Dual Bilayer for Improving Contact Quality and Passivation Enables Efficient Organic/Planar-Si Hybrid Solar Cells with a Champion V_OC of over 656 mV

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 (VOC). 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 (RS) 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 VOC of 656.4 mV. We provide an effective and facile strategy to design high efficiency with superior VOC by improving contact quality and passivation simultaneously in the Si-based solar cells.