Poly(3,4-ethylenedioxythiophene)

Poly(3,4-ethylenedioxythiophene) (PEDOT or PEDT; IUPAC name poly(2,3-dihydrothieno[3,4-b][1,4]dioxane-5,7-diyl)) is a conducting polymer based on 3,4-ethylenedioxythiophene or EDOT. It was first reported by Bayer AG in 1989.

Polymer

PEDOT possesses many advantageous properties compared to earlier conducting polythiophenes like 3-alkylthiophenes. For example, the polymer is optically transparent in its conducting state and has high stability, moderate band gap, and low redox potential. Its major disadvantage is its poor solubility, which is partly circumvented by use of composite materials such as PEDOT:PSS and PEDOT-TMA.

The polymer is generated by oxidation. The process begins with production of the radical cation of EDOT monomer, [C₂H₄O₂C₄H₂S]⁺. This cation adds to a neutral EDOT followed by deprotonation. The idealized conversion using peroxydisulfate is shown:

n C₂H₄O₂C₄H₂S + n (OSO₃)₂²⁻ → [C₂H₄O₂C₄S]_n + 2n HOSO₃⁻

Polymerization is usually conducted in the presence of polystyrene sulfonate (PSS), which acts as a template. PSS also provides a counter ion, which balances the charges in the reaction and hinders the formation of by-products such as 3,4-ethylenedioxy-2(5H)-thiophenone, and keeps the PEDOT monomers dispersed in water or aqueous solutions. The resulting PEDOT:PSS composite can be deposited on a conductive support such as platinum, gold, glassy carbon, and indium tin oxide.

Uses

Applications of PEDOT include electrochromic displays and antistatics.

PEDOT has also been proposed for photovoltaics, printed wiring, and sensors. PEDOT has been proposed for use in biocompatible interfaces.

Further reading

• Bello, A.; Giannetto, M.; Mori, G.; Seeber, R.; Terzi, F.; Zanardi, C. (2007). "Optimization of the DPV Potential Waveform for Determination of Ascorbic Acid on PEDOT-Modified Electrodes". Sensors and Actuators B: Chemical. 121 (2): 430. doi:10.1016/j.snb.2006.04.066. hdl:11380/621556.
• Kumar, S. Senthil; Mathiyarasu, J.; Phani, K. L. N.; Yegnaraman, V. (2005). "Simultaneous Determination of Dopamine and Ascorbic Acid on Poly(3,4-ethylenedioxythiophene) Modified Glassy Carbon Electrode". Journal of Solid State Electrochemistry. 10 (11): 905. doi:10.1007/s10008-005-0041-7. S2CID 95645292.
• Zhang, Xinyu; MacDiarmid, Alan G.; Manohar, Sanjeev K. (2005). "Chemical Synthesis of PEDOT Nanofibers". Chemical Communications (42): 5328–30. doi:10.1039/b511290g. PMID 16244744.

References

1. 3,4-Ethylenedioxythiophene
2. Transparent conducting film
3. PEDOT:PSS
4. Surface chemistry of neural implants
5. Conductive polymer
6. Polythiophene
7. Contamination
8. Polymer capacitor
9. Pseudocapacitor
10. Polyaniline
11. Glossary of fuel cell terms
12. Supercapacitor
13. Tantalum capacitor
14. Food contaminant
15. Electrochemical quartz crystal microbalance
16. Organic solar cell
17. Thermoelectric materials
18. PEDOT-TMA
19. Electrolytic capacitor
20. Photothermal therapy