initial ligand of mercaptan which is difficult to remove from the surface of the quantum dot can be removed by adopting ultraviolet irradiation treatment under oxygen-containing atmosphere provided by the embodiment of the invention, and the combination of other surface ligands, especially surface ligands with weak coordination capacity is realized, so that the exchange requirements of ligands with different coordination capacities are met. In some embodiments, the thiol-based primary ligand is selected from at least one of propanethiol, n-butanethiol, hexanethiol, n-octanethiol, isooctane thiol, dodecanethiol, tert-dodecanethiol, tetradecanethiol, hexadecanethiol, octadecanethiol, and the like, but is not limited thereto.
In the embodiment of the invention, the initial ligand on the surface of the initial quantum dot in the initial quantum dot film is removed by carrying out ultraviolet irradiation treatment on the initial quantum dot film.
In the embodiment of the present invention, the ultraviolet irradiation treatment includes an ultraviolet wavelength capable of opening and cutting a covalent bond in an organic ligand. In some embodiments, the initial quantum dot film is subjected to an ultraviolet irradiation treatment under ultraviolet light having wavelengths of 254nm and 185nm to irradiate the initial quantum dots. In some embodiments, the initial quantum dot film is subjected to an ultraviolet irradiation treatment under ultraviolet light having a wavelength of 185 nm. The covalent bonds in the organic ligands can be directly opened and cut through the action of ultraviolet light with the wavelengths of 254nm and 185nm or 185nm, so that the effect of removing weak ligands on the surface is achieved. In some embodiments, the step of subjecting the initial quantum dot thin film to ultraviolet irradiation treatment is performed under an oxygen-containing atmosphere. Namely: the ultraviolet irradiation treatment of the initial quantum dot film comprises the following specific steps: and carrying out ultraviolet irradiation treatment on the initial quantum dot film in an oxygen-containing atmosphere. On one hand, the ultraviolet light can open and cut off the covalent bond in the initial ligand, and the purpose of removing the initial quantum dot surface ligand is achieved; on the other hand, in an oxygen-containing atmosphere, the ultraviolet light beam decomposes oxygen molecules in the air to generate free oxygen, and ozone generated by combining the free oxygen and other oxygen molecules has extremely high oxidation effect on conventional organic ligands, particularly has extremely high oxidation effect on thiol initial ligands which have strong reducibility and are tightly combined with quantum dot ligands, and can quickly oxidize the strong coordination ligands, thereby playing a role in quickly removing surface strong ligands. Particularly, thiol initial ligands which are difficult to remove on the surface of the quantum dots can be removed.
Wherein, the oxygen-containing atmosphere refers to an atmosphere containing oxygen, including but not limited to an air atmosphere. Wherein, oxygen molecules in the oxygen-containing atmosphere are decomposed into free oxygen under ultraviolet irradiation treatment, and then combined with other oxygen molecules to generate ozone. Ozone has extremely strong oxidation effect on conventional organic ligands, particularly has extremely strong oxidation effect on initial thiol ligands which have strong reducibility and are tightly combined with quantum dot ligands, and can quickly oxidize the strong coordination ligands, so that the effect of quickly removing the strong ligands on the surfaces of the initial quantum dots is achieved, and the purpose of replacing the ligands with strong coordination capacity on the surfaces of the quantum dots with the ligands with weak coordination capacity is achieved.
In some embodiments, the initial quantum dot film is subjected to ultraviolet irradiation treatment under an oxygen-containing atmosphere and ultraviolet light with a wavelength of 185 nm. In this case, the ultraviolet light with a wavelength of 185nm can decompose oxygen into free oxygen, which then reacts with oxygen molecules to form ozone with a very strong oxidizing ability, thereby destroying the ligands with strong reducibility on the surface of the quantum dots.
According to the embodiment of the invention, the initial quantum dot film is subjected to ultraviolet irradiation treatment, particularly the initial quantum dot film is subjected to ultraviolet irradiation treatment in an oxygen-containing atmosphere, so that the problem that the quantum dot ligands cannot be completely exchanged depending on the strength of the ligand coordination capacity is solved, the flexibility and operability of ligand exchange with different strength of the ligand coordination capacity are obviously improved, and the requirement in the ligand exchange process is met.
In some embodiments, the initial quantum dot film is placed in an ultraviolet ozone cleaning machine for ultraviolet irradiation treatment. In some embodiments, the uv wavelength of the low pressure uv mercury lamp in the uv ozone cleaning machine is set to emit uv light containing at least 185 nm.
