CN115785499A

CN115785499A - High-conductivity stretchable PEDOT (Polytetrafluoroethylene-PSS) film as well as preparation method and application thereof

Info

Publication number: CN115785499A
Application number: CN202211518818.3A
Authority: CN
Inventors: 韩艳春; 陈海琦; 于新红
Original assignee: Changchun Institute of Applied Chemistry of CAS
Current assignee: Changchun Institute of Applied Chemistry of CAS
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2023-03-14

Abstract

The invention relates to a high-conductivity stretchable PEDOT (polyethylene glycol terephthalate) PSS (Poly ethylene terephthalate) film as well as a preparation method and application thereof, belonging to the field of conductive high-molecular functional materials. The PEDOT PSS film is formed by blending conductive polymers PEDOT PSS, water-soluble polymer polyvinyl alcohol and polyhydroxy compound sorbitol or glycerol serving as a dopant. The preparation method of the PEDOT PSS film comprises the steps of adding water-soluble polymer compound polyvinyl alcohol, sorbitol or glycerol into a PEDOT PSS solution, heating, stirring and uniformly mixing to obtain a stretchable PEDOT PSS solution with high conductivity, spin-coating the solution on a substrate with a processed surface, annealing and drying to obtain the flexible conductive transparent film. The PEDOT PSS film prepared by the invention has the advantages of high conductivity, high transparency, good mechanical property and the like, and can be applied to flexible photoelectric devices as transparent conductive electrodes.

Description

High-conductivity stretchable PEDOT (Polytetrafluoroethylene-PSS) film as well as preparation method and application thereof

Technical Field

The invention belongs to the field of conductive high-molecular functional materials, and particularly relates to a high-conductivity stretchable PEDOT (polyethylene glycol terephthalate) (PSS) film as well as a preparation method and application thereof.

Background

As basic elements in flexible electronic devices, flexible transparent conductive electrodes (FTEs) are widely applied to flexible electronic products such as high-efficiency scalable organic photovoltaic cells (OPVs), organic Light Emitting Diodes (OLEDs), flexible touch panels, and the like. Transparent electrodes commonly used at present are conventional metal oxide Indium Tin Oxide (ITO) and fluorine-doped tin oxide of low resistance and high transparency, having a high light transmittance (T%) of 80-90% and 10-20 Ω · sq ^-1 Low sheet resistance (R) _sh ) ITO electrodes have been widely used in rigid opto-electronic devices fabricated on glass. However, due to the inherent disadvantages of poor mechanical stability of the ITO electrode, high cost of the high temperature vacuum deposition method, etc., when the ITO electrode is deposited on the plastic substrate, the electrical conductivity is greatly reduced, which becomes worse under mechanical stress, and is not suitable for a flexible transparent electrode. Therefore, a transparent electrode with low cost, good conductivity and reasonable mechanical flexibility is urgently needed to be found to replace the ITO.

One of the main requirements of the deformable stretchable electrode is to maintain basic functionality in various modes of mechanical deformation. In most practical applications, flexibility and stretchability are as important as electrical properties. These devices must be able to bend and deform freely without damage. Several popular materials such as carbon nanotubes, metal nanowires, graphene, and conductive polymers are widely studied as possible transparent electrode substitutes. While these materials show great potential as large-scale electrodes in place of ITO, each of the conductive materials suffers from one or more disadvantages, including low flexibility, poor adhesion, moderate conductivity, general transparency, high surface roughness, poor wettability, and stability issues, which do hinder the development of conductive materials.

Among them, the conductive polymer poly (3, 4-ethylenedioxythiophene) (poly (styrenesulfonate) (PEDOT: PSS)) has high light transmittance in the visible light region, excellent flexibility, good solution processability and good conductivity, and becomes a new generation of transparent conductive electrode. PSS also has flexibility in adjusting molecular structure and electrical and mechanical properties, providing additional advantages for large-scale production of flexible electronics. Therefore, further research on a PEDOT/PSS structure regulation and control means is needed, a structure which is more favorable for performance is obtained, and a PEDOT/PSS film with more excellent performance is developed, so that the method has important guiding significance for further application of a PEDOT/PSS stretchable electrode.

Disclosure of Invention

In view of the above, the present invention aims to provide a highly conductive and stretchable PEDOT: PSS film with good stability, and a preparation method and applications thereof. The invention successfully develops a PEDOT/PSS film doped with polyvinyl alcohol and sorbitol or glycerol, which has good conductivity and transparency and good mechanical properties.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

the invention provides a high-conductivity stretchable PEDOT PSS film, which is formed by blending a conductive polymer, a water-soluble polymer serving as a dopant and a polyhydroxy compound;

PSS, polyvinyl alcohol as the water-soluble polymer, and sorbitol or glycerol as the polyhydroxy compound.

