PEDOT: PSS-based high-performance electrochromic conductive ink and preparation method thereof

Abstract

The invention is applicable to the field of technical improvement of printing materials, and provides high-performance electrochromic conductive ink based on PEDOT: PSS (poly (3, 4-ethylenedioxythiophene)-polystyrene sulfonate), which is characterized in that the electrochromic conductive ink is prepared from the following components in percentage by weight: 1.5 percent of poly (3, 4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT: PSS), 10 to 30 percent of NiO nanocrystalline and 0.1 to 1 percent of carbon quantum dots. By adopting the technical scheme, the ink has the characteristics of high response speed, high color change contrast ratio and good stability.

Description

Technical Field

[0001] The present invention relates to printing materials, and particularly to electrochromic inks and their manufacturing methods. Background Art

[0002] In the process of modern scientific and technological development, electrochromic materials have shown great application potential in many fields. For example, in the field of display technology, they can be used to manufacture electronic papers, flexible displays, etc., to achieve low-power consumption and high-contrast display effects; in the field of smart windows, they can automatically adjust the transparency of windows according to external light and temperature conditions to achieve energy conservation and a comfortable indoor environment; in the field of anti-counterfeiting labels, the unique color-changing characteristics of electrochromic materials can be used to make anti-counterfeiting labels that are difficult to forge.

[0003] Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), as a typical conductive polymer, has become one of the research hotspots in electrochromic materials due to its good electrical conductivity, optical transparency, film-forming property, and environmental stability. However, current electrochromic materials based on PEDOT:PSS have problems such as slow response speed, low color change contrast, and poor stability, and still face many challenges in practical applications. Especially when combining PEDOT:PSS with other materials with synergistic effects to prepare electrochromic conductive inks, there is currently no mature technical solution that can simultaneously solve the above multiple problems regarding their effective compounding, uniform dispersion, and precise performance regulation. Summary of the Invention

[0004] The present invention solves the technical problems of slow response speed, low color change contrast, and poor stability in the prior art by improving the ink manufacturing materials and processes, adding components beneficial for conductivity and diffusion to traditional inks, and controlling the manufacturing processes.

[0005] This high-performance electrochromic conductive ink based on PEDOT:PSS prepared by the present invention to solve the above technical problems contains poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a solid content of 1.5 wt%, 10 - 30 wt% NiO nanocrystals, and 0.1 - 1 wt% carbon quantum dots; the NiO nanocrystals have a particle size of 10 - 15 nm, and the carbon quantum dots have a particle size of 5 nm.

[0006] The manufacturing method of this high-performance electrochromic conductive ink: This method includes the following steps: A. Weigh an aqueous PEDOT:PSS solution with a solid content of 1.5 wt% as the base material; B. Weigh NiO nanocrystals with a particle size of 10 - 15 nm at 10 - 30 wt% of the mass of the PEDOT:PSS aqueous solution, and slowly add them to the PEDOT:PSS aqueous solution. Under the condition of an ultrasonic frequency of 25 - 40 kHz, perform ultrasonic treatment for 20 - 40 minutes; C. Weigh carbon quantum dots (CDs, with an average particle size of 5 nm) at 0.1 - 1 wt% of the total mass, add them to the mixed solution in step B, and continue ultrasonic treatment for 20 - 40 minutes under the condition of an ultrasonic frequency of 25 - 40 kHz to obtain a uniformly dispersed mixed matrix solution incorporating a third component.

[0007] D. Dilute the PEDOT:PSS aqueous solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) at 10% of the above volume to make a DMSO - PEDOT:PSS mixed solution; E. Prepare mixed solutions with different concentrations according to requirements; F. At room temperature, place the mixed solution prepared in step E in a rotary evaporator, perform rotary evaporation at a speed of 100 r / min, and gradually heat up to 60 °C to form a core - shell structure dispersion in which NiO nanocrystals are coated with PEDOT:PSS. The thickness of the PEDOT:PSS coating on the NiO nanocrystals is maintained between 2 and 3 nm.

