Atomic Layer Engineering of Aluminum‐Doped Zinc Oxide Films for Efficient and Stable Perovskite Solar Cells

Atomic layer deposition (ALD) has been considered as an efficient method to deposit high quality and uniform thin films of various electron transport materials for perovskite solar cells (PSCs). Here, the effect of deposition sequence in the ALD process of aluminum‐doped zinc oxide (AZO) films on the performance and stability of PSCs is investigated. Particularly, the surface of AZO film is terminated by diethylzinc (DEZ)/H2O (AZO‐1) or trimethylaluminum (TMA)/H2O pulse (AZO‐2), and investigated with surface‐sensitive X‐ray photoelectron spectroscopy technique. It is observed that AZO‐2 significantly enhances the thermal stability of the upcoming methylammonium lead iodide (MAPbI3) layer and facilitates charge transport at the interface as evidenced by photoluminescence spectroscopes and favorable interfacial band alignment. Finally, planar‐type PSC with AZO‐2 layer exhibits a champion power conversion efficiency of 18.09% with negligible hysteresis and retains 82% of the initial efficiency after aging for 100 h under ambient conditions (relative humidity 40 ± 5%). These results highlight the importance of atomic layer engineering for developing efficient and stable PSCs. This article reports the modification of atomic layer deposition sequence during the formation of aluminum‐doped zinc oxide (AZO) films. This process affects the optoelectronic properties of the upcoming perovskite film and its stability after exposure to high temperature. In addition, the performance and stability after prolong exposure to ambient conditions of the AZO‐modified perovskite solar cells is improved.