A pedot dispersion liquid conductive material and a method for preparing the same

Abstract

The application provides a PEDOT dispersion liquid conductive material, the main body of which is a complex of PEDOT and PPP-OPSO3; monomer EDOT is polymerized in a PPP-OPSO3 aqueous solution treated by a cationic resin under the action of iron p-toluic acid and sodium persulfate, and the reaction solution is treated by a cationic and anionic resin to obtain a PEDOT / PPP-OPSO3 aqueous dispersion liquid. The material can be applied to electronic, optoelectronic and other devices requiring organic conductive functions.

Description

Technical Field

[0001] This invention relates to the field of organic polymer conductive materials technology, and in particular to a PEDOT dispersion conductive material and its application in electronic and optoelectronic devices. Background Technology

[0002] Organic conductive polymers are finding increasingly widespread applications in supercapacitors, printed electronics, and organic solar cells. Poly(3,4-ethylenedioxythiophene) (PEDOT), a high-performance conductive polymer, boasts a conductivity of up to 4000 S / cm and exhibits excellent environmental stability and high visible light transmittance. However, like other common conductive polymers, PEDOT is an insoluble and infusible polymer solid, significantly limiting its applications. Typically, it requires doping with the water-soluble polymeric electrolyte polystyrene sulfonate (PSS). The polymerized PEDOT molecular chains are grown on a PSS molecular template to obtain an aqueous dispersion of the PEDOT / PSS (poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate) composite for further processing. Although PSS is a rare water-soluble polymer that Bayer and Agfa have successfully developed to match PEDOT, PSS itself, as a water-soluble polyanionic electrolyte, has less than ideal conductivity, diluting the conductivity and stability of PEDOT itself. Furthermore, to achieve the desired high conductivity, highly polar solvents such as dimethyl sulfoxide (DMSO), ethylene glycol (EG), and even soluble ionic liquids and sulfuric acid need to be added to PEDOT / PSS as secondary dopants. However, the introduction of these substances typically limits the application of PEDOT / PSS due to issues with biotoxicity and dispersion stability, including various other conductive materials that molecularly modify PEDOT or PSS. To overcome these drawbacks, research is underway to explore better alternatives to PSS, such as using perfluorosulfonic acid polymers (PFSA). However, this leads to instability issues in devices, such as reduced solid-state capacitor withstand capability. Therefore, it is necessary to consider developing other alternatives to PSS. Summary of the Invention

[0003] This invention aims to provide a PEDOT dispersion conductive material and its preparation method, thereby solving the aforementioned problems existing in the current PEDOT / PSS technology.

[0004] The present invention is achieved by the following technical solution: a PEDOT dispersion conductive material, which is a composite aqueous dispersion composed of PEDOT and PPP-OPSO3, wherein the weight ratio of PEDOT and PPP-OPSO3 is 1:0.1-1:25.

[0005] Furthermore, the weight ratio of PEDOT to PPP-OPSO3 is 1:0.25-1:6.

[0006] Furthermore, the weight ratio of PEDOT to PPP-OPSO3 is 1:0.5-1:2.

[0007] The PPP-OPSO3 is a (poly(2,5-bis(3-sulfonylpropoxy)-1,4-phenylene,-alt-1,4-phenylene)) salt, with the following molecular structure:

[0008]

[0009] M is a substituent, such as sodium metal, H, or CH3.

[0010] PPP-OPSO3 belongs to the poly(p-phenylene) group and possesses the chemical resistance and heat resistance of polytetrafluoroethylene (PTFE). PPP-OPSO3 is a highly soluble conjugated polyelectrolyte with inherent conductivity and thermal stability. Structurally, PPP-OPSO3 and PSS have similar molar ratios of sulfonic acid groups, but PPP-OPSO3 exhibits a conjugated structure on its polymer chain, thus resulting in more stable conductivity and better temperature resistance. The inventors unexpectedly discovered that PPP-OPSO3 can partially replace PSS under certain conditions, generating a PEDOT / PPP-OPSO3 composite aqueous dispersion with certain self-emulsifying and film-forming properties, thus enhancing the conductivity and stability of PEDOT-based composite polymer materials at the molecular structure level.

[0011] The present invention further provides a method for preparing the above-mentioned PEDOT dispersion conductive material, wherein the PEDOT / PPP-OPSO3 aqueous dispersion is prepared by polymerization of monomer EDOT (3,4-ethylenedioxythiophene) in PPP-OPSO3 aqueous solution under the presence of iron salt and oxidant.

