An all-transparent photodetector was fabricated by structuring Cu₂O/ZnO/AZO/ITO on a glass substrate. The visible-range transmittance was as high as 80%, which ensures clear vision forhuman eyes. High-transparency metal conductive oxides (p-type Cu₂O and n-type ZnO) were appliedto form the transparent p/n junction. The functional AZO layer was adopted to improve the transparent photodetector performance between the ZnO and ITO, improving the photoresponses because of its electrical conductivity. To clarify the AZO functionality, a comparator device was prepared without the AZO layer in the formation of Cu₂O/ZnO/ITO/Glass. The Cu₂O/ZnO/AZO/ITO device provided a rectifying ratio of 113.46, significantly better than the 9.44 of the Cu₂O/ZnO/ITO device. In addition, the Cu₂O/ZnO/AZO/ITO device`s photoresponses at short wavelengths were better than those of the comparator. The functioning AZO layer provides ahigh-performing transparent Cu oxide photodetector and may suggest a route for the design of efficient photoelectric devices.