A review of metal oxide semiconductors: Progress in solution-processed photovoltaic Technologies

Metal oxide semiconductors have emerged as a cornerstone in the development of solution-processed photovoltaic devices, driven by their unique physical and chemical properties. This review highlights the multifunctional roles of four key metal oxides-zinc oxide (ZnO), nickel oxide (NiO_X), tin oxide (SnO₂), and titanium oxide (TiO₂) in enhancing the performance and stability of organic and perovskite solar cells. These materials serve as electron and hole transport layers and demonstrate exceptional properties such as high carrier mobility, optical transparency, chemical stability, and tunable energy level. It also delves into strategies such as doping, interfacial engineering, and defect control to address challenges related to efficiency and stability. By analyzing practical examples, the review highlights how these optimization approaches drive breakthroughs in device efficiency, stability, and scalability. Through a comprehensive analysis of these metal oxides, this review underscores their critical role in achieving efficient, cost-effective, and scalable solution-processed photovoltaic technologies. Furthermore, it provides researchers with actionable technical insights and development strategies, fostering continuous advancements in renewable energy technologies and contributing to the global pursuit of sustainable energy solutions.