Study of electrical conductivity of PEDOT:PSS at temperatures >300 K for hybrid photovoltaic applications

Temperature dependence of DC conductivity σDC(T) of spin-coated poly (3,4 ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) films has been studied. σDC(T) was measured in films deposited from mixtures of PEDOT/PSS: H₂O (1:0.5), PEDOT:PSS (without dilution), PEDOT/PSS: Isopropyl Alcohol (IPA) (1:0.5) and PEDOT/PSS:IPA (1:1). Room temperature conductivity σ_RT of PEDOT/PSS films is enhanced from 4.46×10^-5 S/cm to 6.07×10^-4 S/cm after dilutions with H₂O and IPA (1:1), respectively. Experimental data is fitted with two different transport models: thermal activated conduction and variable range hopping (VRH) model. It is found that σ_DC(T) of PEDOT/PSS:IPA (1:1) sample can be described by the one-dimensional (1D) VRH model with an pre-exponential factor σ₀=28.5 S/cm and material-dependent parameter T₀=39,204 K.