Enhanced Lifetime and Photostability with Low‐Temperature Mesoporous ZnTiO 3 /Compact SnO 2 Electrodes in Perovskite Solar Cells

Perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of 25 % mainly have SnO 2 or TiO 2 as electron‐transporting layers (ETLs). Now, zinc titanate (ZnTiO 3 , ZTO) is proposed as mesoporous ETLs owing to its weak photo‐effect, excellent carrier extraction, and transfer properties. Uniform mesoporous films were obtained by spinning coating the ZTO ink and annealed below 150 °C. Photovoltaic devices based on Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 B r0.45 perovskite sandwiched between SnO 2 ‐mesorporous ZTO electrode and Spiro‐OMeTAD layer achieved the PCE of 20.5 %. The PSCs retained more than 95 % of their original efficiency after 100 days lifetime test without being encapsulated. Additionally, the PSCs retained over 95 % of the initial performance when subjected at the maximum power point voltage for 120 h under AM 1.5 G illumination (100 mW cm −2 ), demonstrating superior working stability. The application of ZTO provides a better choice for ETLs of PSCs.