Performance of Si/PEDOT:PSS Hybrid Solar Cell Controlled by PEDOT:PSS Film Nanostructure

A hybrid solar cell composed of a crystalline semiconductor and polymer film has attracted much attention due to numerous advantages, such as high mobility, long lifetime, and the aqueous solution processing. Recently, the power conversion efficiency (PCE) of the hybrid solar cell of silicon (Si) wafer and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is reported to be higher than that of a commercial amorphous Si solar cell. Here in the Si/PEDOT:PSS hybrid solar cell was prepared using dimethyl sulfoxide (DMSO) as an additive to the PEDOT:PSS solution. The PCE was increased up to 10-fold by the addition of DMSO at a concentration of 5 wt%. Results from grazing-incidence X-ray diffraction, atomic force microscopy, and Raman spectroscopy indicated the 10-fold enhancement was controlled by the nanostructure of the PEDOT:PSS film. The enhanced performance was attributed to (i) an increase of π–π stacking, (ii) shortened distances between π–π planes, (iii) an increase in the quinoid structure of PEDOT, and (iv) reduced PEDOT:PSS particle size. The PCE was also enhanced by a transparent cathode of colloidal Ag nanowires and through the use of a vacuum-free process for preparation of the PEDOT:PSS film.