Numerical Simulation of Ultrathin CdTe Solar Cell by SCAPS-1D

Abstract

Cadmium telluride (CdTe) has been recognized as one of the efficient and cost-effective thin film solar cell materials with a direct band energy of 1.5 eV. CdTe has long been a leading material in fabrication of solar cell due to its high optical absorption coefficient and ideal band gap. Despite the advantages of CdTe PV technology, CdTe is facing the challenge of Te scarcity. However, it is possible to decrease the CdTe thickness without much compromise in efficiency. Reducing the absorber layer thickness can lower the cost and usage of materials. It can assist to produce large scale CdTe solar cell module as Te is not an earth-abundant element. Numerical simulation of thin film solar cell is a crucial process for defining the possibility of anticipated solar structures, predicting the impact of differences in material characteristics and geometry on overall efficiency. In this research, Solar Cell Capacitance Simulator (SCAPS-1D) is applied to explore the impact of absorber layer thickness and carrier concentration in realizing ultrathin CdTe solar cell. It has been found that 500 nm thick absorber layer is sufficient for acceptable range of cell efficiency. Simulation results of 500 nm CdTe with the carrier concentration of 1.0 × 1014 cm−3 has an efficiency of 2.2%. For CdTe carrier concentration of 1.0 × 1017 cm−3, the efficiency increases to 13.22% with open-circuit voltage of 0.988 V, a short-circuit current density of 16.19 mA/cm2 and fill factor of 82.54%. The optimal numerical solar cell design suggests an approach to further enhance the efficiency of CdTe solar cells.