[0012] Furthermore, the iron salt is an inorganic ferric salt or an organic sulfonate ferric salt, such as ferric sulfate, ferrous sulfate, ferric chloride, ferrous chloride, ferric p-toluenesulfonate, and ferric polystyrenesulfonate; the oxidant is a persulfate, such as sodium persulfate, potassium persulfate, and ammonium persulfate.

[0013] Furthermore, PPP-OPSO3 is treated with cation exchange resin before feeding to purify and remove cations.

[0014] Furthermore, the monomer EDOT is emulsified into an emulsion in PPP-OPSO3 water-soluble liquid under high-speed shear stirring, ultrasonic field, or both before polymerization, which is beneficial for obtaining better photoelectric properties of the dispersion.

[0015] Furthermore, the PEDOT conductive material is used in electronic or optoelectronic devices to improve energy density and power density in supercapacitors, enhance durability and stability in solid-state capacitors, improve sensitivity and selectivity in electrochemical sensors, and serve as a functional conductive material in conductive films for printed electronics.

[0016] Compared with existing technologies, this technical solution has the following advantages:

[0017] 1. This invention provides a novel PEDOT dispersion conductive material that can partially replace PSS, enhancing the conductivity and stability of PEDOT conductive materials in some applications and expanding the application range of PEDOT conductive materials.

[0018] 2. The preparation method of PEDOT / PPP-OPSO3 aqueous dispersion provided by the present invention is relatively simple, realizing the practicality of the invention. Attached Figure Description

[0019] Figure 1 These are the infrared spectra of PPP-OPSO3, PEDOT / PSS OE-003, and PEDOT / PPP-OPSO3 (1:1);

[0020] Figure 2 The curves show the number of cycles and specific capacitance of PEDOT / PSS OE-003 and PEDOT / PPP-OPSO3 (2:1) in constant current charge-discharge at a current density of 0.5 A / g. Detailed Implementation

[0021] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0022] Unless otherwise specified, all instruments and raw materials used in this invention are conventional commercial instruments or materials. Specifically, EDOT (99.5% from Bailey Technology (Chongqing) Co., Ltd.), Fe(OTs)3 p-toluenesulfonate (99% from Shanghai Ouyi Organic Optoelectronic Materials Co., Ltd.), sodium persulfate Na2S2O8 (analytical grade from Sinopharm Chemical Reagent Co., Ltd.), and PEDOT / PSS (OE-003 from Shanghai Ouyi Organic Optoelectronic Materials Co., Ltd.) are all commercially available. Sodium PPP-OPSO3, GPC molecular weight 30000, was prepared according to the literature (Kim, Seungho; Jackiw, Jennifer; Robinson, Edward; Schanze, Kirk S.; Reynolds, John R.; Baur, Jeff; Rubner, Michael F.; Boils, Danielle (1998). Water Soluble Photo- and Electroluminescent Alkoxy-Sulfonated Poly(p-phenylenes) Synthesized via Palladium Catalysis. Macromolecules, 31(4), 964–974.).

[0023] Unless otherwise mentioned, all detection indicators involved in the embodiments of the present invention are detected using conventional detection methods in the art.

[0024] Example 1

[0025] In a 250 ml three-necked flask, 0.6 g of PPP-OPSO3 was dissolved in 5 ml of deionized water and passed through a cation exchange resin column. The filtrate was diluted with deionized water to 100 ml, and then 0.3 g of EDOT was added. The mixture was stirred thoroughly to disperse the EDOT. 20 ml of a 2.86 mol / L aqueous solution of ferric p-toluenesulfonate and sodium persulfate in an equimolar ratio with EDOT were added in one step. The reaction was carried out at room temperature for 20 h, during which the liquid gradually turned a deep blue-ink color. 20 g of a mixed anion and cation exchange resin was added, and the mixture was stirred for 5 h. The mixture was then filtered through a 400-mesh filter to remove the resin, yielding approximately 90 g of a deep blue PEDOT / PPP-OPSO3 1:2 dispersion.

[0026] Example 2

[0027] Add 0.6g of EDOT, following the same steps as in Example 1, to obtain approximately 90g of a dark blue PEDOT / PPP-OPSO3 1:1 dispersion.

[0028] Example 3

[0029] Add 1.2g of EDOT, following the same steps as in Example 1, to obtain approximately 90g of a dark blue PEDOT / PPP-OPSO3 2:1 dispersion.

[0030] Comparative Example

[0031] Shanghai Ouyi Organic Optoelectronic Materials Co., Ltd.'s PEDOT / PSS dispersion product OE-003.

