Controlled defects and enhanced electronic extraction in fluorine-incorporated zinc oxide for high-performance planar perovskite solar cells

Abstract

Oxygen-related defects in the intrinsic metal-oxide films restrict the transportation and collection processes of photogenerated carriers from the perovskite film to charge transport layers, which obstruct the applications of metal-oxide films in perovskite solar cells (PSCs). In this study, fluorine as an anion dopant was introduced to modify the oxygen-related defects in the intrinsic zinc oxide (ZnO). The impact of fluorine concentration on the structural, electrical, and optical characteristics of solution-processed ZnO films was systematically investigated. When the fluorine concentration was optimized to 15%, fluorine-doped ZnO (ZnO:F) film exhibited multiple advantageous effects, such as large crystalline size, low oxygen-related defect state density, good hydrophobic surface, and high conductivity. Furthermore, ZnO:F films with various fluorine concentrations as electron transport layers (ETLs) were introduced into the PSCs. The PSCs based on the ZnO:F ETL with the fluorine concentration of 15% yielded a maximum power conversion efficiency of 16.23% owing to the improvements of short-circuit current and fill factor. Meanwhile, the thermochemical stability of the device based on the ZnO:F ETL was also significantly improved.