CN112349850A - Inorganic semiconductor material and preparation method thereof - Google Patents
Inorganic semiconductor material and preparation method thereof Download PDFInfo
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- CN112349850A CN112349850A CN201910724595.8A CN201910724595A CN112349850A CN 112349850 A CN112349850 A CN 112349850A CN 201910724595 A CN201910724595 A CN 201910724595A CN 112349850 A CN112349850 A CN 112349850A
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- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/14—Carrier transporting layers
- H10K50/16—Electron transporting layers
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- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
Abstract
The invention belongs to the technical field of flat plates, and particularly relates to an inorganic semiconductor material and a preparation method thereof. The invention provides an inorganic semiconductor material, which comprises: the titanium dioxide nano material and the thiol compound, wherein the thiol compound is bonded with metal atoms in the titanium dioxide nano material through sulfydryl so as to be combined on the surface of the titanium dioxide nano material. The preparation method comprises the following steps: providing a titanium dioxide nano material, a thiol compound and alcohol, mixing the titanium dioxide nano material, the thiol compound and the alcohol, and carrying out heating reaction to prepare a precursor solution; and carrying out solid-liquid separation treatment on the precursor solution to obtain the inorganic semiconductor material. The inorganic semiconductor material has good electronic transmission capability, and can improve the light-emitting performance of the quantum dot light-emitting diode on the whole.
Description
Technical Field
The invention belongs to the technical field of panel display, and particularly relates to an inorganic semiconductor material and a preparation method thereof.
Background
Quantum dot electroluminescence is a novel solid-state lighting technology, has the advantages of low cost, light weight, high response speed, high color saturation and the like, has wide development prospect, and has become one of important research directions of new generation Light Emitting Diode (LED) lighting. The light emitting mechanism of the currently studied quantum dot light emitting diode (QLED) device is: electrons injected from the cathode are transmitted into the quantum dot light-emitting layer through the electron transmission layer and are subjected to composite radiation light-emitting with the holes.
In recent years, inorganic semiconductors have been considered as a relatively hot research for electron transport layers, and among them, titanium dioxide nanomaterials are wide bandgap semiconductor materials having advantages such as quantum confinement effect, size effect, and excellent fluorescent properties, thereby attracting the attention of many researchers. Especially in the last decade, titanium dioxide nanomaterials have shown great potential for development in the fields of photocatalysis, sensors, transparent electrodes, fluorescent probes, diodes, solar cells and lasers. However, the electron transport capability of the existing titanium dioxide nano material is weak, and the recombination efficiency of electrons and holes in the quantum dot light-emitting layer is low.
Disclosure of Invention
The invention mainly aims to provide an inorganic semiconductor material, aiming at improving the electron transport capability of a titanium dioxide nano material.
Another object of the present invention is to provide a method for preparing the inorganic semiconductor material.
It is another object of the present invention to provide a quantum dot light emitting diode.
In order to achieve the above object, the present invention provides the following technical solutions:
an inorganic semiconductor material comprising: the nano-material comprises a titanium dioxide nano-material and a thiol compound, wherein the thiol compound is bonded with metal atoms in the titanium dioxide nano-material through sulfydryl so as to be combined on the surface of the titanium dioxide nano-material.
The inorganic semiconductor material provided by the invention is a titanium dioxide nano material modified by the surface of a thiol compound, the thiol compound is bonded with metal atoms in the titanium dioxide nano material by sulfydryl, the defect state existing on the surface of the titanium dioxide nano material is effectively passivated, the carrier recombination center caused by the defect state at the interface is reduced, the recombination probability of captured electrons and holes in a bulk heterojunction is reduced, the electrons and the holes are promoted to be effectively recombined in a quantum dot light emitting layer, and the carrier transmission channel constructed after surface passivation increases the transmission life of photogenerated carriers in a device, improves the electron transmission capability of the material, thereby integrally improving the light emitting performance of a quantum dot light emitting diode.
Correspondingly, the preparation method of the inorganic semiconductor material comprises the following steps:
providing a titanium dioxide nano material, a thiol compound and alcohol, mixing the titanium dioxide nano material, the thiol compound and the alcohol, and carrying out heating reaction to prepare a precursor solution;
and carrying out solid-liquid separation treatment on the precursor solution to obtain the inorganic semiconductor material.
