UV‐Inert ZnTiO3 Electron Selective Layer for Photostable Perovskite Solar Cells

Abstract Although planar‐structured perovskite solar cells (PSCs) have power conversion efficiencies exceeding 24%, the poor photostability, especially with ultraviolet irradiance (UV) severely limits commercial application. The most commonly‐used TiO 2 electron selective layer has a strong photocatalytic effect on perovskite/TiO 2 interface when TiO 2 is excited by UV light. Here a UV‐inert ZnTiO 3 is reported as the electron selective layer in planar PSCs. ZnTiO 3 is a perovskite‐structured semiconductor with excellent chemical stability and poor photocatalysis. Solar cells are fabricated with a structure of indium doped tin oxide (ITO)/ZnTiO 3 /Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 /Sprio‐MeOTAD/Au. The champion device exhibits a stabilized power conversion efficiency of 19.8% with improved photostability. The device holds 90% of its initial efficiency after 100 h of UV soaking (365 nm, 8 mW cm −2 ), compared with 55% for TiO 2 ‐based devices. This work provides a new class of electron selective materials with excellent UV stability in perovskite solar cell applications.