Preferably, in the high-conductivity stretchable PEDOT/PSS film, the content of the water-soluble polymer polyvinyl alcohol is 5-15 wt%, and the content of the adulterant sorbitol or glycerol is 2-10 wt%.

It is further preferred that the highly conductive stretchable PEDOT: PSS film contains 5wt% or 10wt% of water-soluble polymer polyvinyl alcohol, 4wt% of dopant sorbitol or 8wt% of dopant glycerin.

The invention also provides a preparation method of the high-conductivity stretchable PEDOT: PSS film, which comprises the following steps:

(1) Dissolving water-soluble polymer polyvinyl alcohol in deionized water, and heating and stirring to obtain a polyvinyl alcohol solution;

(2) Mixing the polyvinyl alcohol solution and the polyhydroxy compound with PEDOT (Poly ethylene glycol ether sulfonate) PSS solution, heating, stirring and uniformly mixing to obtain stretchable PEDOT (Poly ethylene sulfonate) PSS solution with high conductivity;

(3) And (3) spin-coating the PEDOT/PSS solution obtained in the step (2) on the substrate with the processed surface, and annealing and drying to obtain the high-conductivity stretchable PEDOT/PSS film.

Preferably, the polymerization degree of the water-soluble polymer polyvinyl alcohol in the step (1) is 1500-2400, the alcoholysis degree is 99%, and the concentration of the polyvinyl alcohol aqueous solution is 5wt%; the PEDOT prepared in the step (2) is that the PSS solution contains 5 to 15 weight percent of polyvinyl alcohol and 2 to 10 weight percent of sorbitol or glycerol.

It is further preferred that the solution of PEDOT: PSS formulated in step (2) contains 5wt% or 10wt% polyvinyl alcohol, and 4wt% sorbitol or 8wt% glycerol.

Preferably, the heating and stirring in the step (1) is performed at a rotation speed of 500rpm/min to 700rpm/min at 90 ℃.

Preferably, the heating and stirring in the step (2) are carried out at a rotation speed of 1000rpm/min to 1200rpm/min at 90 ℃.

Preferably, the substrate in step (3) is a flexible substrate or a rigid substrate, the flexible substrate is hydrogenated styrene-butadiene block copolymer (SEBS), and the rigid substrate is a glass sheet; the surface treatment of the substrate is that the substrate is sequentially cleaned by deionized water, acetone and isopropanol under ultrasonic for 20min, and then an ultraviolet ozone cleaner is used for carrying out surface treatment on the substrate, wherein the treatment time is 25min; the spin coating is specifically 1000 rpm/min-3000 rpm/min for 60s; the annealing and drying temperature is 120-180 ℃, and the time is 15-30 min; the thickness of the obtained high-conductivity stretchable PEDOT, namely PSS film is 120 nm-200 nm.

The invention also provides application of the high-conductivity stretchable PEDOT: PSS film as a transparent conductive electrode in a flexible photoelectric device.

The invention principle of the invention is as follows: the polyvinyl alcohol is a soft polymer, and is introduced into a PEDOT/PSS system, so that the tensile property of the film can be effectively improved, but the electric conductivity of the film is extremely low due to the insulating property of the film. Sorbitol or glycerol, on the other hand, is a polar solvent containing hydroxyl groups and is capable of large interactions with the PEDOT and PSS phases, resulting in rearrangement and formation of a dense morphology of the PEDOT and PSS segments. The use of sorbitol or glycerol as an additive allows phase separation between the PEDOT and PSS regions, leading to aggregation of the PEDOT region, the formation of conductive pathways, and the benzene to quinone transformation of the PEDOT backbone. The addition of the polyol results in a better conductive path and thus results in an improved conductivity of PVA/PEDOT: PSS films doped with polyol. Meanwhile, the polyvinyl alcohol contains hydroxyl, and the polyhydroxy compound sorbitol or glycerol can also be used as a plasticizer of the polyvinyl alcohol, so that the mechanical tensile property of the film can be further improved. And the glycerol has higher dielectric constant than sorbitol, so that the stronger shielding effect than sorbitol can weaken the coulomb force between PEDOT molecules with positive charges and PSS molecules with negative charges, improve the transition rate of charge transmission and further improve the conductivity of the film.

