High efficiency ITO-free hybrid solar cell using highly conductive PEDOT:PSS with co-solvent and surfactant treatments

Hybrid organic/inorganic heterojunction solar cells were fabricated based on polished n-type crystalline silicon (c-Si) and p-type transparent conducting polymer poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). The conductivity and wettability of PEDOT:PSS has been significantly improved by the addition of 5% dimethyl sulfoxide (DMSO) and 0.1% Capstone FS-31 surfactant. Transmission line measurements revealed that the sheet resistance of PEDOT:PSS with 5% DMSO is 122 O/sq, comparable to Indium-Tin Oxide (ITO). Quasi-steady-state photo-conductance measurements showed an implicit open-circuit voltage of 0.61 V with a minority carrier lifetime of 82 µs. The power conversion efficiency of the PEDOT:PSS/n-Si hybrid solar cells is 8.5% with an open-circuit voltage of 0.56 V, a short-circuit current density of 29.7 mA/cm2 and a fill factor of 49.7%.