In some embodiments, the time for performing the ultraviolet irradiation treatment on the initial quantum dot thin film is 10min to 60 min. In this case, the initial ligands on the surface of the initial quantum dots can be effectively removed without affecting the performance of the initial quantum dots. If the ultraviolet irradiation treatment time is too short and is less than 10min, the initial ligand on the surface of the initial quantum dot may not be sufficiently removed; if the ultraviolet irradiation treatment time is too long and exceeds 60min, the quantum dots may be damaged, and particularly, in an oxygen-containing atmosphere, the irradiation treatment time is too long, the ozone content generated by ultraviolet oxidation of oxygen is too much, the quantum dots may be oxidized, the surface damage may be caused to the quantum dots, and the surface defects are introduced, so that the optical performance of the quantum dots is affected.
And after the initial quantum dot film is subjected to ultraviolet irradiation treatment, the initial ligand on the surface of the initial quantum dot falls off to form a first quantum dot. In addition, impurities may be introduced when the initial ligand is dropped during the ultraviolet irradiation treatment. If the dropped initial ligand and the impurities possibly introduced are not removed, the subsequent binding of the target ligand on the surface of the quantum dot is influenced. In particular, when the coordination ability of the initial ligand to the quantum dot is greater than that of the target ligand to the quantum dot, the binding of the target ligand to the surface of the quantum dot is seriously affected. And residual impurities can also remain in the film layer, which affects the luminescence property of the finally obtained quantum dot film. Therefore, in the embodiment of the present invention, after the step of performing the ultraviolet irradiation treatment on the initial quantum dot thin film, the obtained quantum dot thin film is subjected to a cleaning treatment to remove the initial ligand that falls off and other impurities that may be generated under the ultraviolet irradiation treatment.
In some embodiments, the method of the cleaning process is: and cleaning the initial quantum dot film subjected to ultraviolet irradiation treatment by using a polar solvent. The polar reagent can clean and remove initial ligands generated in the ultraviolet irradiation treatment process and impurities possibly introduced; but also can avoid dissolving away the quantum dot film. In some embodiments, the polar solvent is selected from organic alcohol solvents. In some embodiments, the organic alcohol reagent is selected from at least one of methanol, ethanol, isopropanol, but is not limited thereto, and is preferably ethanol, which is non-toxic and inexpensive.
In the step S02, the target ligand is added to the first quantum dot thin film, and the first ligand is bound to the surface of the first quantum dot not containing the initial ligand, thereby forming a quantum dot thin film having the target ligand bound to the surface. In the embodiment of the invention, the selection of the initial ligand is not strictly limited, and the initial ligand can be a ligand with weak coordination capacity or a ligand with strong coordination capacity, so that the bottleneck that the conventional ligand with strong coordination capacity replaces the ligand with weak coordination capacity can be broken through. In some embodiments, the target ligand is selected from the group consisting of carboxylic acid ligands, amine ligands, phosphine oxide ligands, and phosphine ligands having a carbon number of less than or equal to 30. Particularly, when the initial ligand of the initial quantum dot in the initial quantum dot film is a thiol initial ligand; the target ligand is selected from carboxylic acid ligands, amine ligands, phosphine oxide ligands and phosphine ligands with the carbon atom number less than or equal to 30, and the thiol initial ligand with strong coordination capacity on the surface of the quantum dot can be replaced by the target ligand with weak coordination capacity by the quantum dot replacement method.
In some embodiments, after the step of adding a target ligand to the first quantum dot, the method further comprises: and cleaning the obtained quantum dots combined with the target ligand by using a polar solvent to remove excessive target ligand, so as to avoid the influence of residual target ligand on the luminescence property of the quantum dot film due to the fact that the residual target ligand enters the quantum dot film.
According to the embodiment of the invention, the organic solvent in the quantum dot film is removed through annealing treatment, and the compactness of the film is improved. In some embodiments, the annealing treatment conditions are: annealing for 1-20 min at 50-80 deg.c. If the annealing temperature is too high or the annealing time is too long, the ligand bound on the surface of the quantum dot may be affected, and even the quantum dot in the quantum dot film may be affected.
In a second aspect, the embodiments of the present invention provide a quantum dot thin film, where the quantum dots are prepared by the above method for preparing a quantum dot thin film.
The quantum dot film provided by the embodiment of the invention is prepared by the method, so that the selection of the quantum dot surface ligand has higher flexibility.
The third aspect of the embodiments of the present invention provides a method for manufacturing a quantum dot light emitting diode, which at least includes the following steps:
s01, providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
s02, adding a target ligand into the first quantum dot film, annealing, and preparing the quantum dot film with the target ligand bonded on the surface.
