Poly(3,4-ethylenedioxythiophene) (PEDOT) is a kind of heterocyclic conductive polymer, which has rapidly become a research hotspot in the field of functional materials once it is available. However, the eigen state of PEDOT is poorly soluble, which limits the application to a great extent. After doping of PSS, PEDOT can be well dispersed in aqueous solution, and then formed film with the advantages of high conductivity, light transmittance, heat resistance, and so on. This article will review the preparation and application of PEDOT:PSS.

Preparation of PEDOT:PSS

PSS contains amphoteric functional groups and sulfonic acid is a strong acid, so it can not only be used as a dispersant to improve the solubility of PEDOT, but also can improve the conductivity of PEDOT as a charge balancing agent. The PSS was dissolved in a certain amount of deionized water to which EDOT monomer was added dropwise with gentle stirring. Hydrochloric acid was added dropwise to control the pH value range of 2~3. Then slowly drip (NH4)2S2O8 and Fe2(SO4)3 mixed solution, rapid stirring reaction 24h. The anion and cation exchange resins were used to exchange inorganic salt ions for 4h, respectively, to obtain PEDOT:PSS solution in dark blue.

Applications of PEDOT:PSS

(1) Antistatic coating

Plastic and glass are prone to produce static charge in dry air and must be treated with antistatic. Antistatic is the earliest application of PEDOT:PSS as a conductive coating. PEDOT:PSS can be applied to film, glass, metal and other surfaces, further used in electronic packaging, electronic components, plastic housings, displays, rubber gloves or cloth, tape, and so on.

(2) Organic electroluminescence (LED)

Organic light-emitting diodes and polymer light-emitting diodes is currently the hot spot of display devices, it will be a powerful contender for the next generation of displays. Coating a layer of PEDOT:PSS on the anode ITO electrode can greatly improve the performance of the device: improve the luminous efficiency, reduce the open circuit voltage and prolong the life of the device. Through the modification of PEDOT:PSS, it can improve the stability of the electrode and the performance of the device.

(3) solar cells

Compared with traditional inorganic batteries, polymer solar cells have the advantages of light weight, low cost, large-area wet-process film-forming and flexible devices. PEDOT:PSS are mainly embodied in the following aspects: as a transparent conductive layer deposited on the surface of the electrode active layer or deposited on the surface of the electrode substrate; on the other hand as a buffer layer deposited between the transparent electrode and the active layer.

(4) Electrochromic materials

Electrochromic conductive polymer research is an important area of electrochromic research. The excellent processability of PEDOT:PSS waterborne coatings offers the possibility of manufacturing large-area electrochromic devices on a large scale. Such materials can be applied to electrochromic smart windows, electrochromic displays, non-glinting mirrors, electrochromic storage devices, infrared emitting devices, radar absorbing materials and other fields.

(5) Solid capacitors

The outstanding high temperature stability of PEDOT:PSS makes its surface resistance stable at 280°C. Capacitor cathode material using PEDOT:PSS film, on the one hand can significantly reduce the equivalent series capacitor ESR, improve capacity-frequency, impedance-frequency characteristics; the other hand, it also has a long life, miniaturization, high reliability. And the production process of PEDOT:PSS is no by-products, easy to control, and does not occur other unrelated chemical polymerization, it will not affect the performance of the product.

(6) Thermoelectric conversion material

Relative to inorganic materials, PEDOT:PSS has the advantages of light weight, good elasticity, easy processing and abundant resources, rich electronic band structure, both plastic properties and electronic properties of metals or semiconductors, good stability and transparency.

(7) chemical biosensors

As a sensing material, PEDOT:PSS composite has the advantages of stable and reversible structure, good electrochemical activity, good biocompatibility, combination with different preparation methods and different materials.

(8) anti-corrosion coating

PEDOT:PSS coatings combine physical and chemical properties such as electrical conductivity, environmental stability and reversible redox properties to activate the metal surface and catalyze the formation of dense oxide passivating films that effectively shield the corrosive media from corrosion associated with the metal matrix Further contact.

PEDOT:PSS coating has the advantages of strong conductivity, good film quality, good transparency, high optical contrast, high stability, strong adhesion, variable color of the film, good cycling and durability, and has been the core of the field of research, we believe that with the continuous improvement of social requirements and the deepening of research, its application areas will further expand.