Conductive polymers have been attracting attention for decades due to their promising applications in
photovoltaic cells and thermoelectrics. Among them, poly(3,4-ethylene dioxythiophene):poly(styrene
sulfonate) (PEDOT:PSS) is the most extensively studied one with the features of high water dispersibility,
transparency and thermal stability as well as having relatively high electrical conductivity (EC).
Nevertheless, the EC of as-prepared PEDOT:PSS is still unsatisfactory for real applications. Experimental
studies on PEDOT:PSS have showed that its low EC could be elevated by more than 3 to 4 orders of
magnitude by polar solvent treatment. However, the mechanism of this enhancement remains unclear.
In this work, dimethyl sulfoxide (DMSO) treated PEDOT:PSS polymers are studied using multiscale
molecular modeling, including density functional theory (DFT) calculations and molecular dynamics (MD)
simulations. We elucidate the mechanism of EC enhancement at the molecular level, demonstrating that
DMSO dissolves the PSS shell to release the conductive PEDOT in the core for self-aggregation, leading
to subsequent phase separation of PEDOT and PSS by charge screening. These findings are important for the
selection of alternative solvents for further EC enhancement of PEDOT:PSS in thermoelectric applications.
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Funding Info:
This work was supported by the A*STAR Science and Engineering Research Council (SERC) of Singapore (1527200024 and 1527200019).