The Study on Photoelectric Response Properties of CIGS Film With V-Shaped Bandgap Regulated by Adjustment of Cu and Se Concentrations

In this study, a V-shaped bandgap structure was constructed by regulating the gradient of Cu and Se in CIGS, which confirmed the experimental feasibility of controlling the band structure of Cu and Se and provided a new idea for regulating the energy band structure of CIGS. The V-shaped bandgap CIGS thin film was fabricated by layered sputtering with variable targets. The results show that the V-bandgap CIGS films have better crystallinity and electrical properties, resulting from the synergistic effect of the Cu gradient and Se gradient. The photoresponse current curve shows that V-shaped bandgap film has good photosensitivity; the maximum photogenerated current can reach 317.5 mA. The photocarrier ratio of CIGS films with a V-band gap is considerably higher than that of single-band gap films, reaching a value of 34.1%. The photoelectric response current curve analysis results show that the V-shaped bandgap CIGS films prepared by adjusting the concentration of Cu and Se have stronger photogenerated carrier generation ability and better photophase response performance. This work provides a new preparation method for large-area and high-efficiency preparation of CIGS films with excellent performance, and promotes the further development and application in thin film solar cells and photodetectors.