Deposition conditions of cuprous oxide (Cu2O) thin films on glass substrates and nitrogen doping into Cu2O were studiedby using reactive radio-frequency magnetron sputtering method. The effects of defect passivation by crown-ether cyanidetreatment, which simply involves immersion in KCN solutions containing 18-crown-6 followed by rinse, were alsostudied. By the crown-ether cyanide treatment, the luminescence intensity due to the near-band-edge emission of Cu2Oat around 680 nm was enhanced, and the hole density was increased from 1016 to 1017 cm3. Finally, polycrystalline p-Cu2O/n-ZnO heterojunctions were grown for use in solar cells. Two deposition sequences were studied, ZnO depositedon Cu2O and Cu2O deposited on ZnO. It was found that the crystallographic orientation and current–voltage characteristicsof the heterojunction were significantly influenced by the deposition sequence, both being far superior for the heterojunctionwith structure Cu2O on ZnO than for the inverse structure. We successfully obtained a photoresponse for the firsttime in the deposited thin film of Cu2O/ZnO.