The beneficial effects of the invention are:

when the high-conductivity stretchable PEDOT: PSS film provided by the invention uses polyvinyl alcohol and sorbitol or glycerol as a doping agent of the PEDOT: PSS, the ratio of the PEDOT: the PSS flexible conductive transparent film has high elongation at break and keeps good conductivity. Wherein the elongation at break can reach 193.0% at most, and the conductivity can reach 660.5S/cm at most. The conductive film has the advantages of high conductivity, good transparency, good mechanical property and the like, and can be applied to flexible photoelectric devices as transparent conductive electrodes.

Drawings

FIG. 1 is a real picture of the stretched PEDOT PSS flexible conductive transparent film of the present invention.

FIG. 2 is a graph showing the stress-strain curves of the films of comparative example and examples 1 to 4 according to the present invention.

FIG. 3 is an AFM phase diagram representation of comparative and example 1PEDOT PSS films of the present invention.

FIG. 4 is an AFM height profile characterization of comparative and example 1PEDOT PSS films of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. This detailed description is not to be taken in a limiting sense, but is to be understood as a more detailed description of certain aspects, features and embodiments of the invention.

Example 1

(1) The polyvinyl alcohol solid was dissolved in deionized water at a ratio of 5wt% and stirred at 600rpm/min at 90 ℃ for about 4 hours until a uniform and transparent PVA solution was obtained. The solubility of the polyvinyl alcohol is 1700, and the alcoholysis degree is 99%.

(2) And (2) mixing approximately 5g of PEDOT (PSS) solution with the PVA solution obtained in the step (1), wherein the content of the PVA solution is 10wt%, and stirring at the rotating speed of 1200rpm/min at 90 ℃ until a uniformly mixed solution is obtained.

(3) Sorbitol with the purity of 98% is selected as a doping agent and is mixed with the mixed solution in the step (2) to enable the doping amount of the sorbitol to be 4wt%, and the mixed solution is stirred at the rotating speed of 1200rpm/min at the temperature of 90 ℃ until the uniformly mixed solution is obtained.

(4) A1.5 cm multiplied by 1.5cm glass sheet is selected as a substrate, the substrate is soaked in a mixture (7.

(5) The mixed solution in step (3) was filtered using a 0.45 μm filter head to remove large particles in the solution. And (3) taking 100 mu L of mixed liquid drop by using a liquid transfer gun, spin-coating the mixed liquid drop on the processed glass sheet substrate for 60s at the speed of 2000rpm/min, and annealing and drying the mixed liquid drop at the temperature of 160 ℃ for 20min to obtain the PEDOT: PSS flexible conductive transparent film, wherein the thickness of the film is about 155nm.

(6) The prepared PEDOT/PSS flexible conductive transparent film is subjected to test verification of conductivity performance, and the result is shown in Table 1.

(7) And (3) dripping 4mL of the mixed liquid obtained in the step (3) on a polytetrafluoroethylene die by using a liquid transfer gun, and drying at 25 ℃ for more than 10h to obtain the self-supporting substrate-free PEDOT: PSS film.

(8) The mechanical property test of the prepared PEDOT/PSS film is verified, and the result is shown in figure 2.

Example 2

(2) And (3) mixing approximately 5g of PEDOT (PSS) solution with the PVA solution obtained in the step (1), wherein the content of the PVA solution is 15wt%, and stirring at the rotating speed of 1200rpm/min at 90 ℃ until a uniformly mixed solution is obtained.

(3) Selecting 98% sorbitol as dopant, mixing with the mixed solution in step (2) to make sorbitol doping amount 4wt%, stirring at 90 deg.C at 1200rpm/min until uniform mixed solution is obtained.

(5) The mixed solution in step (3) was filtered using a 0.45 μm filter head to remove large particles in the solution. And (3) taking 100 mu L of mixed liquid drop by using a liquid transfer gun, spin-coating the mixed liquid drop on the processed glass sheet substrate for 60s at the speed of 2000rpm/min, and annealing and drying the mixed liquid drop at the temperature of 160 ℃ for 20min to obtain the PEDOT: PSS flexible conductive transparent film, wherein the thickness of the film is about 200nm.

(8) The obtained PEDOT PSS film is verified by mechanical property tests, and the result is shown in figure 2.

Example 3

(2) And (2) mixing PEDOT, namely PSS solution, about 5g and PVA solution in the step (1), wherein the content of the PVA solution is 10wt%, and stirring at the rotation speed of 1200rpm/min at 90 ℃ until uniformly mixed solution is obtained.

