Low-cost macro-quantity preparation method of defect-state molybdenum oxide quantum dots and electrochromism application

Abstract

The invention discloses a low-cost macro preparation method of defect-state molybdenum oxide quantum dots and electrochromism application, molybdenum disulfide (MoS2) powder is added into a mixed solvent of a hydrogen peroxide reagent and ethanol, after uniform stirring, the mixture is placed in a high-speed shear emulsifying machine for treatment, then centrifugation is performed, and supernate is taken to obtain a defect-state molybdenum oxide quantum dot solution. The film prepared from the quantum dot solution is combined with a patterned electrode to obtain an integrated electrochromic device with an extremely simple structure, and the integrated electrochromic device is expected to be applied to the field of energy-saving display. The preparation cost of the electrochromic material and the device is effectively reduced, and the yield of the molybdenum oxide quantum dots is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of defective molybdenum oxide quantum dots, and in particular to a low-cost, large-scale preparation method of defective molybdenum oxide quantum dots and electrochromic applications. Background Art

[0002] Electrochromism is a process in which the color and transmittance of a material undergo reversible changes under the control of low voltage. Electrochromic materials and devices are widely used. For example, electrochromic glass can be used in smart windows of buildings or cars. By adjusting the solar radiation entering the room or car on demand, heating and lighting can be intelligently controlled to achieve energy conservation and emission reduction. In addition, electrochromic materials combined with patterned processing technology can be applied to the display field to display text or image information through changes in the color of the material itself. Electrochromic display technology overcomes the shortcomings of high energy consumption of common electronic display screens, has the characteristics of low voltage drive and open circuit memory, and is particularly suitable for static displays. Its low energy consumption advantage not only conforms to the concept of contemporary green and environmental protection development, but also improves the safety of users.

[0003] Molybdenum oxide is an inorganic electrochromic material, which can produce significant color changes with the embedding and de-embedding process of small-sized cations (such as hydrogen ions, lithium ions, etc.), but its electrochromic performance is still difficult to meet practical needs. The preparation process of existing defective quantum dot materials is complicated and costly, which is not conducive to the popularization of electrochromic products in the civilian field. Therefore, there is a lack of a simple and efficient large-scale preparation process for electrochromic molybdenum oxide quantum dots. At the same time, the structure of existing electrochromic devices is relatively complex, and the preparation process is relatively cumbersome. How to simplify the preparation process of quantum dot materials and prepare them into electrochromic devices through a relatively simple method is still a problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention provides a low-cost large-scale preparation method of defective molybdenum oxide quantum dots and electrochromic application. The present invention effectively reduces the cost of the material preparation process and significantly improves the yield of molybdenum oxide quantum dots.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A low-cost, large-scale preparation method for defective molybdenum oxide quantum dots comprises mixing hydrogen peroxide reagent (30% aqueous solution) with ethanol to form a mixed solvent, and then adding molybdenum disulfide (MoS 2 ) powder, stirred evenly and placed in a high-speed shear emulsifier for treatment, and then centrifuged to obtain the supernatant to obtain a defective molybdenum oxide quantum dot solution.

[0007] The hydrogen peroxide reagent is an aqueous solution with a mass fraction of 30%, and the volume ratio of hydrogen peroxide to ethanol is between 1:3 and 1:9.

[0008] The addition amount of the molybdenum disulfide powder and the hydrogen peroxide reagent in the mixed solvent is maintained at 0.1 g / mL.

[0009] The shearing treatment time in the high-speed shearing emulsifier is between 1 hour and 3 hours.

[0010] The centrifugal speed of the centrifugal treatment is between 2500 - 4000 r / min.

[0011] The average size of the molybdenum oxide quantum dots is about 5 nanometers.

[0012] Application of the defective molybdenum oxide quantum dot solution in the field of electrochromics. The synthesized defective molybdenum oxide quantum dot solution is uniformly coated on the surface of the substrate by a certain method. After natural drying or low-temperature drying, an integrated electrochromic device is obtained.