According to the preparation method of the inorganic semiconductor material, the titanium dioxide nano material and the thiol compound are heated and reacted in alcohol, and then solid-liquid separation treatment is carried out, so that the titanium dioxide nano material is subjected to surface modification by the thiol compound, and the thiol compound is stably bonded on the surface of the titanium dioxide nano material.
Correspondingly, a quantum dot light emitting diode comprises a cathode and an anode which are oppositely arranged, a quantum dot light emitting layer arranged between the cathode and the anode, and an electron transport layer arranged between the cathode and the quantum dot light emitting layer, wherein the electron transport layer comprises the following materials: the inorganic semiconductor material or the inorganic semiconductor material prepared by the preparation method.
According to the quantum dot light-emitting diode provided by the invention, the material of the electron transport layer comprises the inorganic semiconductor material, the recombination efficiency of electrons and holes in the quantum dot light-emitting layer is high, the quantum dot light-emitting diode has good electron transport capability, and the light-emitting performance of the quantum dot light-emitting diode can be integrally improved.
Drawings
FIG. 1 is a schematic view of the connection structure of thiol compounds and titanium dioxide nanomaterials in a preferred semiconductor material according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for preparing an inorganic semiconductor material according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a quantum dot light emitting diode according to an embodiment of the present invention.
Reference numerals: the light-emitting diode comprises a substrate 1, an anode 2, a hole transport layer 3, a quantum dot light-emitting layer 4, an electron transport layer 5 and a cathode 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail 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 embodiments of the present invention, any ratio of the amounts of the components of the composition according to the description of the embodiments of the present invention may be enlarged or reduced within the scope of the disclosure of the description of the embodiments of the present invention. Specifically, the mass described in the description of the embodiments of the present invention may be a unit of weight known in the field of materials such as μ g, mg, g, kg, etc.
In order to solve the technical problem of low electron transport capability of the existing titanium dioxide nano material, the embodiment of the invention provides an inorganic semiconductor material, and the specific technical scheme is as follows:
an inorganic semiconductor material comprising: the nano-material comprises a titanium dioxide nano-material and a thiol compound, wherein the thiol compound is bonded with metal atoms in the titanium dioxide nano-material through sulfydryl so as to be combined on the surface of the titanium dioxide nano-material.
The inorganic semiconductor material provided by the embodiment of the invention is a titanium dioxide nano material modified by the surface of a thiol compound, the thiol compound is bonded with metal atoms in the titanium dioxide nano material by sulfydryl, the defect state existing on the surface of the titanium dioxide nano material is effectively passivated, the carrier recombination center caused by the defect state at the interface is reduced, the recombination probability of captured electrons and holes in bulk heterojunction is reduced, the electrons and the holes are promoted to be effectively recombined in a quantum dot light-emitting layer, the photon-generated carrier transmission life in a device is prolonged by an electron transmission channel constructed after surface passivation, the electron transmission capability of the material is improved, and the light-emitting performance of a quantum dot light-emitting diode is integrally improved.
Specifically, the titanium dioxide nano material is an n-type semiconductor material and is used as a material of an electron transport layer of the quantum dot light-emitting diode. In the embodiment of the invention, the titanium dioxide nano material is preferably a water-soluble nano material. In the later process, the metal oxide nano material is easy to dissolve in aqueous solution, has good film forming property, ensures the structural integrity of the quantum dot light-emitting diode and improves the light-emitting property of the quantum dot light-emitting device. In one embodiment, the preparation of the titanium dioxide nanomaterial comprises: providing a titanium salt, and dissolving the titanium salt in alcohol to prepare a salt solution; providing an alkali liquor, adding the alkali liquor into the salt solution for mixing, stirring at 60-90 ℃ for 4-6 hours, cooling the reaction liquid, and then separating out solid particles obtained by reaction by using a precipitator, such as ethyl acetate. The titanium salt is a precursor salt corresponding to a metal oxide which can be used as an electron transport layer, and includes but is not limited to titanium nitrate, titanium chloride, titanium sulfate, titanium bromide and the like; such alcohols include, but are not limited to, isopropanol, ethanol, propanol, butanol, methanol, and the like; the alkali solution includes, but is not limited to, ammonia, potassium hydroxide, sodium hydroxide, lithium hydroxide, ethanolamine, ethylene glycol, diethanolamine, triethanolamine, ethylenediamine, etc. Further, in the step of the salt solution, the concentration of the metal salt is 0.2-1mol/L, and when the concentration of the metal salt is lower than 0.2mol/L, the reaction rate is slow; when the concentration of the metal salt is more than 1mol/L, the reaction rate is high, and the agglomeration of the nano particles can be caused. In addition, in the step of adding the alkali liquor into the salt solution for mixing, the pH value of the mixed solution is adjusted to 12-13, the pH value is directly related to the concentration of hydroxide ions in the solution, and the generation of titanium dioxide nano materials is not facilitated when the pH value is too large or too small. Furthermore, in the step of adding the alkali liquor into the salt solution for mixing, the molar ratio of hydroxide ions of the alkali liquor to titanium ions in the salt solution is (3.5-4.5):1, so that the compact electron transport material can be obtained after subsequent high-temperature annealing. When the molar ratio of hydroxide ions to metal cations is less than 3.5:1 and the pH value is less than 12, the titanium salt is excessive and the reaction is insufficient; when the molar ratio of hydroxide ions to titanium ions is greater than 4.5:1 and the pH is greater than 13, too high a pH will result in a slow hydrolysis and polycondensation rate of the sol in the system.
