Effects of temperature-time profile on Cu2ZnSnS4 films and cells based on sulfur-contained precursors

Cu2ZnSnS4 (CZTS) films with high-quality are necessary to the high-performance CZTS solar cells. The influence of different temperature-time profiles during sulfurization on CZTS films were investigated by characterizing the compactness, roughness and grain size of CZTS films. With slowing the heating-rate during sulfurization process, the grain size of the film is becoming larger and larger, but the large grain size degrades the flatness of the CZTS films at the same time. The formation of films having the target composition (EDX) and phase purity (Raman) was attributed to the optimum choice of composition ration of the precursor and the thermal profile during sulfurization. The optical and electrical properties of corresponding CZTS films were detected by using UV-vis-INR Spectrophotometer and Hall measurement, respectively. Finally, the CZTS film solar cells were fabricated and the best cell demonstrated 3.91% efficiency. A high Rs is the main reason to inhibit the performance of the cells.