[0008] Repeat steps E and F to make dispersions with different concentrations; G. Take at least two dispersions with different concentrations, inject them into different inlets of a microfluidic chip respectively, and mix the two dispersions with different concentrations into a stratified mixed solution with different gradient doping characteristics by controlling the flow rates of each inlet. For example, use concentrations of 0.5 mg / mL, 1 mg / mL, and 2 mg / mL respectively, inject them into different inlets of the microfluidic chip, and by precisely controlling the flow rates of each inlet, such as the flow rate of the 0.5 mg / mL dispersion is 0.1 mL / min, the flow rate of the 1 mg / mL dispersion is 0.2 mL / min, and the flow rate of the 2 mg / mL dispersion is 0.3 mL / min, make them meet and mix in the flow channels inside the chip, and finally collect the mixed dispersion with gradient doping characteristics from the outlet of the microfluidic chip.

[0009] H. According to the requirements of ink use, inject a thickening agent into the stratified mixed solution made in step G to meet the requirements of ink use. The thickening agent described in step H is hydroxyethyl cellulose.

[0010] I. Inject a film - forming auxiliary agent into the ink formed in step H, stir at a speed of 100 - 200 r / min for 30 - 60 minutes, and finally obtain a conductive ink with gradient doping characteristics based on PEDOT:PSS. The film - forming auxiliary agent is propylene glycol methyl ether acetate.

[0011] By adopting the above technical solution, the ink of the present invention has the characteristics of fast response speed, high color change contrast and good stability. Specific embodiments

[0012] Specific embodiments of the present invention include the following solutions: This high-performance electrochromic conductive ink based on PEDOT:PSS contains poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a solid content of 1.5 wt%, 10-30 wt% NiO nanocrystals, and 0.1-1 wt% carbon quantum dots. The NiO nanocrystals have a particle size of 10-15 nm, and the carbon quantum dots have a particle size of 5 nm.

[0013] The manufacturing method of the above high-performance electrochromic conductive ink based on PEDOT:PSS: This method includes the following steps: A. Weigh an aqueous solution of PEDOT:PSS with a solid content of 1.5 wt% as the base material; B. Weigh NiO nanocrystals with a particle size of 10-15 nm according to 10-30 wt% of the mass of the PEDOT:PSS aqueous solution, slowly add them to the PEDOT:PSS aqueous solution, and under the condition of an ultrasonic frequency of 25-40 kHz, perform ultrasonic treatment for 20-40 minutes to preliminarily and uniformly disperse the NiO nanocrystals in the PEDOT:PSS solution; C. Weigh carbon quantum dots according to 0.1-1 wt% of the total mass, add them to the mixed solution in step B, and continue ultrasonic treatment for 20-40 minutes under the condition of an ultrasonic frequency of 25-40 kHz to obtain a uniformly dispersed mixed matrix solution with the introduction of a third component.

[0014] By introducing carbon quantum dots (CDs), a synergistic conductive network is formed with NiO nanocrystals and PEDOT:PSS, significantly improving the conductivity of the conductive ink. At the same time, the p-type semiconductor characteristics of NiO nanocrystals and the p-doping characteristics of PEDOT:PSS cooperate with each other to further optimize the electron transport path and accelerate the ink color change response speed.