Specifically, the thiol compound is used for modifying the surface of the titanium dioxide nano material. In the embodiment of the invention, the structural formula of the thiol compound is preferably HS-R-SH, and R is a hydrocarbyl or a hydrocarbyl derivative with the carbon number of 1-13. It is understood that the hydrocarbyl group is an alkane composed of C and H, such as: methyl, methylene, ethyl and the like. The thiol compound with the structural formula of HS-R-SH has the mercapto groups at two ends which can be respectively bonded with two titanium dioxide nano materials, so that the agglomeration phenomenon of the titanium dioxide nano materials is relieved, the dispersibility of the titanium dioxide nano materials is increased, and the film forming property of the inorganic semiconductor material is improved. In some embodiments, the thiol-based compound is at least one of ethanedithiol, propanedithiol, and butanedithiol.
In the embodiment of the invention, the thiol compound is bonded with the metal atom in the titanium dioxide nanomaterial through a mercapto group, the thiol compound contains two mercapto groups, as shown in fig. 1, the two mercapto groups can be bonded with the titanium atom of the same titanium dioxide at the same time, and can also be bonded with the titanium atoms of different titanium dioxides, so as to modify the surface of the titanium dioxide nanomaterial, and effectively passivate the defect state existing on the surface of the titanium dioxide nanomaterial. In some embodiments, the thiol compound is ethanedithiol, two thiol groups of a part of ethanedithiol are respectively bonded to titanium atoms of different titanium dioxide molecules, and two thiol groups of the remaining ethanedithiol are bonded to titanium atoms of the same titanium dioxide molecule. Compared with the titanium dioxide nano material, the titanium dioxide nano material modified by the surface of the thiol compound has better electron transmission capability, can be used as a good inorganic semiconductor material, and is used for improving the light emitting performance of the quantum dot light emitting diode.
In a preferred embodiment of the present invention, the molar ratio of sulfur in the thiol compound to titanium in the titanium dioxide nanomaterial in the inorganic semiconductor material is preferably (4-6):1, and within this ratio range, the thiol compound can be favorably modified on the surface of the titanium dioxide nanomaterial, so that the inorganic semiconductor material according to the embodiment of the present invention has a good electron transport ability. In some embodiments, the molar ratio of sulfur to titanium in the inorganic semiconductor material is preferably 4:1, 5:1, or 6: 1. In other embodiments, the thiol compound is ethanedithiol, and the molar ratio of ethanedithiol to titanium dioxide is (2-3): 1.
In a preferred embodiment of the present invention, the inorganic semiconductor material has a particle size of 5 to 10nm, and is excellent in dispersibility and easy to form a uniform film.
Accordingly, a method for preparing the inorganic semiconductor material, please refer to fig. 2, includes the following steps:
s01, providing a titanium dioxide nano material, a thiol compound and alcohol, mixing the titanium dioxide nano material, the thiol compound and the alcohol, and carrying out heating reaction to prepare a precursor solution;
and S02, carrying out solid-liquid separation treatment on the precursor solution to obtain the inorganic semiconductor material.
According to the preparation method of the inorganic semiconductor material provided by the embodiment of the invention, the titanium dioxide nano material and the thiol compound are heated and reacted in alcohol, and then solid-liquid separation treatment is carried out, so that the titanium dioxide nano material is subjected to surface modification by the thiol compound, and the thiol compound is stably bonded on the surface of the titanium dioxide nano material.
