Achieving uniform elemental distribution and high crystallinity in Cu3V(S,Se)4 solar cells via optimizing selenization engineering

The selenization parameters for solution-based Cu3V(S,Se)4 thin film solar cells were systematically studied. An increasing selenization temperature can help Cu, S, and Se elements diffuse effectively, distribute evenly in the crystal grains and grain boundaries, which improve the crystallinity, compactness, and electrical properties of the Cu3V(S,Se)4 films. The extension of selenization time can also optimize the crystallinity of the film. The optimal selenization parameters are determined to be 530 °C and 70 min, and the corresponding thin film is also regarded as the best sample. The band structure of the best sample is studied further and matches that of the buffer layer. Finally, the assembled device can present the best photoelectric conversion efficiency (PCE) of 2.16%, which is increased by 28.6% compared with what we previously reported in 2024 (1.68%).