Progress in atomic layer deposition of metal oxides for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) are widely recognized as one of the most promising candidates for next-generation photovoltaics (PV), attributed to their outstanding power conversion efficiency and easily adjustable bandgap. Nevertheless, their practical commercialization remains challenging due to inherent material instabilities and rapid degradation triggered by exposure to moisture, oxygen, ultraviolet light, and thermal stress. In response, atomic layer deposition (ALD) has gained prominence as an advanced thin-film deposition technique, offering atomic-level precision and enabling the fabrication of uniform, conformal, and defect-minimized metal oxide (MO) layers. The ALD MOs serve versatile roles as charge transport layers, interfacial passivation coatings, and encapsulation barriers, collectively enhancing device performance, mechanical integrity, and operational durability. This review highlights the working mechanism of ALD, structural features of PSCs, and key strategies that leverage ALD-grown MOs to address efficiency loss and instability issues. Specific focus is given to defect passivation and protection against environmental factors. Moreover, challenges including precursor optimization, process compatibility with PSC architectures, and cost considerations are examined, along with future perspectives for industrial translation. Finally, the integration of ALD MOs holds strong potential to deliver the stability, efficiency, and scalability essential for the industrial application of PSCs in sustainable PV technologies.