A Comprehensive Simulation Study of CdTe Energy Gap Effects on CdTe/CdS Solar Cell Characteristics: SCAPS-1D

Abstract

The energy gap of the CdTe absorber layer in CdTe/CdS solar cells has a dominant effect on their performance. In this work, the effects of altering the energy band gap of CdTe (1.37 eV; 1.47 eV; 1.54 eV) on the features of the solar cell were analyzed using SCAPS-1D program. From our results, CdTe energy gap was found to be directly proportional to the open-circuit voltage (Voc), meaning that higher energy gaps gave higher Voc. But this was compensated by a fall in the short circuit current density (Jsc) due to light capture reduction effect which also contributes to the powering up of the cell. An appropriate energy bandgap of 1.47 eV for the CdTe layer has been calculated to secure high values of Voc and quite a high Jsc to increase overall conversion efficiency of the solar cell. Moreover, a noticeable trend appears in capacitance and conductance whereby smaller energy gaps yielded higher capacitance and conductance. The quantum efficiency was also changed; lower energy gaps had a better ability to absorb the photons and have higher efficiency to varying ranges of wavelengths. This study underscores the critical role of accurately tuning the CdTe energy gap during fabrication to optimize the efficiency of CdTe/CdS solar cells.