Metal tungstate as an electron transport layer: Diverse preparation methods and photovoltaic applications

Nanomaterials derived from metal tungstates featuring transition metals have emerged as a focal point in electrochemical research due to their abundant natural sources, cost-effectiveness, and environmentally friendly characteristics. This review examines the potential of metal tungstate (MWO_x) as an electron transport material (ETM) to enhance the performance of photovoltaic (PV) devices, proposing it as an alternative to traditional TiO₂-based ETMs. The first section explores various preparation methods, including wet chemical processes, solid-state synthesis, and bombardment techniques. The second section critically investigates recent advancements in utilizing MWO_x for high-performance PV devices, revealing its significant potential to replace conventional ETMs. The application of ultra-thin transition metal oxides (TMOs) in dye-sensitized, organic PV, and perovskite (PSK)-based solar cells is discussed in detail. We also highlight the rapidly expanding research interest in this topic over the past several years. Finally, we provide a perspective on the challenges and future directions in this field.