[0015] The improved embodiment of the present invention includes the following steps after step C: D. Dilute the PEDOT:PSS aqueous solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) according to 10% of the above volume to make a DMSO-PEDOT:PSS mixed solution; E. Take an appropriate amount of the mixed matrix solution prepared in step C according to the concentration requirement, and add it to the DMSO-PEDOT:PSS mixed solution prepared in step D to make a mixed solution meeting the concentration requirement; keep the mass ratio of NiO nanocrystals in the mixed solution reaching 20%. F. At room temperature, place the mixed solution prepared in step E in a rotary evaporator, rotate it at a speed of 100 r / min, and gradually heat it up to 60 °C. According to the requirements of different concentrations, control the evaporation time and temperature to form a core-shell structure dispersion of PEDOT:PSS-coated NiO nanocrystals with different concentrations. The thickness of the PEDOT:PSS coating on the NiO nanocrystals is maintained between 2 and 3 nm. The core-shell structure formed by PEDOT:PSS coating NiO nanocrystals effectively inhibits the aggregation of NiO nanocrystals and enhances the stability of the material in the ink system; the flexibility of PEDOT:PSS and the brittleness of NiO are complementary, which can improve the film-forming property and mechanical stability of the ink; the addition of carbon quantum dots also helps to stabilize the whole system and reduce the influence of environmental factors on the performance. The complementary color-changing mechanism improves the color-changing effect: the color-changing ranges of PEDOT:PSS (dark blue in the reduced state, transparent in the oxidized state) and NiO (dark brown in the oxidized state, transparent in the reduced state) are complementary, which can broaden the spectral response (such as realizing two-color / multicolor switching). Compared with a single material system, the contrast (ΔT>50 %) or color richness can be improved.

[0016] Repeat steps E and F to make dispersions with different concentrations.

[0017] G. Take at least two dispersions with different concentrations, inject them into different inlets of the microfluidic chip respectively, and mix the two dispersions with different concentrations into a stratified mixed solution with different gradient doping characteristics by controlling the flow rates of each inlet. The dispersions with different concentrations flow and diffuse with each other in the flow channel, so as to realize the gradient distribution of NiO nanocrystals in PEDOT:PSS. The gradient doping characteristics in the liquid ink enable the conductive ink to have different conductive properties at different positions, which can be customized according to specific application requirements, meeting the strict requirements for high-conductivity and diverse conductive property materials.

[0018] H. According to the ink usage requirements, inject a thickener into the stratified mixed solution prepared in step G to adjust the viscosity of the ink to meet the printing process requirements. The thickener is preferably hydroxyethyl cellulose.

[0019] I. Inject a film-forming aid into the ink formed in step H, stir it at a speed of 100 - 200 r / min for 30 - 60 minutes, and finally obtain a conductive ink with gradient doping characteristics based on PEDOT:PSS. The film-forming aid is propylene glycol methyl ether acetate.

[0020] Example 1 Weigh an aqueous PEDOT:PSS solution with a solid content of 1.5 wt% as the base material, and weigh mixed NiO nanocrystals with a particle size of 10 - 15 nm at 10 wt% of the mass of the PEDOT:PSS solution, and slowly add it to the aqueous PEDOT:PSS solution. Under the condition of an ultrasonic frequency of 25 kHz, ultrasonically treat for 20 minutes to preliminarily and uniformly disperse the NiO nanocrystals in the PEDOT:PSS solution. Then, weigh carbon quantum dots (CDs, with an average particle size of 5 nm) at 0.1 wt% of the total mass, add them to the above mixed solution, and continue ultrasonically treating for 20 minutes under the condition of an ultrasonic frequency of 25 kHz to obtain a uniformly dispersed mixed matrix solution with a third component introduced.

[0021] Dilute the aqueous PEDOT:PSS solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) in a volume ratio of 1:10 to improve the film-forming performance and conductivity of PEDOT:PSS. Take an appropriate part from the mixed matrix solution and slowly add it to the above diluted PEDOT:PSS solution added with DMSO so that the mass ratio of NiO nanocrystals in the mixed system reaches 20%. At room temperature, place the mixed solution in a rotary evaporator and perform rotary evaporation at a rotation speed of 100 r / min, and gradually heat up to 60 °C. By precisely controlling conditions such as evaporation time and temperature, uniformly coat PEDOT on the surface of the NiO nanocrystals to form a shell layer with a thickness of 2 nm, thereby obtaining a dispersion of PEDOT:PSS-coated NiO nanocrystals with a core-shell structure.