Specifically, in step S01, the titanium dioxide nanomaterial, the thiol compound, and the alcohol are mixed and subjected to a heating reaction. In the present embodiment, the molar ratio of sulfur to titanium of the precursor solution is preferably (4-6): 1. Within the proportion range, the thiol compound can be well modified on the surface of the titanium dioxide nano material, so that the inorganic semiconductor material provided by the embodiment of the invention has good electron transport capability. When the molar ratio of sulfur to titanium in the inorganic semiconductor material is less than 4:1, the concentration of the thiol compound is smaller and smaller along with the progress of the raw material reaction, the counter strain is slow, and even the thiol compound cannot be completely adsorbed on the surface of the titanium dioxide nano material; when the molar ratio of sulfur to titanium in the inorganic semiconductor material is greater than 6:1, the reaction proceeds too quickly and, in a subsequent high-temperature annealing step, the properties of the material are affected due to the removal of excessive thiol compounds. In some embodiments, the molar ratio of sulfur to titanium in the inorganic semiconductor material is preferably 4:1, 5:1, or 6: 1.
Preferably, in the step of performing the heating reaction, the reaction temperature is 60 to 80 ℃ and the reaction time is 2 to 4 hours. In some embodiments, the temperature of the reaction is 60, 62, 65, 66, 68, 70, 71, 73, 75, 77, 79, 80 ℃; in other embodiments, the reaction time is 2, 2.5, 2.7, 3, 3.1, 3.3, 3.5, 3.7, 4 hours; in still other embodiments, the heating reaction is accompanied by constant temperature stirring.
Specifically, in step S02, the precursor solution is subjected to solid-liquid separation treatment to separate and obtain the inorganic semiconductor material. In one embodiment, the method comprises the steps of precipitating a thiol compound surface-modified titanium dioxide nano material in a precursor solution through sedimentation treatment, collecting sediments, cleaning and drying to obtain the thiol compound surface-modified titanium dioxide nano material; wherein the sedimentation treatment can be achieved by adding a precipitant. In another embodiment, the precursor solution can be further prepared into a film to obtain a thin film. Specifically, after the precursor solution is deposited on a substrate, a thin film is prepared through annealing treatment. Further, the temperature of the high-temperature annealing is preferably 200-350 ℃, specifically 200, 220, 240, 250, 260, 290, 300, 320, 350 ℃.
Under the comprehensive action of the optimized condition parameters such as the molar ratio, the concentration, the temperature, the time and the like of the raw materials, the comprehensive performance of the inorganic semiconductor material obtained by the preparation method provided by the embodiment of the invention can be optimized.
Correspondingly, a quantum dot light emitting diode comprises a cathode and an anode which are oppositely arranged, a quantum dot light emitting layer arranged between the cathode and the anode, and an electron transport layer arranged between the cathode and the quantum dot light emitting layer, wherein the electron transport layer comprises the following materials: the inorganic semiconductor material described above.
According to the quantum dot light-emitting diode provided by the invention, the material of the electron transport layer comprises the inorganic semiconductor material, the recombination efficiency of electrons and holes in the quantum dot light-emitting layer is high, the quantum dot light-emitting diode has good electron transport capability, and the light-emitting performance of the quantum dot light-emitting diode can be integrally improved.
In some embodiments, the electron transport layer has a thickness of 20-60 nm.
In the embodiment of the present invention, each quantum dot light emitting diode includes an anode, a hole transport layer, a quantum dot light emitting layer, an electron transport layer, and a cathode, which are sequentially stacked, and it can be understood that, in addition to the hole transport layer, the quantum dot light emitting layer, and the electron transport layer, the quantum dot light emitting diode further includes other film layer structures, for example: a substrate, a hole injection layer, an electron injection layer, etc. In the embodiment of the present invention, the qd-led may have a positive structure or an inverse structure, wherein the positive structure and the inverse structure are different mainly in that: an anode of a positive structure is connected with the substrate and is arranged on the surface of the substrate in a laminated mode by taking the anode as a bottom electrode; the cathode of the inversion structure is connected with the substrate, and is used as a bottom electrode to be stacked on the surface of the substrate.
As shown in fig. 3, the quantum dot light emitting diode is a positive type structure, and includes a substrate 1, an anode 2, a hole transport layer 3, a quantum dot light emitting layer 4, an electron transport layer 5, and a cathode 6, which are stacked in this order.
