Consequences of gamma-ray irradiation on structural and electronic properties of PEDOT:PSS polymer in air and vacuum environments

In this work, the effects of gamma-ray irradiation (up to 3 kGy) on the structural and electronic properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), irradiated in air and vacuum environments are systematically investigated. Raman spectroscopy indicates that there is no significant change in structural conformation of PEDOT:PSS film after gamma-ray irradiation. However, the conductivity of the film decreases as a function of dose in both air and vacuum environments, which can be deduced as a result of defects created in the structure. Hall effect measurements showed higher carrier concentration when the samples are irradiated under vacuum in comparison to the air environment, whereas mobility decreases as a function of dose irrespective of the environment. Furthermore, the electron spin resonance spectra provided evidence of the evolution of polaron population after gamma-ray exposure of 3 kGy, due to the decrease in charge delocalization and molecular ordering of the molecules. This decrease in conductivity and mobility of the PEDOT:PSS films irradiated in air and vacuum environments can be mainly ascribed to the defects and radical formation after gamma-ray exposure, favoring chain scission or cross-linking of the polymers.