[0032] Structural analysis of PEDOT / PPP-OPSO3: The PEDOT / PPP-OPSO3 dispersion was mixed with excess potassium bromide, dried in a vacuum oven at 50°C for 6 hours, and then ground and mixed thoroughly. The mixture was then compressed into tablets using a tablet press. Fourier transform infrared spectroscopy (FTIR, TENSOR27, Bruker GmbH, Germany) was performed on the tablets to determine their functional groups.

[0033] Physicochemical property analysis of PEDOT / PPP-OPSO3: The viscosity of the dispersion was measured using a rotational viscometer (NDJ-8S, Shanghai Lichen Instrument Co., Ltd.) with rotor No. 1 at a constant temperature of 25 degrees Celsius. The dispersion was diluted 10 times with deionized water, sonicated for 30 min, and its particle size was analyzed using a nanolaser particle size analyzer (ZetasizerNanoZS, Malvern Panaco Instrument Co., Ltd.). Its solid content was determined using a rapid moisture analyzer (LC-DHS-20A, Shanghai Lichen Instrument Co., Ltd.). The sodium ion content in the dispersion was determined using a sodium ion analyzer (DWS-51, Shanghai Instrument & Electronics Scientific Instrument Co., Ltd.).

[0034] Conductivity determination of PEDOT / PPP-OPSO3: A 10x10mm glass slide was cleaned twice (15 min each time) in an ultrasonic bath using detergent, deionized water, acetone, and isopropanol. Afterward, it was thoroughly dried in a hot drying oven. The pre-cleaned substrate was then treated with ultraviolet ozone (UVO) for 20 min. A PEDOT / PPP-OPSO3 and PEDOT / PSS (OE-003) film of approximately 15 nm thickness was then deposited on the glass slide surface via spin coating (4000 rpm). (Both dispersions were diluted with ultrapure water at a 1:1 ratio before use). The film was then heat-annealed at 150°C for 20 min to form a thin film. After drying, the surface resistance of the conductive film was measured using a four-probe tester (ST2253, Suzhou Jingge Electronics Co., Ltd.).

[0035] Figure 1 The infrared spectrum of the polymer in the case of PEDOT / PPP-OPSO3 1:1 is shown in the figure. 3453 cm⁻¹ is the absorption peak of the hydroxyl group (-OH) of the sulfonic acid composition in PPP-OPSO3 in the polymer PEDOT / PPP-OPSO3 (1:1). 2939, 2878, and 2826 cm⁻¹ are also shown.-1 These are the absorption peaks of the carbon-hydrogen bonds in the sulfonic acid molecule of PPP-OPSO3, respectively; 1513, 1329 cm⁻¹. -1 The absorption peaks at these points are due to the C=C and C=C double bonds on the thiophene ring, at 1192 and 1051 cm⁻¹. -1 There are asymmetric and asymmetric absorption peaks for carbon-oxygen-carbon (COC), at 978, 920, and 685 cm⁻¹. -1 These are characteristic absorption peaks of PEDOT. The IR spectrum shows that PPP-OPSO3 and PEDOT exist as a molecular complex.

[0036] Table 1. Physicochemical data of PEDOT / PPP-OPSO3 dispersion obtained in the examples and PEDOT / PSS in the comparative example.

[0037]

[0038] Table 1 compares the physicochemical data of PEDOT / PPP-OPSO3 dispersions prepared with different ratios and a comparative PEDOT / PSS OE-003 dispersion prepared using a similar method. The table shows that as the PPP-OPSO3 content increases, the viscosity of the dispersion decreases, and the particle size tends to decrease. Furthermore, the film observed under electron microscopy is smoother. PEDOT / PPP-OPSO3 has a smaller particle size than PEDOT / PSS, offering advantages in electronic and optoelectronic applications. This indicates that PSS has a lower affinity for PEDOT compared to PPP-OPSO3. From a molecular structure perspective, PSS, with its benzenesulfonic acid-branched structure, has greater steric hindrance than PPP-OPSO3, which has a straight-chain sulfonic acid structure. The overall sodium ion concentration is below 10 ppm, indicating that impurities in the system have been largely removed, meeting the manufacturing process requirements for electronic-grade products. In terms of conductivity, PEDOT / PPP-OPSO3 exhibits a resistance an order of magnitude lower than PEDOT / PSS without the addition of polar solvents. Furthermore, the resistance tends to decrease further with increasing PEDOT molar ratio. This suggests that the conjugated polyelectrolyte mixed framework of PPP-OPSO3 improves the overall conductivity of PEDOT compared to the PSS polyelectrolyte framework. Overall, the PEDOT / PPP-OPSO3 dispersion shows promising prospects for electronic and optoelectronic applications.

