LAUSR

Abstract Accelerated thermal ageing studies were carried out on poly(3,4ethylenedioxythiophene): poly(styrene sulfonate)(PEDOT:PSS) thin films upto 150 °C to predict its life-time. The effect of thermal ageing on the chemical structure and the electronic structure is investigated. Changes in the conductivity of PEDOT:PSS films with ageing are studied along with UV–Vis, ATR-FTIR, Raman spectroscopy and AFM analysis. Conductivity at different temperatures shows an exponential decrease with time in the case of PEDOT:PSS (1.6PSS). Based on this data, the life-time of PEDOT:1.6PSS thin films at ambient conditions is predicted. The analysis of changes in the chemical structure using FTIR spectroscopy and the corresponding changes in the electronic structure using UV–Vis data shows changes in the polaronic states during ageing. Corresponding changes in the Raman spectroscopy data show oxidized-neutral transitions occurring during ageing which results in the conductivity changes. It is observed that unidirectional shearing of PEDOT:1.6PSS dispersion during film formation improved the thermal ageing characteristics. The ageing resistance of these films became comparable to that of PEDOT:2.5PSS films with higher PSS ratio. AFM studies show the effect of ageing on the surface morphology of films and shearing of films during formation can result in better ageing resistance and stable morphology.