Numerical analysis of CZTS thin film solar cells on Si substrate

• 1、School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006

Abstract：The Cu2ZnSnS4(CZTS) thin film solar cell prepared on Si substrate has the advantage of low lattice mismatch between CZTS absorber and Si substrate,but its conversion efficiency is still low at present. In this work, the CZTS thin film solar cells on Si substrate were calculated numerically by heterojunction solar cell simulation softwareAfors-het. The calculated results show that the p-CZTS and n-Si act as window layer and absorber respectively in the p-CZTS/n-Si solar cells. However, most of the incident lights cannot pass through the p-CZTS layer and then be absorbed by n-Si due to the high absorption coefficient of p-CZTS, which limits the conversion efficiency of p-CZTS/n-Si solar cell. A n-ZnO:Al/i-ZnO/n-CdS/p-CZTS/p-Si solar cell structure on p-Si substrate is proposed. The calculated darkcurrent density-voltage (J-V) characteristic curves of p-CZTS/p-Si structure are linear, indicating the formation of ohmic contact between p-CZTS and p-Si and the feasibility of p-Si as a back electrode of p-CZTS. The influences of the thicknesses and doping concentrations of p-Si and p-CZTS on the photovoltaic properties of n-ZnO:Al/i-ZnO/n-CdS/p-CZTS/p-Si solar cells were further calculated.The highest conversion efficiency of n-ZnO:Al/i-ZnO/n-CdS/p-CZTS/p-Si solar cell is 22.49%. The calculated results in this work show that the n-ZnO:Al/i-ZnO/n-CdS/p-CZTS/p-Si solar cell can solve the problems existing in the p-CZTS/n-Si structure and it is an appropriate structure for CZTS solar cell on Si substrate.

Keywords： CZTS Si Back electrode Photovoltaic property Afors-het software