poly(3,4-ethylenedioxythiophene)

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.{{cite journal |last1=Groenendaal |first1=L. |last2=Zotti |first2=G. |last3=Aubert |first3=P.-H. |last4=Waybright |first4=S. M. |last5=Reynolds |first5=J. R. |title=Electrochemistry of Poly(3,4-alkylenedioxythiophene) Derivatives |journal=Advanced Materials |date=5 June 2003 |volume=15 |issue=11 |pages=855–879 |doi=10.1002/adma.200300376|s2cid=95453357 }}{{cite journal |last1=Heywang |first1=Gerhard |last2=Jonas |first2=Friedrich |title=Poly(alkylenedioxythiophene)s—New, Very Stable Conducting Polymers |journal=Advanced Materials |date=1992 |volume=4 |issue=2 |pages=116–118 |doi=10.1002/adma.19920040213}} 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.{{cite journal |last1=Sun |first1=Kuan |last2=Zhang |first2=Shupeng |last3=Li |first3=Pengcheng |last4=Xia |first4=Yijie |last5=Zhang |first5=Xiang |last6=Du |first6=Donghe |last7=Isikgor |first7=Furkan Halis |last8=Ouyang |first8=Jianyong |title=Review on Application of PEDOTs and PEDOT:PSS in Energy Conversion and Storage Devices |journal=Journal of Materials Science: Materials in Electronics |date=July 2015 |volume=26 |issue=7 |pages=4438–4462 |doi=10.1007/s10854-015-2895-5|s2cid=137534972 }}

Applications of PEDOT include electrochromic displays and antistatics. PEDOT has also been proposed for photovoltaics, printed wiring, and sensors.{{cite journal|author1=Groenendaal, L. B. |author2=Jonas, F. |author3=Freitag, D. |author4=Pielartzik, H. |author5=Reynolds, J. R. |title=Poly(3,4-Ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future|journal=Adv. Mater.|year=2000|volume=12|issue=7|pages=481–494|doi=10.1002/(SICI)1521-4095(200004)12:7<481::AID-ADMA481>3.0.CO;2-C}}{{cite journal|author1=Kirchmeyer, S. |author2=Reuter, K. |title=Scientific Importance, Properties and Growing Applications of Poly(3,4-Ethylenedioxythiophene)|journal=J. Mater. Chem.|year=2005|volume=15|issue=21|pages=2077–2088|doi=10.1039/b417803n

}} PEDOT has been proposed for use in biocompatible interfaces.{{cite journal |last1=Donahue |first1=Mary J. |last2=Sanchez-Sanchez |first2=Ana |last3=Inal |first3=Sahika |last4=Qu |first4=Jing |last5=Owens |first5=Roisin M. |last6=Mecerreyes |first6=David |last7=Malliaras |first7=George G. |last8=Martin |first8=David C. |title=Tailoring PEDOT Properties for Applications in Bioelectronics |journal=Materials Science and Engineering: R: Reports |date=1 April 2020 |volume=140 |pages=100546 |doi=10.1016/j.mser.2020.100546 |s2cid=212425203 |language=en |issn=0927-796X|doi-access=free |hdl=10754/661510 |hdl-access=free }}{{cite news |last1=Cuthbertson |first1=Anthony |title=Material found by scientists 'could merge AI with human brain' |url=https://www.independent.co.uk/life-style/gadgets-and-tech/news/artificial-intelligence-brain-computer-cyborg-elon-musk-neuralink-a9673261.html |work=The Independent |date=17 August 2020 |language=en}}

Enhanced PEDOT's conductivity and surface area, making it a promising material for supercapacitors. Researchers at UCLA developed a nanofiber structure using a vapor-phase growth process, increasing its charge storage capacity nearly tenfold compared to conventional PEDOT. This new structure exhibited 100 times higher conductivity, a fourfold increase in surface area, and a charge storage capacity of 4600 mF/cm², while maintaining exceptional durability with over 70,000 charge cycles. These improvements enabled faster charging, greater efficiency, and longer lifespan, positioning PEDOT as a strong candidate for next-generation energy storage in renewable energy systems and electric vehicles.{{cite journal |last=Jimoh |first=Musibau Francis |display-authors=et al. |title=Direct Fabrication of 3D Electrodes Based on Graphene and Conducting Polymers for Supercapacitor Applications |journal=Advanced Functional Materials |date=23 July 2024 |doi=10.1002/adfm.202405569 }}

• {{cite journal|doi=10.1016/j.snb.2006.04.066|title=Optimization of the DPV Potential Waveform for Determination of Ascorbic Acid on PEDOT-Modified Electrodes|year=2007|last1=Bello|first1=A.|last2=Giannetto|first2=M. |last3=Mori|first3=G.|last4=Seeber|first4=R. |last5=Terzi|first5=F. |last6=Zanardi|first6=C.|journal=Sensors and Actuators B: Chemical|volume=121|pages=430|issue=2|hdl=11380/621556|hdl-access=free}}
• {{cite journal|doi=10.1007/s10008-005-0041-7|title=Simultaneous Determination of Dopamine and Ascorbic Acid on Poly(3,4-ethylenedioxythiophene) Modified Glassy Carbon Electrode|year=2005|last1=Kumar|first1=S. Senthil|last2=Mathiyarasu|first2=J.|last3=Phani|first3=K. L. N.|last4=Yegnaraman|first4=V.|journal=Journal of Solid State Electrochemistry|volume=10|pages=905|issue=11|s2cid=95645292}}
• {{cite journal|doi=10.1039/b511290g|pmid=16244744|title=Chemical Synthesis of PEDOT Nanofibers|year=2005|last1=Zhang|first1=Xinyu|last2=MacDiarmid|first2=Alan G.|last3=Manohar|first3=Sanjeev K.|journal=Chemical Communications|issue=42|pages=5328–30}}

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Category:Organic polymers

Category:Organic semiconductors

Category:Transparent electrodes

Category:Conductive polymers