The preparation method of the quantum dot light-emitting diode provided by the embodiment of the invention at least comprises the preparation method of the quantum dot film. Specifically, if the initial quantum dots in the initial quantum dot thin film contain the initial ligand, when ultraviolet irradiation treatment is carried out, the covalent bonds in the initial ligand can be opened and cut by ultraviolet light, and the purpose of removing the ligand on the surface of the initial quantum dots is achieved, so that the first quantum dot thin film containing no initial ligand is obtained. Further, a target ligand is added on the first quantum dot film, and the target ligand is combined on the surface of the first quantum dot in the first quantum dot film, so that the quantum dot film with the target ligand combined on the surface is finally obtained. Therefore, the preparation method of the quantum dot light-emitting diode provided by the embodiment of the invention can introduce the target ligand on the surface of the initial quantum dot on the premise of keeping the optical performance of the original quantum dot unaffected, and particularly can replace the ligand on the surface of the initial quantum dot to introduce the target ligand. The method is simple to operate, mild in condition, high in efficiency, high in speed and universal, and is beneficial to large-scale application of the quantum dot film.
In the embodiments of the present invention, the method for preparing the quantum dot thin film with the target ligand bound to the surface, the selection of the initial quantum dot and the surface ligand condition are all as described above.
Specifically, in step S01, an initial quantum dot thin film to be processed is provided, and the initial quantum dot thin film at least contains initial quantum dots. The initial quantum dots can be quantum dots with initial ligands on the surface or quantum dots without surface ligands. However, in the embodiment of the present invention, when the surface of the initial quantum dot contains the initial ligand, it is more meaningful to perform the ultraviolet irradiation treatment in the oxygen-containing atmosphere.
In some embodiments, the quantum dot may be a quantum dot core having only a core structure, or may be a quantum dot having a core-shell structure. In some embodiments, the core of the quantum dot, the core of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each independently selected from at least one of a group II-VI semiconductor compound, a group III-V semiconductor compound, and a group IV-VI semiconductor compound. Wherein the group II-VI semiconductor compounds include, but are not limited to, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe; group II-V semiconductor compounds include, but are not limited to, GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaGaGaAs, GaSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InNP, InNAs, InNSb, InAlPAs, InAlPSb; group IV-VI semiconductor compounds include, but are not limited to, SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe.
In some embodiments, the initial ligand of the surface of the initial quantum dot in the initial quantum dot thin film is a thiol-based initial ligand. The initial ligand of mercaptan is difficult to displace from the surface of the quantum dot through conventional ligand displacement, but the initial ligand of mercaptan which is difficult to remove from the surface of the quantum dot can be removed by adopting ultraviolet irradiation treatment under oxygen-containing atmosphere provided by the embodiment of the invention, and other surface ligands, particularly ligands with weak coordination capacity with the surface of the quantum dot, can be realized, so that the exchange requirements of ligands with different coordination capacities are met. In some embodiments, the thiol-based primary ligand is selected from at least one of propanethiol, n-butanethiol, hexanethiol, n-octanethiol, isooctane thiol, dodecanethiol, tert-dodecanethiol, tetradecanethiol, hexadecanethiol, octadecanethiol, and the like, but is not limited thereto.
In the embodiment of the invention, the initial ligand on the surface of the initial quantum dot in the initial quantum dot film is removed by carrying out ultraviolet irradiation treatment on the initial quantum dot film.
In the embodiment of the present invention, the ultraviolet irradiation treatment includes an ultraviolet wavelength capable of opening and cutting a covalent bond in an organic ligand. In some embodiments, the initial quantum dot film is subjected to an ultraviolet irradiation treatment under ultraviolet light having wavelengths of 254nm and 185nm to irradiate the initial quantum dots. In some embodiments, the initial quantum dot film is subjected to an ultraviolet irradiation treatment under ultraviolet light having a wavelength of 185 nm. The covalent bonds in the organic ligands can be directly opened and cut through the action of ultraviolet light with the wavelengths of 254nm and 185nm or 185nm, so that the effect of removing weak ligands on the surface is achieved.
In some embodiments, the step of subjecting the initial quantum dot thin film to ultraviolet irradiation treatment is performed under an oxygen-containing atmosphere. Namely: the ultraviolet irradiation treatment of the initial quantum dot film comprises the following specific steps: and carrying out ultraviolet irradiation treatment on the initial quantum dot film in an oxygen-containing atmosphere. On one hand, the ultraviolet light can open and cut off the covalent bond in the initial ligand, and the purpose of removing the initial quantum dot surface ligand is achieved; on the other hand, in an oxygen-containing atmosphere, the ultraviolet light beam decomposes oxygen molecules in the air to generate free oxygen, and ozone generated by combining the free oxygen and other oxygen molecules has extremely high oxidation effect on conventional organic ligands, particularly has extremely high oxidation effect on thiol initial ligands which have strong reducibility and are tightly combined with quantum dot ligands, and can quickly oxidize the strong coordination ligands, thereby playing a role in quickly removing surface strong ligands. Particularly, thiol initial ligands which are difficult to remove on the surface of the quantum dots can be removed.
