PEDOT:PSS - Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate is a transparent conductive polymer consisting of a mixture of two ionomers. 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. PEDOT:PSS can be used as an interfacial layer for hole transport in organic light emitting diodes, organic photovoltaics, and perovskite photovoltaics.