[0013] The processing of the substrate is as follows:

[0014] Patterned electrodes are processed on the flat surface of the substrate according to the content of the display information, and the electrodes are not electrically connected to facilitate applying a voltage by connecting a power supply.

[0015] Laser etching technology is used to perform patterning processing on the surfaces of indium tin oxide (ITO) glass and fluorine-doped tin oxide (FTO) glass to divide them into multiple independent regions;

[0016] Or a gold electrode is deposited on substrates such as PET plastic film and glass by an evaporation coating process in combination with a mask template with a hollow pattern.

[0017] The certain method refers to a liquid-phase film-forming method such as drop coating or spraying, and the temperature range for low-temperature drying is 25 - 80 °C to avoid crystallization of the obtained molybdenum oxide.

[0018] The integrated electrochromic device can reversibly switch between the colored state and the faded state, and its transmittance is continuously adjustable dynamically.

[0019] Advantages of the present invention:

[0020] 1) The present invention is a green and non-toxic solution system, without using organic solvents harmful to the environment and corrosive liquids such as strong acids and strong alkalis, meeting the development requirements of green chemistry.

[0021] 2) The synthesis process flow of the defective molybdenum oxide quantum dots in the present invention is simple. There are two main processing forces during the preparation process. On the one hand, the layered structure of MoS 2The raw materials are easily peeled off under the action of mechanical shear force to form nanomaterials with defect states. On the other hand, the chemical oxidation of hydrogen peroxide further reduces the material size and promotes the formation of defect-state molybdenum oxide quantum dots due to the substitution of sulfur atoms by oxygen atoms. The present invention effectively reduces the cost in the material preparation process and significantly improves the yield of molybdenum oxide quantum dots. This mechanochemical process only requires operations such as stirring, shearing, and centrifugation, with mild conditions (room temperature and atmospheric pressure), low raw material and process costs, and is suitable for large-scale production.

[0022] 3) The integrated electrochromic device designed and prepared in the present invention has the advantages of simple structure and easy preparation. The integrated electrochromic device has a high contrast between the colored state and the faded state, and can maintain the colored state for a long time in the power-off state, and is expected to be applied in the field of energy-saving displays. Description of the Drawings

[0023] Figure 1 It is a working principle diagram of the integrated electrochromic device.

[0024] Figure 2 It is a transmission electron microscope photograph of the defect-state molybdenum oxide quantum dots.

[0025] Figure 3 It is a size distribution diagram of the defect-state molybdenum oxide quantum dots.

[0026] Figure 4 It is the transmittance spectrum of the integrated electrochromic device in the colored state and the faded state.

[0027] Figure 5 It is the transmittance change curve of the integrated electrochromic device switching between the colored state and the faded state. Detailed Embodiments

[0028] The present invention will be further described in detail below with reference to the drawings.

[0029] Example 1:

[0030] (1) Take 70 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker, and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder, and add it to the continuously stirred mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2 is evenly dispersed.

[0031] (2) After MoS 2 is evenly dispersed, put the liquid into a high-speed shear emulsifier and process for 2 hours, and use the water bath cooling method to stabilize the temperature of the sheared liquid near room temperature.

[0032] (3) Put the solution after shearing treatment into a centrifuge and centrifuge it at a speed of 3500 r / min for 30 min. Take the supernatant to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0033] (4) Ultrasonic clean the FTO glass in a special cleaning solution for 15 minutes, then ultrasonic clean it with deionized water for 15 minutes, and finally ultrasonic clean it with ethanol for 15 minutes. After drying, a clean FTO glass can be obtained. Patterned electrodes are etched on the cleaned FTO conductive glass to divide the conductive layer into multiple independent non-conducting regions.

[0034] (5) Take 400 μL of the prepared defective molybdenum oxide quantum dot solution and drop-coat it on the surface of the laser-etched FTO glass. Wait for it to dry naturally to obtain an integrated electrochromic device.

