Impact of high resistivity transparent (HRT) layer in cadmium telluride solar cells from numerical simulation

In this study, Solar Cell Capacitance Simulator (SCAPS-1D) is utilized to examine the properties of cadmium telluride (CdTe) based solar cell. The key aim of this study is to explore the prospects of enhancing the efficiency of CdTe solar cells by adding a high resistivity transparent (HRT) layer to the conventional cell structure. For that purpose, novel HRT layer structures are suggested in CdTe solar cells between a cadmium sulfide (CdS) window layer and transparent conductive oxide (TCO) layer. Simulation results presented in this paper are from four proposed structures with three different HRT materials compared to the conventional design. The optimal parameters that offer the optimum functionality of the conventional design (SnO2/CdS/CdTe/MoTe2), with and without the HRT layer, are determined. Obtained results validate an enhancement in efficiency of the solar cell with Zn2SO4 as the HRT layer due to lower recombination loss and barrier height at the back contact region. The suggested cell with Zn2SO4 demonstrates an efficiency of 17.61% (Voc = 0.92 V, Jsc = 25.41 mA/cm(2), FF = 75.35), with only 20 nm HRT layer and 25 nm CdS as a window layer. In the meantime, the reference cell (no HRT layer) depicts an efficiency of 17.01% with 4000 nm thick CdTe as an absorber layer. However, the normalized efficiency of the suggested cells decreases linearly with increased temperature.