Poly(3,4-ethylenedioxythiophene) explained

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.^[1]

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.^{[2] [3]} Its major disadvantage is its poor solubility, which is partly circumvented by use of composite materials such as 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.^[4]

Uses

Applications of PEDOT include electrochromic displays and antistatics.

PEDOT has also been proposed for photovoltaics, printed wiring, and sensors.^{[5] [6]} PEDOT has been proposed for use in biocompatible interfaces.^{[7] [8]}

Further reading

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

Notes and References

1. EP. 0339340A2. Patent. Polythiophenes, Process for Their Preparation and Their Use. 1989-11-02. 1999-12-29. 1989-04-08. Friedrich Jonas, Gerhard Heywang, Werner Schmidtberg, Jürgen Heinze, Michael Dietrich. BAYER AG.
2. Groenendaal . L. . Zotti . G. . Aubert . P.-H. . Waybright . S. M. . Reynolds . J. R. . Electrochemistry of Poly(3,4-alkylenedioxythiophene) Derivatives . Advanced Materials . 5 June 2003 . 15 . 11 . 855–879 . 10.1002/adma.200300376. 95453357 .
3. Heywang . Gerhard . Jonas . Friedrich . Poly(alkylenedioxythiophene)s—New, Very Stable Conducting Polymers . Advanced Materials . 1992 . 4 . 2 . 116–118 . 10.1002/adma.19920040213.
4. Sun . Kuan . Zhang . Shupeng . Li . Pengcheng . Xia . Yijie . Zhang . Xiang . Du . Donghe . Isikgor . Furkan Halis . Ouyang . Jianyong . Review on Application of PEDOTs and PEDOT:PSS in Energy Conversion and Storage Devices . Journal of Materials Science: Materials in Electronics . July 2015 . 26 . 7 . 4438–4462 . 10.1007/s10854-015-2895-5. 137534972 .
5. Groenendaal, L. B. . Jonas, F. . Freitag, D. . Pielartzik, H. . Reynolds, J. R. . Poly(3,4-Ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future. Adv. Mater.. 2000. 12. 7. 481–494. 10.1002/(SICI)1521-4095(200004)12:7<481::AID-ADMA481>3.0.CO;2-C.
6. Kirchmeyer, S. . Reuter, K. . Scientific Importance, Properties and Growing Applications of Poly(3,4-Ethylenedioxythiophene). J. Mater. Chem.. 2005. 15. 21. 2077–2088. 10.1039/b417803n.
7. Donahue . Mary J. . Sanchez-Sanchez . Ana . Inal . Sahika . Qu . Jing . Owens . Roisin M. . Mecerreyes . David . Malliaras . George G. . Martin . David C. . Tailoring PEDOT Properties for Applications in Bioelectronics . Materials Science and Engineering: R: Reports . 1 April 2020 . 140 . 100546 . 10.1016/j.mser.2020.100546 . 212425203 . en . 0927-796X. free . 10754/661510 . free .
8. News: Cuthbertson . Anthony . Material found by scientists 'could merge AI with human brain' . The Independent . 17 August 2020 . en.