PEDOT:PSS morphology is shown to be sensitive to the initial distribution of PEDOT and PSS in the solution, and the results of the modelling suggest that the experimentally observed granular structure of PEDOT:PSS can be only obtained if PEDOT/PSS solution is in the dispersive state on the initial crystallization stages. The variation of the pH is demonstrated to strongly affect the morphology of PEDOT:PSS films altering their structure between granular-type and homogeneous one. It also affects the size of crystallites and the relative arrangement of PEDOT and PSS chains. It is shown that the crystallites in PEDOT:PSS are smaller than those in PEDOT with molecular counterions such as PEDOT:Tosylate, which is consistent with available experimental data.

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