Computer Modeling Zinc Oxide/Silicon Heterojunction Solar Cells

Abstract

A new type of solar cells – Zinc Oxide/Silicon (ZnO/Si) hetero-junction are explored for their potentially low cost application. In order to find the optimal design structure of ZnO/p-Si solar cells, numerical modeling using SCAPS-1D (Solar Cell Capacitance Simulator One Dimension) is performed. We study the most important quality parameters, their variations and their impacts on performances of solar cells. The thickness of emitter and buffer layers is varied to observe its effect on the cell performance. Thus, the defects located in ZnO and Si layers, as well as, the role of the of interface defects’ density of the ZnO/c-Si heterojunction solar cells have been investigated in detail to provide guidelines for achieving high performance. The results indicate that the cell with an optimum thin buffer layer has higher performance. Also the output characteristics of these cells are significantly more sensitive to the defects in silicon surface than ZnO surface. The results also show that the interface defect states have an obvious effect on the open circuit voltage of these cells. We argue that the conversion efficiency of ZnO/c-Si heterojunction solar cells could be increased beyond 17 % by efficiently regulating interface Dit and defects in silicon layer.