The diode and photovoltaic properties of spray-deposited ITO/n-Si solar cells are very similar to those of SnO2/n-Si devices. These cells have relatively high conversion efficiencies of 11∼13%. The cell performances are affected by the work functions (or electron affinities) of ITO and SnO2 films, and by the interface states. The work functions (or electron affinities) and band gaps of ITO and SnO2 films vary by the preparation techniques. Spray-deposited ITO/n-Si and SnO2/n-Si solar cells do not operate at minority-carrier diodes.