Recent Advances of Synthesis, Properties, Film Fabrication Methods, Modifications of Poly(3,4‐ethylenedioxythiophene), and Applications in Solution‐Processed Photovoltaics

Abstract Poly(3,4‐ethylenedioxythiophene) (PEDOT) is a very unique polymer. It can be very conductive, highly transparent, and environmentally stable. It is highly switchable between its oxidation state and neutral state. It forms a micellar complex with polystyrene sulfonate in aqueous conditions, and then can be solution‐processible and printable. Based on these advantages, PEDOT has been widely used as conductors and transparent electrodes in electronics and optoelectronics. The device performance is highly correlated with the structure and properties of PEDOT. In this review, advances in the synthesis, optoelectronic and chemical properties are comprehensively described and analyzed, as well as the strategies for tuning these properties to fulfill the requirement for device applications. Film processing techniques (printing and transfer printing) for the conducting polymer are also presented. Then, the applications of PEDOT as conductors for versatile organic and perovskite solar cells (single‐junction, tandem, semitransparent, colorful, flexible and ultraflexible, fully printed solar cells) are summarized. Finally future study directions for PEDOT in terms of conductivity enhancement and application‐oriented formulations are discussed.