Minimizing the Voltage Loss in Hole‐Conductor‐Free Printable Mesoscopic Perovskite Solar Cells

Abstract The hole‐conductor‐free printable mesoscopic perovskite solar cells based on the inorganic scaffolds of mesoporous titania, mesoporous zirconia, and porous carbon have attracted much attention due to their excellent stability and low manufacturing cost. However, in such hole‐conductor‐free devices, the transport of the photogenerated holes is dominated by the diffusion‐assisted charge carrier movement, while the driving force is insufficient. Reinforcing the built‐in electric field (BEF) is an effective strategy to promote oriented carrier transport. Herein, by using an optimized two‐step deposition method, the BEF is reinforced by creating a work function difference of perovskite (Δµ) in different layers via a gradient self‐doping. The enhanced BEF improves the hole transport and extraction, and significantly reduces the carrier recombination losses in the device. As a result, an average open‐circuit voltage improvement over 60 mV and a power conversion efficiency of 17.68% are achieved without any additives or complex processes. This strategy provides a new approach toward fabricating highly efficient printable mesoscopic perovskite solar cells with reduced carrier recombination losses.