Modeling Cd-free buffer layer and defects analysis in CZTS solar cell

A compact numerical evaluation and optimization for CZTS (Cu2ZnSnS4) solar cell has been done using device simulation software. Various factors affecting the solar cell's performance has been rigorously investigated; more specifically physical parameters of buffer and absorber layer. By optimizing the device parameters we have achieved a simulated conversion efficiency of 15.6% with open circuit voltage (V-oc) = 0.8V, short circuit current density (J(sc)) = 26.4 mA/cm(2) and a fill factor (FF) = 79.7%. The role of defect density has been also studied to analyze the performance of cell module and comparative analysis with alternative buffer material (ZnIn2Se4) has also been discussed. The solar cell with an absorber layer's thickness of 2 pm, an acceptor concentration of 1x10(16) cm(-3) and buffer layer's thickness of 70nm was optimum. Compared to one of the best-reported values of conversion efficiency from CdS based CZTS films available in the literature, we have obtained improved performance parameters of the cell module. The optimization of device parameters outperforms most experimental devices by a large margin, indicating that there may possibly be huge potential for the improvement for conversion efficiency of CZTS solar cell.