Substrate Interface Engineering for Drastically Boosted Short-Circuit Current Density and Fill Factor in Perovskite Solar Cells

Unlike the widely studied upper interface [interface between the hole transport layer and perovskite in n–i–p perovskite solar cells (PSCs)] which only transports carriers, the substrate interface (interface between the electron transport layer and the transparent conductive substrate) transports charge carriers and photons simultaneously. Therefore, managing this interface is crucial for manufacturing high-efficiency PSCs, while it remained largely unexplored previously. Herein, we constructed micro-/nano-antireflection structures and decreased the photon transmission distance to reduce photon loss through substrate interface engineering. In addition, energy level alignment was found to be more matched at the substrate interface to improve the carrier extraction after substrate treatment. Consequently, this tailored substrate interface enabled significantly improved photovoltaic performance of PSCs with a power conversion efficiency (PCE) of up to 24.47%, due to the dramatically enhanced short-circuit current density (JSC) from 24.95 to 25.79 mA·cm–2 and fill factor (FF) from 81.59 to 83.22%. This work profoundly uncovered vital scientific importance hidden in the substrate interface for affecting the JSC and FF, opening up research insight for designing enhanced light management and interface electron transport through substrate interface engineering for higher efficiency metal halide perovskite photovoltaics.