In an embodiment of the invention, the substrate is selected to be a glass sheet.
In the embodiment of the invention, the anode is selected from ITO.
In embodiments of the present invention, hole transport materials conventional in the art may be used, including but not limited to TFB, PVK, Poly-TPD, TCTA, PEDOT: PSS, CBP, etc., or any combination thereof, as well as other high performance hole transport materials. In the embodiment of the present invention, the thickness of the hole transport layer is preferably 20 to 60nm, and more preferably 50 nm.
In the embodiment of the invention, the quantum dot light-emitting layer has the characteristics of wide and continuous distribution of excitation spectrum, high stability of emission spectrum and the like, and is selected as an oil-soluble quantum dot, and the method comprises the following steps: binary phase, ternary phase and quaternary phase quantum dots. Wherein the binary phase quantum dots include but are not limited to CdS, CdSe, CdTe, InP, AgS, PbS, PbSe, HgS, and the ternary phase quantum dots include but are not limited to ZnXCd1-XS、CuXIn1-XS、ZnXCd1-XSe、ZnXSe1-XS、ZnXCd1-XTe、PbSeXS1-XThe quaternary phase quantum dots include but are not limited to ZnXCd1-XS/ZnSe、CuXIn1-XS/ZnS、ZnXCd1-XSe/ZnS、CuInSeS、ZnXCd1-XTe/ZnS、PbSeXS1-Xand/ZnS. In the embodiment of the invention, the quantum dot light-emitting layer can be any one of red, green and blue quantum dots, or yellow quantum dots. In the embodiment of the present invention, the thickness of the quantum dot light emitting layer is preferably 20 to 60 nm.
In the embodiment of the present invention, the electron transport layer is a thin film layer made of the inorganic semiconductor material provided in the embodiment of the present invention, and the preparation method is a spin coating process, including but not limited to, drop coating, spin coating, dipping, coating, printing, evaporation, and the like. In some embodiments, a substrate on which a quantum dot light emitting layer is spin-coated is placed on a spin coater, a precursor solution with a certain concentration is prepared to spin-coat a film, the thickness of the light emitting layer is controlled to be about 20-60nm by adjusting the concentration of the solution, the spin-coating speed (preferably, the rotation speed is between 2000-6000 rpm) and the spin-coating time, and then a high-temperature annealing film is performed. The step can be annealing in air or in nitrogen atmosphere, and the annealing atmosphere is selected according to actual needs.
In the embodiment of the invention, the cathode is selected from metallic silver or metallic aluminum. In some embodiments, the cathode is a layered metallic silver or metallic aluminum with a thickness of 15-30 nm; in other embodiments, the cathode is a nano Ag wire or a Cu wire.
Correspondingly, the embodiment of the invention also provides a preparation method of the quantum dot light-emitting diode with the structure shown in fig. 3, which comprises the following steps:
1) providing a substrate, and depositing an anode, a hole transport layer and a quantum dot light emitting layer on the substrate in sequence;
2) preparing the precursor solution, continuously coating the precursor solution on the quantum dot light-emitting layer, and performing high-temperature annealing at the temperature of 200-350 ℃ to prepare an electron transport layer;
3) continuously vacuum evaporating an electron cathode on the electron transport layer;
4) and packaging the obtained QLED.
In some embodiments, the vacuum evaporation speed of step 3) is about 0.01-0.5 nm/s.
In other embodiments, the anode is selected to be an ITO film layer.
In the embodiment of the present invention, the encapsulation process in step 4) may be implemented by a conventional machine, or may be implemented by manual encapsulation. In some embodiments, to ensure device stability, the packaging process environment has an oxygen content and a water content of less than 0.1 ppm.
Further, in order to obtain the inorganic semiconductor material with high quality, the ITO film layer needs to be subjected to a pretreatment process, and the basic specific treatment steps include: cleaning the whole piece of ITO conductive glass with a cleaning agent to primarily remove stains on the surface, then sequentially carrying out ultrasonic cleaning in deionized water, acetone, absolute ethyl alcohol and deionized water for 20min respectively to remove impurities on the surface, and finally blowing the ITO conductive glass with high-purity nitrogen to dry the ITO conductive glass.
In order to make the above details and operations of the present invention clearly understood by those skilled in the art, and to make the progress of the inorganic semiconductor material, the method for preparing the same, and the quantum dot light emitting diode according to the embodiments of the present invention more obvious, the embodiments of the present invention are illustrated below by way of examples.