(3) And (3) selecting glycerol as a doping agent, mixing the glycerol with the mixed solution in the step (2) to ensure that the doping amount of the glycerol is 4wt%, and stirring at the rotation speed of 1200rpm/min at 90 ℃ until a uniformly mixed solution is obtained.

(5) The mixed solution in step (3) was filtered using a 0.45 μm filter head to remove large particles in the solution. And (3) taking 100 mu L of mixed liquid drop by using a liquid transfer gun, spin-coating the mixed liquid drop on the processed glass sheet substrate for 60s at the speed of 2000rpm/min, and annealing and drying the mixed liquid drop at the temperature of 160 ℃ for 20min to obtain the PEDOT: PSS flexible conductive transparent film, wherein the thickness of the film is about 135nm.

(6) The prepared PEDOT/PSS flexible conductive transparent film is subjected to test verification of conductivity performance, and the results are shown in Table 1.

Example 4

(2) And (2) mixing PEDOT, namely PSS solution, about 5g and the PVA solution obtained in the step (1), wherein the content of the PVA solution is 5wt%, and stirring at the rotation speed of 1200rpm/min at 90 ℃ until uniformly mixed solution is obtained.

(3) And (3) selecting glycerol as a doping agent, mixing the glycerol with the mixed solution in the step (2) to ensure that the doping amount of the glycerol is 8wt%, and stirring at the rotation speed of 1200rpm/min at 90 ℃ until a uniformly mixed solution is obtained.

(5) The mixed solution in step (3) was filtered using a 0.45 μm filter head to remove large particles in the solution. And (3) taking 100 mu L of mixed liquid drop by using a liquid transfer gun, spin-coating the mixed liquid drop on the processed glass sheet substrate for 60s at the speed of 2000rpm/min, and annealing and drying the mixed liquid drop at the temperature of 160 ℃ for 20min to obtain the PEDOT: PSS flexible conductive transparent film, wherein the thickness of the film is about 120nm.

(7) And (4) dripping 4mL of the mixed liquid obtained in the step (3) on a polytetrafluoroethylene mold by using a liquid transfer gun, and drying at 25 ℃ for more than 10h to obtain the self-supporting substrate-free PEDOT: PSS film.

The conditions of solution heating and stirring, spin coating, annealing, etc. described in the above embodiments can be any values within the above-defined ranges, and PEDOT: PSS films with high conductivity, high transparency and good mechanical properties can be obtained, which is not exemplified here.

Comparative example

(1) Sorbitol with the purity of 98 percent is selected as a doping agent to be mixed with PEDOT, namely PSS solution, about 5g, the doping amount of the sorbitol is 4 weight percent, and the mixture is stirred at the rotating speed of 1200rpm/min at the temperature of 90 ℃ until the uniform mixed solution is obtained.

(2) A1.5 cm multiplied by 1.5cm glass sheet is selected as a substrate, the substrate is soaked in a mixture (7.

(3) The mixed solution in step (1) was filtered using a 0.45 μm filter head to remove large particles in the solution. And (3) dripping 100 mu L of mixed liquid on the processed glass sheet substrate by using a liquid transfer gun, spin-coating for 60s at the speed of 2000rpm/min, and annealing and drying at the temperature of 160 ℃ for 20min to obtain the PEDOT: PSS flexible conductive transparent film with the film thickness of about 105nm.

(4) The prepared PEDOT/PSS flexible conductive transparent film is subjected to test verification of conductivity performance, and the result is shown in Table 1.

(5) And (3) dripping 4mL of the mixed liquid obtained in the step (1) on a polytetrafluoroethylene die by using a liquid transfer gun, and drying at 25 ℃ for more than 10h to obtain the self-supporting substrate-free PEDOT: PSS film.

(6) Comparative example and PEDOT prepared in example 1: the PSS flexible conductive transparent film was subjected to AFM characterization, and the results are shown in FIGS. 3 and 4.

TABLE 1 Electrical and mechanical Properties of stretchable conductive films

	Elongation at Break (%)	Conductivity (S/cm)
			Example 1	118.7	329.7
Example 2	160.1	281.9
			Example 3	148.8	514.0
Example 4	193.0	660.5
			Comparative example	41.8	720.6

The appropriate PVA content and polyol content can be selected to obtain a highly conductive stretchable film, when a PEDOT: PSS film is prepared by selecting polyvinyl alcohol with the content of 10wt% or 5wt% and sorbitol with the content of 4wt% or glycerol with the content of 8wt%, the obtained conductivity can reach about 660.5S/cm at most, and the elongation at break of the film is 193.0%, and the performance of the film can be far higher than that of a film prepared by the common PEDOT: PSS.

