Enhanced performance of thin-film amorphous silicon (a-Si) solar cells encapsulated with distributed Bragg reflector pairs

Thin-film photovoltaic cells are attracting increasing attention due to their remarkable properties of thin size and low cost. However, to enable the wider use of solar cells to replace conventional carbon-based methods of electricity production, the low performance parameters in thin films need to be improved. In this study, amorphous silicon (a-Si) is used as an active layer, for which the optimization of the back surface field (BSF) layer is performed. Different materials for BSF, including gallium arsenide (GaAs), zinc telluride (ZnTe), and zinc selenium (ZnSe), are tested, and ZnSe appears to be more efficient than GaAs and ZnTe. Moreover, to capture photons in the active region more efficiently, a distributed Bragg reflector (DBR) is utilized, which is composed of silicon/silicon nitride (Si/SiN). The encapsulated DBR pair appears to be beneficial for the proposed design and provides excellent electrical parameters as compared to a structure without DBR. Under Standard Test Conditions (STC) at 300 K, the structure delivers Voc = 0.832 V, Jsc = 14.68 mA/cm2, FF = 76.53%, and η = 9.34%. The present study also highlights thermal stability analysis of the proposed structure at different temperatures, and the results show that as the temperature of the device increases, the performance of the cell follows a downtrend toward decay.