Example 1
The embodiment prepares an inorganic semiconductor material, which is a titanium dioxide nano material modified by butanedithiol surface, and the specific process flow is as follows:
1. weighing titanium sulfate, adding the titanium sulfate into 50mL of propanol, and stirring and dissolving at 80 ℃ to form a salt solution with the total concentration of 0.5M; weighing potassium hydroxide, and dissolving the potassium hydroxide in 10mL of propanol to prepare alkali liquor; then, according to OH-And Ti4+The molar ratio of the alkali solution to the salt solution is 4.5:1, a mixed solution with the pH value of 12 is formed, and then the mixed solution is stirred for 4 hours at the temperature of 80 ℃ to obtain a uniform and transparent reaction solution; then, after the reaction liquid is cooled, octane is used for precipitation, after centrifugation, a small amount of ethanol is used for dissolution, the precipitation and dissolution steps are repeated for 3 times, and drying is carried out to prepare TiO2A nanomaterial; (ii) a
2. Adding the titanium dioxide nano material into 30mL of propanol to form a solution with the total concentration of 1M; then adding butanedithiol, and continuing stirring at 80 ℃ for 2h to obtain a uniform and transparent precursor solution; wherein the molar ratio of the titanium dioxide to the butanedithiol is 1: 3;
3. and after the precursor solution is cooled, spin-coating the precursor solution on the treated ITO by using a spin coater, and annealing at 300 ℃.
Example 2
The embodiment prepares an inorganic semiconductor material, which is a titanium dioxide nano material modified by ethanedithiol surface, and the specific process flow is as follows:
1. weighing titanium sulfate, adding the titanium sulfate into 50mL of ethanol, and stirring and dissolving at 70 ℃ to form a salt solution with the total concentration of 0.8M; weighing sodium hydroxide, and dissolving the sodium hydroxide in 10mL of ethanol to prepare alkali liquor; then, according to OH-And Ti4+The molar ratio of alkali solution to salt solution is 4.8:1, mixed solution with pH of 13 is formed, and then the mixed solution is stirred for 4 hours at 70 ℃ to obtain uniform and transparent reaction solution; then, after the reaction liquid is cooled, pentane is used for precipitation, after centrifugation, a small amount of ethanol is used for dissolution, and the weight is heavyRe-precipitation and dissolution step for 3 times, drying and preparing TiO2A nanomaterial;
2. adding the titanium dioxide nano material into 30mL of ethanol to form a solution with the total concentration of 1M; then adding ethanedithiol, and continuously stirring at 70 ℃ for 2h to obtain a uniform and transparent precursor solution; wherein the molar ratio of the titanium dioxide to the ethanedithiol is 1: 2.5;
3. and after the precursor solution is cooled, spin-coating the precursor solution on the treated ITO by using a spin coater, and annealing at 300 ℃.
Example 3
The embodiment prepares an inorganic semiconductor material, which is a titanium dioxide nano material modified by a propanedithiol surface, and the specific process flow is as follows:
1. weighing titanium nitrate, adding the titanium nitrate into 50mL of methanol, and stirring and dissolving at 60 ℃ to form a salt solution with the total concentration of 1M; weighing lithium hydroxide, and dissolving the lithium hydroxide in 10mL of methanol to prepare alkali liquor; then, according to OH-And Ti4+The molar ratio of alkali solution to salt solution is 4.7:1, mixed solution with pH of 12 is formed, and then the mixed solution is stirred for 4 hours at the temperature of 60 ℃, so that uniform and transparent reaction solution is obtained; then, after the reaction liquid is cooled, octane is used for precipitation, after centrifugation, a small amount of ethanol is used for dissolution, the precipitation and dissolution steps are repeated for 3 times, and drying is carried out to prepare TiO2A nanomaterial; (ii) a
2. Adding the titanium dioxide nano material into 30mL of methanol to form a solution with the total concentration of 1M; then adding propanedithiol, and continuing stirring for 2h at 60 ℃ to obtain a uniform and transparent precursor solution; wherein the molar ratio of the titanium dioxide to the propanedithiol is 1: 3;
3. and after the precursor solution is cooled, spin-coating the precursor solution on the treated ITO by using a spin coater, and annealing at 300 ℃.