[0035] Example 2:

[0036] (1) Take 90 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder and add it to the continuously stirred aforementioned mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2 is evenly dispersed.

[0037] (2) After MoS 2 is evenly dispersed, put the liquid into a high-speed shear emulsifier and process it for 3 hours. Use the water bath cooling method to keep the temperature of the sheared liquid near room temperature.

[0038] (3) Put the solution after shearing treatment into a centrifuge and centrifuge it at a speed of 2500 r / min for 30 min. Take the supernatant to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0039] (4) Ultrasonic clean the FTO glass in a special cleaning solution for 15 minutes, then ultrasonic clean it with deionized water for 15 minutes, and finally ultrasonic clean it with ethanol for 15 minutes. After drying, a clean FTO glass can be obtained. Patterned electrodes are etched on the cleaned FTO conductive glass to divide the conductive layer into multiple independent non-conducting regions.

[0040] (5) Take 600 μL of the prepared defective molybdenum oxide quantum dot solution and drop-coat it on the surface of the laser-etched FTO glass. Dry it at 80 °C to obtain an integrated electrochromic device.

[0041] Example 3:

[0042] (1) Take 30 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker, and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder, and add it to the continuously stirred mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2 is evenly dispersed.

[0043] (2) After MoS 2 is evenly dispersed, put the liquid into a high-speed shear emulsifier and process for 1 hour. Use the water bath cooling method to keep the temperature of the sheared liquid stable near room temperature.

[0044] (3) Put the solution after shear treatment into a centrifuge and centrifuge at a speed of 4000 r / min for 30 min. Take the supernatant to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0045] (4) Ultrasonic clean the FTO glass in a special cleaning solution for 15 minutes, then ultrasonic clean it with deionized water for 15 minutes, and finally ultrasonic clean it with ethanol for 15 minutes. After drying, a clean FTO glass can be obtained. Use a laser to etch a patterned electrode on the cleaned FTO conductive glass, so that the conductive layer is divided into multiple non-conductive independent regions.

[0046] (5) Take 10 ml of the prepared defective molybdenum oxide quantum dot solution and spray it on the surface of the laser-etched FTO glass. Keep the temperature constant at 50 °C during the spraying process. After spraying, an integrated electrochromic device is obtained.

[0047] Example 4:

[0048] (1) Take 50 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker, and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder, and add it to the continuously stirred mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2 is evenly dispersed.

[0049] (2) After MoS 2 is evenly dispersed, put the liquid into a high-speed shear emulsifier and process for 2 hours. Use the water bath cooling method to keep the temperature of the sheared liquid stable near room temperature.

[0050] (3) Put the solution after shear treatment into a centrifuge and centrifuge at a speed of 3500 r / min for 30 min. Take the supernatant to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0051] (4) Ultrasonically clean the FTO glass in a special cleaning solution for 15 minutes, then ultrasonically clean it with deionized water for 15 minutes, and finally ultrasonically clean it with ethanol for 15 minutes. After drying, a clean FTO glass can be obtained. Patterned electrodes are etched on the cleaned FTO conductive glass using a laser, dividing the conductive layer into multiple non-conductive independent regions.

[0052] (5) Take 10 milliliters of the prepared defective molybdenum oxide quantum dot solution and spray it on the surface of the laser-etched FTO glass. Wait for it to dry naturally to obtain an integrated electrochromic device.

[0053] Example 5:

[0054] (1) Take 70 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder and add it to the continuously stirred above-mentioned mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2 is evenly dispersed.

[0055] (2) After MoS 2 is evenly dispersed, put the liquid into a high-speed shear emulsifier and process it for 2 hours. Use a water bath cooling method to keep the temperature of the sheared liquid near room temperature.

