Highly stable inverted perovskite solar cells with all-inorganic selective contact using iron-doped zinc oxide

Perovskite solar cells (PSCs) have achieved remarkable performance advancements over the past decade. In inverted p-i-n PSCs, commonly utilized electron transport layers (ETL), such as C60 and PCBM, are associated with notable stability challenges and high production costs. This study reports on a novel and highly stable perovskite solar cell that employs iron-doped zinc oxide (FZO) nanoparticles as the ETL and nickel oxide (NiOx) as the hole transport layer, demonstrating a power conversion efficiency (PCE) of ∼12%. In comparison with PSCs that utilize zinc oxide (ZnO) as the ETL, those incorporating FZO demonstrated a maximum PCE enhancement of 18.3%. The incorporation of iron doping mitigates the basicity of the ZnO ETL, thereby reducing the deprotonation at the FZO/perovskite interface and enhancing the stability of the PSCs. The unpackaged FZO device maintained an initial PCE of 90% after 400 h at a relative humidity of 45% ± 5%. (2-(9H-carbazol-9-yl)ethyl)phosphonic acid and 2-phenylethylamine hydroiodide were used to passivate the NiOx/perovskite and perovskite/ZnO(FZO) interfaces, respectively, which further improved the PSC performance. Ultimately, FZO-based PSCs with a PCE of 13.65%, an open-circuit voltage (Voc) of 1.04 V, a short-circuit current density (Jsc) of 20.79, and a fill factor (FF) of 63.1% were obtained, and the PCE demonstrated a notable increase of over 35% compared to pristine ZnO-based devices. Results indicate that high device performance, low fabrication costs, and excellent stability can be attained through the use of simple chemically synthesized oxides as inorganic selective charge transport layers in PSCs.