FIG. 1 shows that the tensile properties of the film are greatly improved by the combined action of the polyvinyl alcohol and the polyhydroxy additive.

As can be seen from the comparison example, the examples 1 and 2 in fig. 2, when sorbitol is used as an additive, the tensile property of the film can be greatly improved and the elongation at break of the film can be greatly improved by introducing the soft polymer polyvinyl alcohol into the system; it can be seen from examples 1 and 3 that when polyvinyl alcohol, a soft polymer, is used as an additive, glycerol is selected as a polyhydroxy additive, and the tensile properties of the film can be improved to a greater extent than those of the sorbitol additive; it can be seen from examples 3 and 4 that the film stretch properties can be further improved with increasing glycerol content.

FIG. 3 is an AFM phase image characterization of comparative and example 1PEDOT PSS films with bright areas as PEDOT areas and dark areas as PSS areas in the phase image. It can be seen from the figure that with the addition of the additive, the separation of the bright and dark areas of the film is more and more obvious, which shows that more and more interactions occur among the PVA chains, the hydrophilic PSS segments and the polar sorbitol through hydrogen bonds, further the phase separation between PEDOT and PSS is promoted, the PEDOT is converted from the irregular coil conformation into the linear or extended coil conformation, and more PEDOT-PEDOT inter-chain connections are caused, which is very beneficial to charge transfer.

FIG. 4 is an AFM height map representation of comparative and example 1PEDOT PSS films showing that the addition of additives increases the area of the bright area representing the PEDOT area and increases the roughness of the film, indicating that the addition of sorbitol causes phase separation between the PEDOT and PSS areas, promotes aggregation of the PEDOT area, creates a better conductive path, and thus increases the conductivity of the film.

In conclusion, the PEDOT/PSS film prepared by the invention has the advantages of high conductivity, high transparency, good mechanical property and the like, and can be applied to flexible photoelectric devices as transparent conductive electrodes.

It should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and are not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. PSS film, characterized by that, it is formed by blending conductive polymer, water-soluble polymer as dopant and polyhydroxy compound;

PSS, polyvinyl alcohol and sorbitol or glycerol as the water-soluble polymer.

2. The highly conductive stretchable PEDOT PSS film according to claim 1 wherein the water soluble polymer polyvinyl alcohol content is 5wt% to 15wt% and the dopant sorbitol or glycerol content is 2wt% to 10wt%.

3. The highly conductive stretchable PEDOT PSS film according to claim 2 wherein the water soluble polymer polyvinyl alcohol content is 5wt% or 10wt%, the dopant sorbitol content is 4wt% or the dopant glycerol content is 8wt%.

4. PSS film, characterized in that it comprises the following steps:

5. The method for preparing highly conductive stretchable PEDOT: PSS film according to claim 4 wherein in step (1) the polymerization degree of the water soluble polymer polyvinyl alcohol is 1500-2400, the alcoholysis degree is 99%, and the concentration of the polyvinyl alcohol aqueous solution is 5wt%; the PEDOT prepared in the step (2) is that the PSS solution contains 5 to 15 weight percent of polyvinyl alcohol and 2 to 10 weight percent of sorbitol or glycerol.

6. The method for preparing a highly conductive stretchable PEDOT PSS film according to claim 5, wherein the PEDOT PSS solution prepared in the step (2) contains 5wt% or 10wt% of polyvinyl alcohol, and 4wt% of sorbitol or 8wt% of glycerin.

7. PSS film preparation method according to claim 4, characterized in that the heating agitation in step (1) is specifically at 90 ℃ at a speed of 500rpm/min to 700 rpm/min.

8. PSS film preparation method according to claim 4, characterized in that the heating agitation in step (2) is specifically at 90 ℃ at a speed of 1000rpm/min to 1200 rpm/min.

9. The method for preparing a highly conductive stretchable PEDOT: PSS film according to claim 4 wherein in step (3) the substrate is a hydrogenated styrene-butadiene block copolymer or a glass plate; the surface treatment of the substrate comprises sequentially cleaning the substrate with deionized water, acetone and isopropanol under ultrasound for 20min, and cleaning with an ultraviolet ozone cleaner for 25min; the spin coating is specifically 1000 rpm/min-3000 rpm/min for 60s; the annealing and drying temperature is 120-180 ℃, and the time is 15-30 min; the thickness of the obtained high-conductivity stretchable PEDOT, namely PSS film is 120 nm-200 nm.

10. Use of a highly conductive stretchable PEDOT PSS film as defined in any of claims 1-3 as a transparent conductive electrode in a flexible opto-electronic device.