Surface Lattice Perturbation of Electron Transport Layer Reducing Oxygen Vacancies for Positive Photovoltaic Effect

For carbon‐based fully printable mesoscopic perovskite solar cells (FP‐PSCs), due to the serious interfacial defects formed in the uncontrollable crystallization process, modifying the interface between perovskite and electron transport layer is an effective way to enhance their photovoltaic performance. Herein, ultrathin ZrO 2 is deposited on the mesoporous TiO 2 surface by using spray pyrolysis, and Zr 4+ intercalates into the TiO 2 surface lattice and works together with Ti 4+ and O 2− ions. Thanks to this surface lattice perturbation of Zr 4+ , the reduction of surface oxygen vacancies of TiO 2 (electron transport layer) decreases the density of defective states at the TiO 2 –perovskite interface inhibiting the Shockley–Read–Hall recombination (nonradiative recombination) in the charge cross‐interface transfer. Furthermore, both the open‐circuit voltage and short‐circuit current density are improved significantly. Based on perovskite Cs 0.05 (FA 0.92 MA 0.08 ) 0.95 Pb(I 0.92 Br 0.08 ) 3 for carbon‐based FP‐PSCs, a high power conversion efficiency of 17.81% is obtained. It provides a novel idea and technology for efficient interfacial modification of the electron transport layer for FP‐PSCs.