PEDOT:PSS (or Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) is a transparent conductive polymer consisting of a mixture of the ionomers poly(3,4-ethylenedioxythiophene) carrying positive charges and polystyrene sulfonate carrying negative charges. Due to its unique combination of conductivity, transparency, ductility, and ease of processing, PEDOT:PSS has become a benchmark material in thin-film electronic fabrication.

Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate can be used as an interfacial layer for hole transport in organic light emitting diodes, organic photovoltaics, and perovskite photovoltaics. It can also be used as a replacement for transparent conductors such as ITO or FTO and is used commonly in applications where the underlying substrate is flexible.