Example 4
A quantum dot light-emitting diode comprises a laminated structure of an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transmission layer arranged between the cathode and the quantum dot light-emitting layer, and an electron transmission layer arranged at the anodeAnd the anode is arranged on the substrate. Wherein the substrate is made of glass sheet, the anode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of TiO modified by butanedithiol2The cathode is made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing an ITO substrate, preparing a hole transport layer on the ITO substrate,
depositing a quantum dot light emitting layer on the hole transport layer;
depositing the precursor solution obtained in the method of example 1 on the quantum dot light-emitting layer, and annealing at 250 ℃ to prepare an electron transport layer;
a cathode on the electron transport layer.
Example 5
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. Wherein the substrate is made of glass sheet, the anode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of ethanedithiol-modified TiO2The cathode is made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing an ITO substrate, and preparing a hole transport layer on the ITO substrate;
depositing a quantum dot light emitting layer on the hole transport layer;
preparing a precursor solution obtained by depositing the method in the embodiment 2 on the quantum dot light-emitting layer, and annealing at 250 ℃ to prepare an electron transport layer;
preparing a cathode on the electron transport layer.
Example 6
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. Wherein the substrate is made of glass sheet, the anode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of TiO modified by propanedithiol2The cathode is made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing an ITO substrate, and preparing a hole transport layer on the ITO substrate;
depositing a quantum dot light emitting layer on the hole transport layer;
preparing a precursor solution obtained by depositing the method in the embodiment 3 on the quantum dot light-emitting layer, and annealing at 250 ℃ to prepare an electron transport layer;
preparing a cathode on the electron transport layer.
Example 7
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the cathode is arranged on a substrate. Wherein the substrate is made of glass sheet, the cathode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of butanedithiol modified TiO2The nano material and the anode are made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing a cathode substrate, depositing the precursor solution obtained in the method of the embodiment 1 on the cathode substrate, and annealing at 250 ℃ to prepare an electron transport layer;
preparing a quantum dot light-emitting layer on the electron transport layer, and preparing a hole transport layer on the quantum dot light-emitting layer;
an anode is prepared on the hole transport layer.
Example 8
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the cathode is arranged on a substrate. Wherein the substrate is made of glass sheet, the cathode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of ethanedithiol-modified TiO2The nano material and the anode are made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing a cathode substrate, depositing the precursor solution obtained in the method of the embodiment 2 on the cathode substrate, and annealing at 250 ℃ to prepare an electron transport layer;
preparing a quantum dot light-emitting layer on the electron transport layer, and preparing a hole transport layer on the quantum dot light-emitting layer;
an anode is prepared on the hole transport layer.
Example 9
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the cathode is arranged on a substrate. Wherein the substrate is made of glass sheet, the cathode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of TiO modified by propanedithiol2The nano material and the anode are made of Al.
The preparation method of the quantum dot light-emitting diode comprises the following steps:
providing a cathode substrate, depositing the precursor solution obtained in the method of the embodiment 3 on the cathode substrate, and annealing at 250 ℃ to prepare an electron transport layer;
preparing a quantum dot light-emitting layer on the electron transport layer, and preparing a hole transport layer on the quantum dot light-emitting layer;
an anode is prepared on the hole transport layer.
Comparative example 1
A quantum dot light-emitting diode comprises a laminated structure of 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 cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. Wherein the substrate is made of glass sheet, the anode is made of ITO substrate, the hole transport layer is made of TFB, and the electron transport layer is made of commercial TiO2Material (available from Sigma) and cathode material was Al.
The performance of the electron transport films prepared in examples 1 to 3, the electron transport film prepared in comparative example 1, the quantum dot light emitting diodes prepared in examples 4 to 9 and comparative example 1 was tested, and the test indexes and the test method were as follows:
(1) electron mobility: testing the current density (J) -voltage (V) of the quantum dot light-emitting diode, drawing a curve relation diagram, fitting a Space Charge Limited Current (SCLC) region in the relation diagram, and then calculating the electron mobility according to a well-known Child, s law formula:
J＝(9/8)εrε0μeV2/d3
wherein J represents current density in mAcm-2；εrDenotes the relative dielectric constant,. epsilon0Represents the vacuum dielectric constant; mu.seDenotes the electron mobility in cm2V-1s-1(ii) a V represents the drive voltage, in units of V; d represents the film thickness in m.
(2) Resistivity: the resistivity of the electron transport film is measured by the same resistivity measuring instrument.