[0039] Application Examples

[0040] To further verify the applicability of the PEDOT / PPP-OPSO3 dispersion of the present invention and its impact on device performance, it was fabricated into an electrode device for material comparison verification. Specifically, the PEDOT / PPP-OPSO3 (2:1) dispersion obtained in Example 3 was dispersed in water with carbon nanofibers (CNF) at an equal mass ratio. To meet the requirements for testing equivalent comparative devices, 10% DMSO was added at a consistent volume ratio, and the mixture was ultrasonically dispersed for 30 minutes to obtain a homogeneous dispersion. This dispersion was then mixed with polyvinylidene fluoride (PVDF) emulsion at an equal mass ratio. This ternary dispersion was dripped onto the surface of a 304 stainless steel wire mesh, spread evenly, and then dried at 120 degrees Celsius for 40 minutes to obtain the working electrode.

[0041] The above are the working electrodes, with a matching platinum electrode as the counter electrode and a saturated calomel electrode as the reference. A 1M sulfuric acid aqueous solution was used as the electrolyte. Cyclic voltammetry was used to determine the voltage window of -0.2 to 0.8 V using an electrochemical workstation (CHI660E, Shanghai Chenhua Instrument Co., Ltd.), with scan rates of 10 mV / s, 25 mV / s, 50 mV / s, and 100 mV / s. Different charge-discharge tests were also conducted using a constant current charge / discharge (CP) test within the 0–0.8 V voltage window.

[0042] Figure 2 The curves show the comparison of the number of cycles and specific capacitance of PEDOT / PSS OE-003 and PEDOT / PPP-OPSO3 (2:1) in constant current charge-discharge at a current density of 0.5A / g.

[0043] Constant current charge-discharge testing involves applying a constant current to an electrochemical system to test its charging and discharging processes. This method can evaluate the capacitive performance, electrochemical energy storage performance, and kinetic characteristics of electrochemical reactions in materials or systems. By measuring voltage changes during charging and discharging, parameters such as the electrochemical system's capacitance, energy storage efficiency, and cycle stability can be determined. Figure 2 As shown, the specific capacity, cycle stability and charge / discharge time of PEDOT / PPP-OPSO3 (2:1) are still superior to those of the comparative PEDOT / PSS OE-003 under the same doping conditions of DMSO and sulfuric acid, indicating that the overall energy absorption is proportional to the content of PEDOT and its own conductivity.

[0044] The invented PEDOT / PPP-OPSO3 dispersion has good conductivity, stability and cycle durability, and can be applied to a variety of electronic and optoelectronic devices that require specific organic conductive functions.

[0045] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The scope of patent application of the present invention should not be limited by these embodiments. That is, any equivalent changes or modifications made in accordance with the spirit disclosed in the present invention still fall within the patent scope of the present invention.

Claims

1. A conductive material for PEDOT dispersion, characterized in that: An aqueous dispersion composed of PEDOT and PPP-OPSO3, wherein the weight ratio of PEDOT to PPP-OPSO3 is 1:0.1-1:

25.

2. The PEDOT dispersion conductive material as described in claim 1, characterized in that: The weight ratio of PEDOT to PPP-OPSO3 is 1:0.25-1:

6.

3. The PEDOT dispersion conductive material as described in claim 1, characterized in that: The weight ratio of PEDOT to PPP-OPSO3 is 1:0.5-1:

2.

4. The method for preparing the PEDOT dispersion conductive material according to any one of claims 1-3, characterized in that: A PEDOT / PPP-OPSO3 aqueous dispersion was prepared by polymerization of monomer EDOT in an aqueous solution of PPP-OPSO3 under the presence of iron salt and oxidant.

5. The method according to claim 4, characterized in that: The iron salt is an inorganic ferric acid salt or an organic ferric sulfonate salt, and the oxidizing agent is a persulfate.

6. The method according to claim 4, characterized in that: PPP-OPSO3 is treated with cation exchange resin before being fed into the reactor.

7. The method according to claim 4, characterized in that: The monomer EDOT is first emulsified in PPP-OPSO3 aqueous solution under high-speed shear stirring or ultrasonic field before subsequent polymerization reaction.

8. The application of the PEDOT dispersion conductive material according to any one of claims 1-3 in electronic or optoelectronic devices.

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