Spin transport in heavily doped PEDOT:PSS with tunable electrical conductivity*

Among pi-conjugated conducting polymers, doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, or PEDOT:PSS, has been widely used in optoelectronic devices. Interestingly the PEDOT:PSS electrical conductivity can vary substantially between 10-3 S/cm to 103 S/cm depending on the doping concentration determined by the solvents and additives used. We report a comparative studies of the spin diffuse lengths, spin relaxation times and charge motilities in different PEDOT:PSS compounds with various conductivities using the techniques of spin-pumping, electron spin resonance and field effect transistor, respectively. In particular we contrast the charge transport and spin transport in these materials.