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Abstract
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Poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) is a transparent conductive material and a good candidate for being employed as substitute for indium tin oxide (ITO) in reducing the production costs of organic solar cells. To enhance
the performance of organic devices, an improving in the conductivity of PEDOT:PSS is crucial and using the solvent additive rises
the electrical conductivity by the optimization of the film morphology. The studies have only focused on the relationship between
the electrical conductivity of thin films and the crystallinity of PEDOT, and it is also found that the high conductivity is observed in
the highly crystalline samples. This study focused on the effect of tacticity of PS on the conductivity of PEDOT:PSS films. First,
atactic and isotactic polystyrenes were sulfonated and the complexes of PEDOT:PSS were synthesized. The N-methylpyrrolidone
(NMP), as a secondary dopant, was then added to the complexes and conductivity enhancement was investigated in various
annealing times. The obtained films were characterized by atomic force microscopy, X-ray diffraction, four point probe resistivity
measurement system, UV–visible spectroscopy, FT-IR, and cyclic voltammetry. The electrical conductivity of PEDOT:iPSS films
synthesized by the isotactic polystyrene was ~ 0.68 S/cm and by adding 5 wt% NMP into PEDOT:PSS solution, the conductivity of
the annealed thin layers increased more than 10-folds (~ 7.73 S/cm) at an appropriate temperature.
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