[0056] (3) Put the sheared solution into a centrifuge and centrifuge it at a speed of 3500 r / min for 30 min. Take the supernatant to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0057] (4) Ultrasonically clean the ITO glass in a special cleaning solution for 15 minutes, then ultrasonically clean it with deionized water for 15 minutes, and finally ultrasonically clean it with ethanol for 15 minutes. After drying, a clean ITO glass can be obtained. Patterned electrodes are etched on the cleaned ITO conductive glass using a laser, dividing the conductive layer into multiple non-conductive independent regions.

[0058] (5) Take 10 milliliters of the prepared defective molybdenum oxide quantum dot solution and spray it on the surface of the laser-etched ITO glass. Dry it at a low temperature under the condition of 25 °C to obtain an integrated electrochromic device.

[0059] Example 6:

[0060] (1) Take 70 ml of ethanol and 10 ml of hydrogen peroxide (30% aqueous solution) in a clean beaker and stir for 5 minutes on a magnetic stirrer to obtain a mixed solvent. Weigh 1 g of MoS 2 powder and add it to the continuously stirred above-mentioned mixed solvent in 4 portions at intervals of 3 minutes. After all additions, stir for another 10 minutes until MoS 2Evenly dispersed.

[0061] (2) MoS 2 After being evenly dispersed, the liquid is put into a high-speed shear emulsifier and processed for 2 hours, and the temperature of the sheared liquid is stabilized near room temperature by means of water bath cooling.

[0062] (3) The sheared solution is put into a centrifuge and centrifuged at a speed of 3500 r / min for 30 min. The supernatant is taken to obtain a dark blue defective molybdenum oxide quantum dot solution.

[0063] (4) After the PET flexible plastic film is cleaned, a gold electrode is evaporated on the surface of the PET through an evaporation coater, and the required pattern is obtained by using a mask. The gold electrodes form independent non-conductive regions.

[0064] (5) 400 microliters of the prepared defective molybdenum oxide quantum dot solution is dropped onto the surface of the PET film with gold electrodes and left to dry naturally to obtain an integrated electrochromic device.

[0065] Defective molybdenum oxide quantum dots are a type of functional material with extremely small sizes, with diameters in the range of 2 - 10 nanometers, and have excellent optical properties. Due to various physical effects such as quantum size effect and surface effect, defective molybdenum oxide quantum dots have excellent electrochemical properties and abundant reactive sites, and can significantly improve the electrochromic performance of molybdenum oxide.

[0066] Figure 1 is the working principle diagram of the integrated electrochromic device. As can be seen from Figure 1 it, the structure of the integrated electrochromic device from bottom to top includes a substrate, electrodes on the left and right sides, and a thin film prepared from the defective molybdenum oxide quantum dot solution.

[0067] Before applying voltage, hydrogen ions are evenly distributed in the molybdenum oxide quantum dot film, and the whole thin film is uniformly light blue;

[0068] After applying voltage, hydrogen ions are concentrated on the left side (near the negative electrode) of the molybdenum oxide quantum dot film. At this time, the molybdenum oxide quantum dot film in the negative electrode region is in a dark blue colored state, while the molybdenum oxide quantum dot film in the positive electrode region is in a colorless and transparent faded state.

[0069] Figure 2 is the transmission electron microscope photo of the defective molybdenum oxide quantum dots. As can be seen from Figure 2 it, the size of the molybdenum oxide prepared in the present invention is relatively uniform, and the molybdenum oxide obtained by this mechanochemical method is less than 10 nanometers.

[0070] Figure 3 is the size distribution diagram of the defective molybdenum oxide quantum dots. As can be seen from Figure 3It can be seen that the average size of the molybdenum oxide quantum dots prepared by the present invention is about 5 nanometers, which meets the definition of quantum dots and has the characteristics of deep color in the colored state and high transparency in the bleached state of the device.

[0071] Figure 4 It is the transmittance spectrum of the integrated electrochromic device in the colored state and the bleached state, where the abscissa is the wavelength of light and the ordinate is the transmittance of light with the corresponding wavelength.

