Near 5% DMSO is the best: A structural investigation of PEDOT: PSS thin films with strong emphasis on surface and interface for hybrid solar cell

Effect of dimethyl sulfoxide (DMSO) doping on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films have been optimized for obtaining better hole transport layer in hybrid solar cell. The correlation between morphology and conductivity is established through atomic force microscopy and transmission length method measurements. On the other hand, change in the shape of the building blocks (from spheroidal-like to ellipsoidal-like) in the PEDOT:PSS films with DMSO concentration is apparent from their electron density profiles and topographies, suggesting possible conformational change (from coil-like to rod-like) in film by X-ray reflectivity. Such change is further evident from their compositional profiles, work functions and electronic band structures estimated from X-ray and ultraviolet photoelectron spectroscopies. In fact, complementary information suggest that near 5% DMSO doped PEDOT:PSS film is governed through maximum in-plane extended ellipsoidal-like blocks as well as well-organized in out-of-plane ordering which is likely to be the optimum structure for increased the highest electrical conductivity up to 1230¿S/cm. Finally, maximum power conversion efficiency of 11% with open-circuit voltages around 600¿mV, a short-circuit current density higher than 30¿mA/cm2 and a fill factor of 59.4% is achieved for the 5% DMSO doped PEDOT:PSS/n-Si hybrid solar cell, which is perfectly correlated with their structure.