The optical and electrical properties of the blending organic film poly­(3,4-ethylenedioxy-thiophene):poly­(styrenesulfonate) (PEDOT:PSS) are strongly affected by its morphology, resulting in the performance variation in Si/organic hybrid solar cells. Here, a facile postsolvent treatment is used to tailor the vertical morphology of PEDOT:PSS by introducing a nonpolar solvent. X-ray photoelectron spectroscopy depth-profiling measurements show that the distribution of PEDOT and PSS on the surface of n-type Si can be changed by nonpolar solvent n-hexane (NHX) treatment, where more PSS aggregate at the bottom of the blend film and more PEDOT float up to the top, as compared with the reference sample. As a result, after NHX treatment, the average lifetime of the Si/organic films is increased from 152 μs for untreated samples to 248 μs for NHX-treated ones because of the better passivation effect of PSS on Si. Moreover, the transmission line model measurements indicate that the contact resistance (R C) of PEDOT:PSS film and the Ag electrode is decreased for better charge collection after NHX treatment. Eventually, the best power conversion efficiency (PCE) of 13.78% for NHX-treated planar solar cells is obtained, much higher than the PCE (with best of 12.78%) of reference devices without nonpolar solvent treatment. Our results provide a facile method to tailor the vertical morphology of the PEDOT:PSS in Si/organic hybrid solar cells.

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The contact quality between Si and the rear electrode and the passivation of Si play crucial roles in efficient organic/Si hybrid solar cells, especially for the open-circuit voltage (V OC ). Herein, we reported a dual bilayer structure to synergistically improve both rear contact quality and passivation of Si to enhance the performance of organic/planar-Si hybrid solar cells. Series resistance (R S ) extracted by the double diode model, contact quality explored by the Cox and Strack (CS) method, and the work function measured by ultraviolet photoelectron spectroscopy (UPS) revealed that the work function of the rear electrode effectively decreased after adding a metallic bilayer at the interface between Si and the rear electrode, which reduced the contact barrier, led to an Ohmic contact, and facilitated the transportation of electrons. Moreover, the minority carrier lifetime increased from 138.81 to 252.89 μs after applying a surfactant on top of the organic film because of the improved passivation effect. Remarkably, the best power conversion efficiency (PCE) of 14.40% for the dual bilayer planar solar cell is obtained, with a champion V OC of 656.4 mV. We provide an effective and facile strategy to design high efficiency with superior V OC by improving contact quality and passivation simultaneously in the Si-based solar cells.