Review of nanostructured NiO thin film deposition using the spray pyrolysis technique

This study reviews NiO film deposition using the Spray Pyrolysis Technique (SPT). Physical and chemical methods can be used to deposit NiO film. This review looks at different precursors and their characterization methods for spray deposition of NiO thin film. The usefulness of SPT emanates from this method being simple, low cost, and viable for mass production. It gives high product purity for metallic and non-metallic material deposition. Nickel chloride, nickel acetate, nickel nitrate, nickel hydroxide, nickel sulfate, and nickel formate are the major precursors for NiO thin film deposition. Nickel chloride and nickel acetate are the most used and highly available precursors. Unlike nickel acetate, nickel chloride precursors corrode the deposition equipment (spray gun). These precursors are relatively cheap compared to current materials used for solar panels (cells). SPT equipment consumes negligible power during deposition and none after usage. Various authors have investigated the physical, chemical, optical, structural characterization and properties of nanostructured NiO thin film. NiO films are p-type semiconductors and as such possesses direct band gap suitable for various applications. The film has been categorized as an excellent material for optoelectronic applications because of its tune-ability for optimization. The wide band gap is in the range of 3.25-4.0 eV. This review will be useful to researchers exploring solar photovoltaic potentials for solving electricity problems of developing countries.