Wherein, the oxygen-containing atmosphere refers to an atmosphere containing oxygen, including but not limited to an air atmosphere. Wherein, oxygen molecules in the oxygen-containing atmosphere are decomposed into free oxygen under ultraviolet irradiation treatment, and then combined with other oxygen molecules to generate ozone. Ozone has extremely strong oxidation effect on conventional organic ligands, particularly has extremely strong oxidation effect on initial thiol ligands which have strong reducibility and are tightly combined with quantum dot ligands, and can quickly oxidize the strong coordination ligands, so that the effect of quickly removing the strong ligands on the surfaces of the initial quantum dots is achieved, and the purpose of replacing the ligands with strong coordination capacity on the surfaces of the quantum dots with the ligands with weak coordination capacity is achieved.
In some embodiments, the initial quantum dot film is subjected to ultraviolet irradiation treatment under an oxygen-containing atmosphere and ultraviolet light with a wavelength of 185 nm. In this case, the ultraviolet light with a wavelength of 185nm can decompose oxygen into free oxygen, which then reacts with oxygen molecules to form ozone with a very strong oxidizing ability, thereby destroying the ligands with strong reducibility on the surface of the quantum dots.
According to the embodiment of the invention, the initial quantum dot film is subjected to ultraviolet irradiation treatment, particularly the initial quantum dot film is subjected to ultraviolet irradiation treatment in an oxygen-containing atmosphere, so that the problem that the quantum dot ligands cannot be completely exchanged depending on the strength of the ligand coordination capacity is solved, the flexibility and operability of ligand exchange with different strength of the ligand coordination capacity are obviously improved, and the requirement in the ligand exchange process is met.
In some embodiments, the initial quantum dot film is placed in an ultraviolet ozone cleaning machine for ultraviolet irradiation treatment. In some embodiments, the uv wavelength of the low pressure uv mercury lamp in the uv ozone cleaning machine is set to emit uv light containing at least 185 nm.
In some embodiments, the time for performing the ultraviolet irradiation treatment on the initial quantum dot thin film is 10min to 60 min. In this case, the initial ligands on the surface of the initial quantum dots can be effectively removed without affecting the performance of the initial quantum dots. If the ultraviolet irradiation treatment time is too short and is less than 10min, the initial ligand on the surface of the initial quantum dot may not be sufficiently removed; if the ultraviolet irradiation treatment time is too long and exceeds 60min, the quantum dots may be damaged, and particularly, in an oxygen-containing atmosphere, the irradiation treatment time is too long, the ozone content generated by ultraviolet oxidation of oxygen is too much, the quantum dots may be oxidized, the surface damage may be caused to the quantum dots, and the surface defects are introduced, so that the optical performance of the quantum dots is affected.
And after the initial quantum dot film is subjected to ultraviolet irradiation treatment, the initial ligand on the surface of the initial quantum dot falls off to form a first quantum dot. In addition, impurities may be introduced when the initial ligand is dropped during the ultraviolet irradiation treatment. If the dropped initial ligand and the impurities possibly introduced are not removed, the subsequent binding of the target ligand on the surface of the quantum dot is influenced. In particular, when the coordination ability of the initial ligand to the quantum dot is greater than that of the target ligand to the quantum dot, the binding of the target ligand to the surface of the quantum dot is seriously affected. And residual impurities can also remain in the film layer, which affects the luminescence property of the finally obtained quantum dot film. Therefore, in the embodiment of the present invention, after the step of performing the ultraviolet irradiation treatment on the initial quantum dot thin film, the obtained quantum dot thin film is subjected to a cleaning treatment to remove the initial ligand that falls off and other impurities that may be generated under the ultraviolet irradiation treatment.
In some embodiments, the method of the cleaning process is: and cleaning the initial quantum dot film subjected to ultraviolet irradiation treatment by using a polar solvent. The polar reagent can clean and remove initial ligands generated in the ultraviolet irradiation treatment process and impurities possibly introduced; but also can avoid dissolving away the quantum dot film. In some embodiments, the polar solvent is selected from organic alcohol solvents. In some embodiments, the organic alcohol reagent is selected from at least one of methanol, ethanol, isopropanol, but is not limited thereto, and is preferably ethanol, which is non-toxic and inexpensive.
