Enhanced the performance of CZTSSe solar cells by optimized i:ZnO window layer

We have systematically investigated the effect of i:ZnO window layer with different thickness on the performance of CZTSSe solar cells. The i:ZnO films were deposited on SLG substrate by adjusting the supttering time, and the accurate thickness was determined by XRR spectra. GIXRD, AFM images and absorption spectra show that the crystalline quality is stable and increases with the increase of thickness, while transmittivity declines. Furthermore, CZTSSe solar cells with the structure of SLG/Mo/CZTSSe/CdS/i:ZnO/ITO/Al were fabricated. It is found that Voc and FF of solar cell are affected by the thickness of i:ZnO layer obviously. The i:ZnO window layer plays an important role in reducing the channels of current leakage. Meanwhile, a compromise among the parallel conductance, series resistance and transmittivity are needed. By optimized the process, the efficiency of CZTSSe solar cell was significantly improved to 10.74 % when the thickness of i:ZnO was about 26 nm.