Extensive Study on Effects of Defects in CZTS/CZTSe Quantum Dots Kesterite Solar Cells

Earth abundant Kesterite semiconductor is emerging as a promising solar cell candidate due to it's low-cost, environment friendly and non-toxic absorber nature with suitable optical properties. However, the achievable conversion efficiency is quite low because of high defect density, interface traps and grain boundaries. In this study a numerical simulator is used to understand the effects of each point of GB defects on the electrical characteristics of kesterite solar cells step-by-step. An overview of all limiting factors such as GB defects, deep defects and tail states associated with recombination mechanisms are presented with help of exponential tail distribution and Gaussian distributions. The ideal QD embedded kesterite solar cell shows an efficiency of 41.4%, while it reduces to 15.6% after considering all of the above mentioned defects in barrier (CZTS) and QD (CZTSSe) material. The distribution of defects inside the band gap is shown here with the help of density of states by using exponential tail distribution and Gaussian distributions functions.