In the step S02, the target ligand is added to the first quantum dot thin film, and the first ligand is bound to the surface of the first quantum dot not containing the initial ligand, thereby forming a quantum dot thin film having the target ligand bound to the surface. In the embodiment of the invention, the selection of the initial ligand is not strictly limited, and the initial ligand can be a ligand with weak coordination capacity or a ligand with strong coordination capacity, so that the bottleneck of replacing the ligand with weak coordination capacity by the conventional ligand with strong coordination capacity can be broken through. In some embodiments, the target ligand is selected from the group consisting of carboxylic acid ligands, amine ligands, phosphine oxide ligands, and phosphine ligands having a carbon number of less than or equal to 30. Particularly, when the initial ligand of the initial quantum dot in the initial quantum dot film is a thiol initial ligand; the target ligand is selected from carboxylic acid ligands, amine ligands, phosphine oxide ligands and phosphine ligands with the carbon atom number less than or equal to 30, and the thiol initial ligand with strong coordination capacity on the surface of the quantum dot can be replaced by the target ligand with weak coordination capacity by the quantum dot replacement method.
In some embodiments, after the step of adding a target ligand to the first quantum dot, the method further comprises: and cleaning the obtained quantum dots combined with the target ligand by using a polar solvent to remove excessive target ligand, so as to avoid the influence of residual target ligand on the luminescence property of the quantum dot film due to the fact that the residual target ligand enters the quantum dot film. In some embodiments, the polar solvent is selected from organic alcohol solvents. In some embodiments, the organic alcohol reagent is selected from at least one of methanol, ethanol, isopropanol, but is not limited thereto, and is preferably ethanol, which is non-toxic and inexpensive.
According to the embodiment of the invention, the organic solvent in the quantum dot film is removed through annealing treatment, and the compactness of the film is improved. In some embodiments, the annealing treatment conditions are: annealing for 1-20 min at 50-80 deg.c. If the annealing temperature is too high or the annealing time is too long, the ligand bound on the surface of the quantum dot may be affected, and even the quantum dot in the quantum dot film may be affected.
In the embodiment of the invention, the quantum dot film is deposited on a substrate at least comprising a cathode or an anode.
In some embodiments, the quantum dot thin film is deposited on at least an anode-containing substrate. In some embodiments, the anode is disposed on a substrate, which may be a rigid substrate or a flexible substrate. In some embodiments, the quantum dot film is deposited on a substrate comprising an anode, a hole functional layer, and the quantum dot film is disposed on a surface of the hole functional layer facing away from the anode. Wherein the hole function layer comprises at least one of a hole injection layer and a hole transport layer. In some embodiments, at least the anode-containing substrate includes a substrate, an anode formed on the substrate, a hole injection layer formed on a surface of the anode facing away from the substrate, and a hole transport layer formed on a surface of the hole injection layer facing away from the anode.
Furthermore, after the quantum dot film is prepared, a cathode is prepared on the quantum dot film. In some embodiments, before preparing the cathode, the method further comprises preparing an electronic function layer on the quantum dot thin film, wherein the electronic function layer comprises at least one of an electron transport layer, an electron injection layer, and a combination thereof. In some embodiments, an electron transport layer, an electron injection layer, and a cathode are sequentially prepared on the quantum dot thin film.
In some embodiments, the quantum dot thin film is deposited on at least a cathode-containing substrate. In some embodiments, the cathode is disposed on a substrate, which may be a rigid substrate or a flexible substrate. In some embodiments, the quantum dot film is deposited on a substrate comprising a cathode, an electronically functional layer, and the quantum dot film is disposed on a surface of the electronically functional layer facing away from the cathode. Wherein the electron function layer comprises at least one of the electron injection layers of the electron transport layer. In some embodiments, at least the cathode-containing substrate includes a substrate, a cathode formed on the substrate, an electron injection layer formed on a surface of the cathode facing away from the substrate, and an electron transport layer formed on a surface of the electron injection layer facing away from the cathode.
Furthermore, after the quantum dot film is prepared, an anode is prepared on the quantum dot film. In some embodiments, before preparing the anode, the method further comprises preparing a hole function layer on the quantum dot thin film, wherein the hole function layer comprises at least one of a hole injection layer and a hole transport layer. In some embodiments, a hole transport layer, a hole injection layer, and an anode are sequentially prepared on the quantum dot thin film.
The functional layers can be prepared by adopting the conventional method in the field.
As shown in fig. 2, a fourth aspect of the present invention provides a quantum dot light emitting diode, which is characterized by comprising an anode and a cathode that are oppositely arranged, and a quantum dot light emitting layer arranged between the anode and the cathode, wherein the quantum dot light emitting layer is prepared by the above method for preparing a quantum dot thin film.
According to the quantum dot light-emitting diode provided by the embodiment of the invention, the quantum dot film is prepared by the method, so that the selection of the quantum dot surface ligand in the quantum dot film has higher flexibility.
The quantum dot film is prepared by the method, and is not described herein for saving space.