[0022] Adopt microfluidic technology to mix the dispersion through a microfluidic chip, so that dispersions with different concentrations flow and diffuse with each other in the flow channel, thereby realizing the gradient distribution of NiO nanocrystals in PEDOT:PSS.

[0023] Prepare dispersions of PEDOT:PSS-coated NiO nanocrystals with different concentrations, which are 0.5 mg / mL, 1 mg / mL, and 2 mg / mL respectively. Inject them into different inlets of the microfluidic chip, and by precisely controlling the flow rates of each inlet, such as the flow rate of the 0.5 mg / mL dispersion is 0.1 mL / min, the flow rate of the 1 mg / mL dispersion is 0.2 mL / min, and the flow rate of the 2 mg / mL dispersion is 0.3 mL / min, make them meet and mix in the flow channel inside the chip, and finally collect the mixed dispersion with gradient doping characteristics from the outlet of the microfluidic chip.

[0024] Add an appropriate amount of thickener, such as hydroxyethyl cellulose, with an addition amount of 0.5 wt% of the mass of the dispersion, to the dispersion with gradient doping characteristics to adjust the viscosity of the ink to meet the requirements of the printing process. Add a film-forming auxiliary agent with a mass fraction of 1 wt%, such as propylene glycol methyl ether acetate, to further improve the film-forming performance of the ink. Under the condition of low-speed stirring, mix evenly, control the stirring speed at 100 r / min, and the stirring time is 30 minutes to finally obtain a conductive ink based on PEDOT:PSS with gradient doping characteristics.

[0025] Example 2 Weigh an aqueous PEDOT:PSS solution with a solid content of 1.5 wt% as the base material, and weigh mixed NiO nanocrystals with a particle size of 10 - 15 nm according to 10 wt% of the mass of the PEDOT:PSS solution, and slowly add it to the aqueous PEDOT:PSS solution. Under the condition of an ultrasonic frequency of 30 kHz, perform ultrasonic treatment for 30 minutes to preliminarily disperse the NiO nanocrystals evenly in the PEDOT:PSS solution. Then, weigh carbon quantum dots (CDs, with an average particle size of 5 nm) according to 0.7 wt% of the total mass, add them to the above mixed solution, and continue ultrasonic treatment for 30 minutes under the condition of an ultrasonic frequency of 30 kHz to obtain a uniformly dispersed mixed matrix solution with a third component introduced.

[0026] Dilute the aqueous PEDOT:PSS solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) according to a volume ratio of 1:10 to improve the film-forming performance and conductivity of PEDOT:PSS. Take an appropriate part from the mixed matrix solution and slowly add it to the above diluted PEDOT:PSS solution added with DMSO so that the mass ratio of NiO nanocrystals in the mixed system reaches 20%. At room temperature, place the mixed solution in a rotary evaporator and perform rotary evaporation at a speed of 100 r / min, and gradually heat up to 60 °C. By precisely controlling conditions such as evaporation time and temperature, make PEDOT uniformly coat on the surface of NiO nanocrystals to form a shell layer with a thickness of 2.5 nm, thereby obtaining a dispersion of NiO nanocrystals coated with PEDOT:PSS with a core-shell structure.

[0027] Adopt microfluidic technology to mix the dispersion through a microfluidic chip, so that dispersions with different concentrations flow and diffuse with each other in the flow channel, thereby realizing the gradient distribution of NiO nanocrystals in PEDOT:PSS.

