The Cu₂O thin film is a p-type oxide semiconductor and has a high absorption system and is environment-friendly and resource-friendly. Therefore, The Cu₂O thin film can be utilized in various fields of photoelectronic devices such as solar cell absorption layer, water splitting, or photo cathode material of photovoltaic cell. The Cu₂O thin film, which can be used as an optoelectronic device, is deposited by an electrochemical deposition process having advantageous features such as large-area deposition, precursor recycling, low-cost process, and low-temperature deposition. It is competitive both industrially and economically, which is a tremendous advantage. However, The Cu₂O thin films grown using atmospheric pressure and low-temperature based electrochemical deposition have lower conductivity than thin films grown using vacuum processes. Therefore, when a photocathode of a solar cell or an aqueous layer of a solar cell is fabricated, Electrons and holes can not move efficiently, and the efficiency of the device is inevitably lower than that of a thin film based on vacuum processing equipment. So as to solve the problem of conductivity of the thin film as described above, various methods such as optimization of the deposition method and application of the post-deposition process were carried out. In order to solve the existing problems, we have added Sb ion, which acts as a metal surface active agent, to maximize the preferential growth of the Cu₂O thin film and improve the preferential mobility of the thin film in [111] direction. This study deals with the process of optimizing the conductivity of Cu₂O thin film by controlling the molar concentration of Sb-ion. And We generated CuO on Cu₂O by a simple oxidation process, So effectively transporting the photogenerated charge in the Cu₂O photocell and transferring it to the electrolyte. The CuO as a heterojunction material enable to provide the additional built-in electric field is perfectly suitable band position. we fabricated to improve its photoelectrochemical (PEC) performance a Cu₂O/CuO interface with high crystallinity and a well-aligned atomic arrangement by preparing a Cu₂O absorber underlying layer preferentially oriented with [111] direction and forming a thin CuO overlayer (20–30 nm) via oxidation process at precisely controlled reduced oxygen partial pressure. This showed considerable enhancement in photocurrent density (2.8 mA/cm2 at 0 V vs. RHE) and onset potential (0.83 V), compared with those of initial Cu₂O. Highly, these enhancements were achieved without coating of photocatalytic materials on the photoelectrodes.