The quantum dot light emitting diode in the embodiment of the present application is classified into a positive type structure quantum dot light emitting diode and an inversion type structure quantum dot light emitting diode.
In one embodiment, a positive structure quantum dot light emitting diode includes an anode and a cathode disposed opposite each other, a quantum dot light emitting layer disposed between the anode and the cathode, and the anode is disposed on a substrate. Furthermore, an electron functional layer such as an electron transport layer, an electron injection layer, a hole blocking layer and the like can be arranged between the cathode and the quantum dot light-emitting layer; a hole function layer such as a hole transport layer, a hole injection layer, and an electron blocking layer may be disposed between the anode and the quantum dot light emitting layer. In some embodiments of the positive-type structure device, the quantum dot light emitting diode includes a substrate, an anode disposed on a surface of the substrate, the hole injection layer disposed on a surface of the anode, a hole transport layer disposed on a surface of the hole injection layer, a quantum dot light emitting layer disposed on a surface of the hole transport layer, an electron transport layer disposed on a surface of the quantum dot light emitting layer, and a cathode disposed on a surface of the electron transport layer.
In one embodiment, an inversion-structured quantum dot light emitting diode includes a stacked structure of an anode and a cathode disposed opposite each other, a quantum dot light emitting layer disposed between the anode and the cathode, and the cathode is disposed on a substrate. Furthermore, an electron functional layer such as an electron transport layer, an electron injection layer, a hole blocking layer and the like can be arranged between the cathode and the quantum dot light-emitting layer; a hole function layer such as a hole transport layer, a hole injection layer, and an electron blocking layer may be disposed between the anode and the quantum dot light emitting layer. In some embodiments of the device with the inverted structure, the quantum dot light emitting diode includes a substrate, a cathode disposed on a surface of the substrate, an electron transport layer disposed on a surface of the cathode, a quantum dot light emitting layer disposed on a surface of the electron transport layer, a hole transport layer disposed on a surface of the quantum dot light emitting layer, an electron injection layer disposed on a surface of the hole transport layer, and an anode disposed on a surface of the electron injection layer.
Specifically, the selection of the anode is not limited, and ITO (indium-doped tin oxide), FTO, or ZTO may be selected, but is not limited thereto. The thickness of the anode is 30nm-110 nm.
The cathode may be selected from conventional cathode materials including, but not limited to, Al, Au, Ag, Ca, Ba, and alloys of Al, Au, Ag, Ca, Ba. The thickness of the cathode is 90nm-110 nm.
The material of the hole injection layer can be made of a hole injection material conventional in the art, and can be PEODT: PSS, CuPc, HATCN, WoOx、MoOx、CrOx、NiO、CuO、VOx、CuS、MoS2、MoSe2、WS2、WSe2But is not limited thereto. The thickness of the hole injection layer is 30nm-100 nm.
The hole transport layer can be made of hole transport materials conventional in the art, and can be TFB, PVK, PFB, TPD, TCTA, TAPC, Poly-TBP, Poly-TPD, NPB, CBP, MoO3、WoO3、NiO、CuO、V2O5And CuS, but not limited thereto. The thickness of the hole transport layer is 30nm-100 nm.
The quantum dot material in the quantum dot light emitting layer is as described above, and the thickness of the quantum dot light emitting layer is 30nm to 100 nm.
The material of the electron transport layer can be made of electron transport materials which are conventional in the field, and can be ZnO, ZnMgO, ZnInO, AlZnO, ZrOx, TiO2、SnOx、WOx、InOx、Al2O3But is not limited thereto. The thickness of the electron transmission layer is 10nm-100 nmnm。
In some embodiments, the qd-led may further comprise an encapsulation layer. The packaging layer can be arranged on the surface of a top electrode (an electrode far away from the substrate) and can also be arranged on the surface of the whole quantum dot light-emitting diode.
The following description will be given with reference to specific examples.
Example 1
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dot in the initial quantum dot film is CdxZn1-xS/CdyZn1-yAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly n-octyl mercaptan) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 30min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 185 nm. And washing the surface of the quantum dot by using an ethanol solvent to obtain the first quantum dot film without the ligand.
Adding 1ml of oleylamine ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 60 ℃ for 10min to obtain the quantum dot film with the surface being all oleylamine.
Example 2
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dot in the initial quantum dot film is CdxZn1-xS/CdyZn1-yAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly n-butylmercaptan) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 20min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 254nm and 185 nm. Washing the surface of the quantum dot by using an ethanol solvent to obtain a first quantum dot film with the ligand removedAnd (3) a membrane.
Adding 1ml of caprylic acid ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 70 ℃ for 10min to obtain the quantum dot film with the surface being completely caprylic acid.