[0028] Prepare PEDOT:PSS-coated NiO nanocrystal dispersions with different concentrations, namely 0.5 mg / mL, 1 mg / mL, and 2 mg / mL. Inject them into different inlets of the microfluidic chip respectively. By precisely controlling the flow rates of each inlet, such as the flow rate of the 0.5 mg / mL dispersion being 0.1 mL / min, the flow rate of the 1 mg / mL dispersion being 0.2 mL / min, and the flow rate of the 2 mg / mL dispersion being 0.3 mL / min, make them meet and mix in the flow channels inside the chip, and finally collect the mixed dispersion with gradient doping characteristics from the outlet of the microfluidic chip.

[0029] Add an appropriate amount of thickener, such as hydroxyethyl cellulose, with an addition amount of 1.0 wt% of the dispersion mass, to the dispersion with gradient doping characteristics to adjust the viscosity of the ink to meet the requirements of the printing process. Add a film-forming auxiliary with a mass fraction of 2 wt%, such as propylene glycol methyl ether acetate, to further improve the film-forming performance of the ink. Under the condition of low-speed stirring, mix evenly, control the stirring speed at 150 r / min, and the stirring time is 45 minutes. Finally, obtain a conductive ink based on PEDOT:PSS with gradient doping characteristics.

[0030] Example 3 Weigh an aqueous PEDOT:PSS solution with a solid content of 1.5 wt% as the base material, and weigh mixed NiO nanocrystals with a particle size of 10 - 15 nm at 10 wt% of the mass of the PEDOT:PSS solution, and slowly add them to the aqueous PEDOT:PSS solution. Under the condition of an ultrasonic frequency of 40 kHz, perform ultrasonic treatment for 40 minutes to preliminarily disperse the NiO nanocrystals evenly in the PEDOT:PSS solution. Then, weigh carbon quantum dots (CDs, with an average particle size of 5 nm) at 1 wt% of the total mass, add them to the above mixed solution, and continue ultrasonic treatment for 40 minutes under the condition of an ultrasonic frequency of 40 kHz to obtain a uniformly dispersed mixed matrix solution with a third component introduced.

[0031] Dilute the aqueous PEDOT:PSS solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) in a volume ratio of 1:10 to improve the film-forming performance and conductivity of PEDOT:PSS. Take an appropriate part from the mixed matrix solution and slowly add it to the above diluted PEDOT:PSS solution with DMSO added, so that the mass ratio of NiO nanocrystals in the mixed system reaches 20%. At room temperature, place the mixed solution in a rotary evaporator and rotate it at a speed of 100 r / min, and gradually heat up to 60 °C. By precisely controlling conditions such as the evaporation time and temperature, make PEDOT uniformly coat on the surface of NiO nanocrystals to form a shell layer with a thickness of 3 nm, thereby obtaining a PEDOT:PSS-coated NiO nanocrystal dispersion with a core-shell structure.

[0032] Using microfluidic technology, the dispersion liquid is mixed through a microfluidic chip, enabling the dispersion liquids with different concentrations to flow and diffuse with each other in the flow channel, thereby achieving a gradient distribution of NiO nanocrystals in PEDOT:PSS.

[0033] Prepare PEDOT:PSS-coated NiO nanocrystal dispersion liquids with different concentrations, which are 0.5 mg / mL, 1 mg / mL, and 2 mg / mL respectively. Inject them into different inlets of the microfluidic chip. By precisely controlling the flow rates of each inlet, such as the flow rate of the 0.5 mg / mL dispersion liquid is 0.1 mL / min, the flow rate of the 1 mg / mL dispersion liquid is 0.2 mL / min, and the flow rate of the 2 mg / mL dispersion liquid is 0.3 mL / min, make them meet and mix in the flow channel inside the chip, and finally collect the mixed dispersion liquid with gradient doping characteristics from the outlet of the microfluidic chip.

[0034] Add an appropriate amount of thickener, such as hydroxyethyl cellulose, to the dispersion liquid with gradient doping characteristics. Its addition amount is 1.5 wt% of the mass of the dispersion liquid to adjust the viscosity of the ink to meet the requirements of the printing process. Add a film-forming auxiliary agent with a mass fraction of 3 wt%, such as propylene glycol methyl ether acetate, to further improve the film-forming performance of the ink. Under the condition of low-speed stirring, mix evenly. Control the stirring speed at 200 r / min and the stirring time at 60 minutes. Finally, obtain a conductive ink based on PEDOT:PSS with gradient doping characteristics.