(3) External Quantum Efficiency (EQE): measured using an EQE optical test instrument.
Note: the electron mobility and resistivity were tested as single layer thin film structure devices, namely: cathode/electron transport film/anode. The external quantum efficiency test is the QLED device, namely: anode/hole transport film/quantum dot/electron transport film/cathode, or cathode/electron transport film/quantum dot/hole transport film/anode.
The test results are shown in table 1 below:
TABLE 1
As can be seen from table 1 above, examples 1 to 3 of the present invention provided electron transport films of titanium dioxide nanomaterial and thiol compound, the resistivity of which was significantly lower than that of the electron transport film in comparative example 1, and the electron mobility of which was significantly higher than that of the electron transport film in comparative example 1.
The external quantum efficiency of the quantum dot light-emitting diode (the electron transport layer is made of the titanium dioxide nanomaterial and the thiol compound) provided by the embodiments 4-9 of the invention is obviously higher than that of the quantum dot light-emitting diode in the comparative example 1, which shows that the quantum dot light-emitting diode obtained by the embodiments has better luminous efficiency.
It is noted that the embodiments provided by the present invention all use blue light quantum dots CdXZn1-XS/ZnS is used as a material of a luminescent layer, is based on that a blue light luminescent system uses more systems (the blue light quantum dot luminescent diode has more reference value because high efficiency is difficult to achieve), and does not represent that the invention is only used for the blue light luminescent system.
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 (12)
1. An inorganic semiconductor material, comprising: the nano-material comprises a titanium dioxide nano-material and a thiol compound, wherein the thiol compound is bonded with metal atoms in the titanium dioxide nano-material through sulfydryl so as to be combined on the surface of the titanium dioxide nano-material.
2. The inorganic semiconductor material according to claim 1, wherein the thiol compound has a formula of HS-R-SH, and R is a hydrocarbon group or a hydrocarbon group derivative having a carbon number of 1 to 13.
3. The inorganic semiconductor material according to claim 1, wherein the thiol compound is at least one of ethanedithiol, propanedithiol, and butanedithiol.
4. The inorganic semiconductor material of claim 1, wherein the titanium dioxide nanomaterial is a water-soluble nanomaterial.
5. The inorganic semiconductor material according to any one of claims 1 to 4, wherein the molar ratio of the sulfur of the thiol compound to the titanium of the titanium dioxide nanomaterial in the inorganic semiconductor material is (4-6): 1.
6. A preparation method of an inorganic semiconductor material is characterized by comprising the following steps:
providing a titanium dioxide nano material, a thiol compound and alcohol, mixing the titanium dioxide nano material, the thiol compound and the alcohol, and carrying out heating reaction to prepare a precursor solution;
and carrying out solid-liquid separation treatment on the precursor solution to obtain the inorganic semiconductor material.
7. The method according to claim 6, wherein the molar ratio of the sulfur of the thiol compound to the titanium of the titanium dioxide nanomaterial in the precursor solution is (4-6): 1.
8. The method according to claim 6, wherein the heating reaction is carried out at a reaction temperature of 60 to 80 ℃ for 2 to 4 hours.
9. The process according to any one of claims 6 to 8, wherein the thiol compound has the formula HS-R-SH, R being a hydrocarbon group or a hydrocarbon derivative having a carbon number of 1 to 13.
10. The production method according to any one of claims 6 to 8, wherein the thiol compound is at least one of ethanedithiol, propanedithiol, and butanedithiol.
11. A quantum dot light emitting diode comprising a cathode and an anode disposed opposite to each other, a quantum dot light emitting layer disposed between the cathode and the anode, and an electron transport layer disposed between the cathode and the quantum dot light emitting layer, wherein the electron transport layer is made of a material comprising: the inorganic semiconductor material according to any one of claims 1 to 5, or the inorganic semiconductor material produced by the production method according to any one of claims 6 to 10.
12. The qd-led of claim 11, wherein the electron transport layer has a thickness of 20 nm to 60 nm.
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| CN113838990A (en) * | 2021-09-26 | 2021-12-24 | 北京京东方技术开发有限公司 | Quantum dot light-emitting device, manufacturing method thereof and display device |
| CN114242923A (en) * | 2021-11-12 | 2022-03-25 | 华南理工大学 | Method for improving performance of electroluminescent device by modifying indium phosphide quantum dots through thiol compound interface |
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