Example 3
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dot in the initial quantum dot film is CdxZn1-xS/CdyZn1-yAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly propanethiol) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 40min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 185 nm. And washing the surface of the quantum dot by using an ethanol solvent to obtain the first quantum dot film without the ligand.
Adding 1ml of tetradecanoic acid ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 80 ℃ for 5min to obtain the quantum dot film with the surface being completely tetradecanoic acid.
Example 4
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dots in the initial quantum dot film are InP/ZnxSe1-xAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly n-octyl mercaptan) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 40min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 254nm and 185 nm. And washing the surface of the quantum dot by using an ethanol solvent to obtain the first quantum dot film without the ligand.
And adding 1ml of oleylamine ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 80 ℃ for 5min to obtain the quantum dot film with the surface being all oleylamine.
Example 5
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dots in the initial quantum dot film are InP/ZnxSe1-xAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly hexanethiol) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 50min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 185 nm. And washing the surface of the quantum dot by using an ethanol solvent to obtain the first quantum dot film without the ligand.
Adding 1ml of caprylic acid ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 80 ℃ for 5min to obtain the quantum dot film with the surface being completely caprylic acid.
Example 6
A preparation method of a quantum dot film comprises the following steps:
depositing quantum dot films (sequentially comprising a substrate, a bottom electrode, a hole injection layer, a hole transmission layer and an initial quantum dot film from bottom to top) of each functional layer, wherein the quantum dots in the initial quantum dot film are InP/ZnxSe1-xAnd S, wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and the initial ligand is mainly n-octyl mercaptan) is placed in an ultraviolet ozone cleaning machine to be subjected to ultraviolet ozone treatment for 40min, wherein the wavelength of ultraviolet light emitted by a low-pressure ultraviolet mercury lamp in the ultraviolet ozone cleaning machine is 185 nm. And washing the surface of the quantum dot by using an ethanol solvent to obtain the first quantum dot film without the ligand.
Adding 1ml of tetradecanoic acid ligand into the first quantum dot film without the ligand, washing the excessive ligand on the surface of the quantum dot by using an ethanol solvent, and annealing at the temperature of 80 ℃ for 5min to obtain the quantum dot film with the surface being completely tetradecanoic acid.
Example 7
A quantum dot light-emitting diode comprises an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and a hole injection layer and a hole transport layer arranged between the quantum dot light-emitting layer and the anode, wherein the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in the example 1, and the thickness is 60 nm; the electron transmission layer is ZnO with the thickness of 80 nm; the cathode was Al and had a thickness of 50 nm.
Example 8
A quantum dot light-emitting diode comprises an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and a hole injection layer and a hole transport layer arranged between the quantum dot light-emitting layer and the anode, wherein the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in the embodiment 2, and the thickness is 60 nm; the electron transmission layer is ZnO, and the thickness is 80 nm; the cathode was Al and had a thickness of 50 nm.
Example 9
A quantum dot light-emitting diode comprises an anode, a cathode, an electron transport layer, a hole injection layer and a hole transport layer, wherein the anode and the cathode are oppositely arranged, the electron transport layer is arranged on the anode, the hole injection layer and the hole transport layer are arranged between a quantum dot light-emitting layer and the anode, the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in example 3, and the thickness is 60 nm; the electron transmission layer is ZnO with the thickness of 80 nm; the cathode was Al and had a thickness of 50 nm.
Example 10
A quantum dot light-emitting diode comprises an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and a hole injection layer and a hole transport layer arranged between the quantum dot light-emitting layer and the anode, wherein the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in example 4, and the thickness is 60 nm; the electron transmission layer is ZnO, and the thickness is 80 nm; the cathode was Al and had a thickness of 50 nm.
Example 11
A quantum dot light-emitting diode comprises an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and a hole injection layer and a hole transport layer arranged between the quantum dot light-emitting layer and the anode, wherein the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in example 5, and the thickness is 60 nm; the electron transmission layer is ZnO with the thickness of 80 nm; the cathode was Al and had a thickness of 50 nm.
Example 12
A quantum dot light-emitting diode comprises an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and a hole injection layer and a hole transport layer arranged between the quantum dot light-emitting layer and the anode, wherein the hole transport layer is arranged adjacent to the quantum dot light-emitting layer, and the anode is arranged on a substrate. Wherein the anode is ITO with the thickness of 120 nm; PSS as a hole injection layer with the thickness of 30 nm; the hole transport layer is TFB and has the thickness of 100 nm; the quantum dot light-emitting layer is the quantum dot film prepared in example 6, and the thickness is 60 nm; the electron transmission layer is ZnO, and the thickness is 80 nm; the cathode was Al and had a thickness of 50 nm.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (18)
1. The preparation method of the quantum dot film is characterized by comprising the following steps of:
providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
and adding a target ligand into the first quantum dot film, and annealing to prepare the quantum dot film with the target ligand bonded on the surface.
