Preparation of submicron-sized cuprous oxide crystallites by electrodeposition with polyethylene glycol as additive

► Submicron-sized Cu2O crystallites is electrodeposited on ITO. ► The dispersity of crystallites is greatly improved by adding PEG as the additive. ► The mechanism in the growth of submicron-sized Cu2O crystallites is discussed. ► The band gap width of submicron-sized Cu2O crystallite is approximately 2.17 eV. ► The photoelectric property of Cu2O crystallites deposited with PEG is better.