[0072] It can be seen from Figure 4 that the electrochromic device is highly transparent in the bleached state, and the transmittance in the visible light band is greater than 80%; the transmittance of the device decreases sharply in the colored state, and the maximum transmittance modulation reaches 85.9%; its electrochromic mechanism is that hydrogen ions and electrons are double-embedded in the defect state molybdenum oxide quantum dots under an external electric field to promote the coloring of the device, and then hydrogen ions and electrons are double-extracted from the molybdenum oxide quantum dots after applying a reverse electric field to fade the device.

[0073] Therefore, the integrated electrochromic device prepared by the present invention has the advantages of excellent coloring effect and high contrast.

[0074] Figure 5 It is the transmittance change curve of the integrated electrochromic device switching between the colored state and the bleached state. The abscissa is time and the ordinate is the real-time transmittance. It can be seen from Figure 5 that the electrochromic device can be reversibly switched between the colored state and the bleached state, and its transmittance is dynamically and continuously adjustable. Due to the enhanced ion transport ability of the defect state molybdenum oxide quantum dots, the integrated electrochromic device prepared by the present invention has good reversible color change stability.

Claims

1. A low-cost, large-scale preparation method of defective molybdenum oxide quantum dots, characterized in that: The steps include: The hydrogen peroxide reagent is mixed with ethanol to form a mixed solvent, and then molybdenum disulfide (MoS2) powder is added in batches. After stirring evenly, it is placed in a high-speed shear emulsifier for treatment, and then centrifuged to obtain the supernatant to obtain a defective molybdenum oxide quantum dot solution.

2. A low-cost, large-scale preparation method of defective molybdenum oxide quantum dots according to claim 1, characterized in that: The hydrogen peroxide reagent is a 30% aqueous solution by mass, and the volume ratio of hydrogen peroxide to ethanol is between 1:3 and 1:

9.

3. A low-cost, large-scale preparation method of defective molybdenum oxide quantum dots according to claim 1, characterized in that: The addition amount of the molybdenum disulfide powder and the hydrogen peroxide reagent in the mixed solvent is maintained at 0.1 gram per milliliter.

4. The low-cost, large-scale preparation method of defective molybdenum oxide quantum dots according to claim 1, characterized in that: The shearing treatment time in the high-speed shear emulsifier is between 1 hour and 3 hours, and the centrifugal speed of the centrifugal treatment is 2500-4000r / min.

5. The low-cost, large-scale preparation method of defective molybdenum oxide quantum dots according to claim 1, characterized in that: The molybdenum oxide quantum dots have an average size of about 5 nanometers.

6. The electrochromic application of defective molybdenum oxide quantum dot solution is characterized by: The synthesized defective molybdenum oxide quantum dot solution is uniformly coated on the surface of the substrate in a certain manner, and after being naturally dried or low-temperature dried, an integrated electrochromic device is obtained.

7. The electrochromic application of the defective molybdenum oxide quantum dot solution according to claim 6, characterized in that: The processing of the substrate is: Patterned electrodes are processed on the flat substrate surface according to the content of the display information, and there is no conduction between the electrodes so that a power source can be connected to apply voltage.

8. The electrochromic application of the defective molybdenum oxide quantum dot solution according to claim 7, characterized in that: Laser etching technology is used to pattern the surface of tin-doped indium oxide (ITO) glass and fluorine-doped tin oxide (FTO) glass to divide them into multiple independent areas. Alternatively, the evaporation coating process is combined with a mask with a hollow pattern to plate gold electrodes on substrates such as PET plastic film and glass.

9. The electrochromic application of the defective molybdenum oxide quantum dot solution according to claim 6, characterized in that: The certain method refers to a liquid phase film forming method of drip coating or spray coating, and the temperature range of low-temperature drying is 25-80° C. to avoid crystallization of the obtained molybdenum oxide.

10. The electrochromic application of the defective molybdenum oxide quantum dot solution according to claim 6, characterized in that: The integrated electrochromic device can be reversibly switched between a colored state and a faded state, and its transmittance is dynamically and continuously adjustable.

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