Investigation of Conductivity Loss in LbL Assembled PEDOT:PSS Films

摘要

Conjugated polymers are employed as organic semiconductors in devices such as organic light emitting diodes, organic photovoltaics, thin-film transistors, capacitors, sensors, and electrochromic devices. Due to limited environmental stability, brittleness, inflexibility, and insolubility, these polymers are often tough to process and their use is impractical. On the other hand, poly(3,4-ethylenedioxythiophene) :poly(styrenesulfonate) (PEDOT:PSS), a conjugated polymer that is supplied as an aqueous dispersion, is easy to process, and is characterized by high environmental stability, transparency and good flexibility. It has been estimated that every fourth 3,4- ethylenedioxythiophene repeat unit of PEDOT complexes ionically with a styrenesulfonate group from the PSS to generate doped conductive polymer. The excess anionic charge along the PSS backbone stabilizes PEDOT:PSS in water, and facilitates facile deposition on cationically charged substrates via electrostatic layer-by-layer (LbL) assembly.