Enhanced Lifetime and Photostability with Low-Temperature Mesoporous ZnTiO₃/Compact SnO₂ Electrodes in Perovskite Solar Cells

Perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of 25 % mainly have SnO₂ or TiO₂ as electron-transporting layers (ETLs). Now, zinc titanate (ZnTiO₃, 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_0.05FA_0.81MA_0.14PbI_2.55B_r0.45 perovskite sandwiched between SnO₂-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.