2. The method for preparing a quantum dot film according to claim 1, wherein the step of performing ultraviolet irradiation treatment on the initial quantum dot film specifically comprises:
irradiating the initial quantum dots under ultraviolet light with the wavelength of 185 nm; or
And irradiating the initial quantum dots under ultraviolet light with the wavelengths of 254nm and 185 nm.
3. The method for preparing a quantum dot film according to claim 1, wherein the step of performing ultraviolet irradiation treatment on the initial quantum dot film specifically comprises:
subjecting the initial quantum dot film to ultraviolet irradiation treatment in an oxygen-containing atmosphere, and/or
And the time for carrying out ultraviolet irradiation treatment on the initial quantum dot film is 10-60 min.
4. The method for preparing a quantum dot thin film according to claim 1, wherein the step of subjecting the initial quantum dot thin film to ultraviolet irradiation further comprises: cleaning the initial quantum dot film subjected to ultraviolet irradiation treatment by using a polar solvent; and/or
The step of adding a target ligand to the first quantum dot further comprises: and (3) cleaning the obtained quantum dots combined with the target ligand by using a polar solvent.
5. The method of preparing a quantum dot thin film according to claim 4, wherein the polar solvent is selected from organic alcohol solvents.
6. The method of preparing a quantum dot film according to any one of claims 1 to 5, wherein the initial quantum dots in the initial quantum dot film have thiol-based initial ligands.
7. The method for preparing a quantum dot film according to claim 6, wherein the thiol-based initiation ligand is at least one selected from the group consisting of propanethiol, n-butanethiol, hexanethiol, n-octanethiol, isooctanethiol, dodecanethiol, tert-dodecanethiol, tetradecanethiol, hexadecanethiol, octadecanethiol, and the like.
8. The method of any one of claims 1 to 5 and 7, wherein the target ligand is selected from the group consisting of carboxylic acid ligands having 30 or less carbon atoms, amine ligands, phosphine oxide ligands, and phosphine ligands.
9. The method for preparing a quantum dot thin film according to any one of claims 1 to 5 and 7, wherein the annealing treatment conditions are as follows: annealing for 1-20 min at 50-80 deg.c.
10. A quantum dot thin film, wherein the quantum dot is prepared by the method for preparing the quantum dot thin film according to any one of claims 1 to 9.
11. A preparation method of a quantum dot light-emitting diode is characterized by at least comprising the following steps:
providing an initial quantum dot film, and carrying out ultraviolet irradiation treatment on the initial quantum dot film to obtain a first quantum dot film;
and adding a target ligand into the first quantum dot film, and annealing to prepare the quantum dot film with the target ligand bonded on the surface.
12. The method for preparing a quantum dot light-emitting diode according to claim 11, wherein the step of performing ultraviolet irradiation treatment on the initial quantum dot thin film specifically comprises:
irradiating the initial quantum dots under ultraviolet light with the wavelength of 185 nm; or
And irradiating the initial quantum dots under ultraviolet light with the wavelengths of 254nm and 185 nm.
13. The method for preparing a quantum dot light-emitting diode according to claim 11, wherein the step of performing ultraviolet irradiation treatment on the initial quantum dot thin film specifically comprises:
subjecting the initial quantum dot film to ultraviolet irradiation treatment in an oxygen-containing atmosphere, and/or
And the time for carrying out ultraviolet irradiation treatment on the initial quantum dot film is 10-60 min.
14. The method of claim 11, wherein the step of subjecting the initial quantum dot film to uv irradiation further comprises: cleaning the initial quantum dot film subjected to ultraviolet irradiation treatment by using a polar solvent; and/or
The step of adding a target ligand to the first quantum dot further comprises: and (3) cleaning the obtained quantum dots combined with the target ligand by using a polar solvent.
15. The method of any one of claims 11 to 14, wherein the initial quantum dots in the initial quantum dot thin film have thiol-based initial ligands.
16. The method of any one of claims 11 to 14, wherein the target ligand is selected from the group consisting of carboxylic acid ligands having 30 or less carbon atoms, amine ligands, phosphine oxide ligands, and phosphine ligands.
17. The method for manufacturing a quantum dot light-emitting diode according to any of claims 11 to 14, wherein the annealing treatment conditions are: annealing for 1-20 min at 50-80 deg.c.
18. A quantum dot light-emitting diode comprising an anode and a cathode which are oppositely arranged, and a quantum dot light-emitting layer arranged between the anode and the cathode, wherein the quantum dot light-emitting layer is prepared by the method for preparing the quantum dot light-emitting film according to any one of claims 1 to 9.
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