[0035] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A high-performance electrochromic conductive ink based on PEDOT:PSS, characterized in that, The electrochromic conductive ink contains poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) with a solid content of 1.5 wt%, 10-30 wt% NiO nanocrystals, and 0.1-1 wt% carbon quantum dots.

2. The high-performance electrochromic conductive ink based on PEDOT:PSS according to claim 1, wherein: The NiO nanocrystals have a particle size of 10-15 nm, and the carbon quantum dots have a particle size of 5 nm.

3. A method for preparing a high-performance electrochromic conductive ink based on PEDOT:PSS as claimed in claim 1 or 2: The method includes the following steps: A. Weigh an aqueous PEDOT:PSS solution with a solid content of 1.5 wt% as the base material; B. Weigh NiO nanocrystals with a particle size of 10-15 nm according to the mass of the aqueous PEDOT:PSS solution at 10-30 wt%, slowly add it to the aqueous PEDOT:PSS solution, and under the condition of an ultrasonic frequency of 25-40 kHz, perform ultrasonic treatment for 20-40 minutes; C. Weigh carbon quantum dots according to 0.1-1 wt% of the total mass, add them to the mixed solution in step B, and continue ultrasonic treatment for 20-40 minutes under the condition of an ultrasonic frequency of 25-40 kHz to obtain a uniformly dispersed mixed matrix solution with a third component introduced.

4. The manufacturing method according to claim 3, wherein: After step C, the method further includes the following steps: D. Dilute the aqueous PEDOT:PSS solution with deionized water to a solid content of 0.5 wt%, and add dimethyl sulfoxide (DMSO) according to 10% of the above volume to make a DMSO-PEDOT:PSS mixed solution; E. Take an appropriate amount of the mixed matrix solution prepared in step C according to the concentration requirement, and add it to the DMSO-PEDOT:PSS mixed solution prepared in step D to make a mixed solution that meets the concentration requirement; F. At room temperature, place the mixed solution prepared in step E in a rotary evaporator, perform rotary evaporation at a rotation speed of 100 r / min, and gradually heat up to 60 °C to form a core-shell structure dispersion of PEDOT:PSS-coated NiO nanocrystals.

5. The manufacturing method according to claim 4, characterized in that: The thickness of the PEDOT:PSS coating on the NiO nanocrystals in step F is maintained between 2 and 3 nm.

6. The manufacturing method according to claim 4 or 5, characterized in that: Repeat steps E and F to make dispersions with different concentrations.

7. According to the manufacturing method described in claim 6, the characteristics are as follows: G. Take at least two dispersions with different concentrations, inject them into different inlets of a microfluidic chip respectively, and mix the two dispersions with different concentrations into a layered mixed solution with different gradient doping characteristics by controlling the flow rates of each inlet. H. According to the ink usage requirements, inject a thickener into the layered mixed solution prepared in step G to meet the ink usage requirements.

8. The manufacturing method according to claim 8, characterized in that: The thickener described in step H is hydroxyethyl cellulose, and the addition amount of the thickener is 0.5-1.5 wt% of the layered mixed solution.

9. The manufacturing method according to claim 7, characterized in that: After step H, the following steps are further included: I. Inject a film-forming aid into the ink formed in step H, stir it at a speed of 100-200 r / min for 30-60 minutes, and finally obtain a conductive ink based on PEDOT:PSS with gradient doping characteristics.

10. The manufacturing method according to claim 7, characterized in that: The film-forming aid described in Step I is propylene glycol methyl ether acetate, and the addition amount of the film-forming aid is 1-3 wt% of the layered mixture.