Towards High-Efficiency CZTSe Solar Cells Through the Optimization of the p-MoSe2 Interfacial Layer

This paper reports the impact of the p-MoSe2 transition metal dichalcogenide as an interfacial layer between the CZTSe absorber and Mo back contact in the CZTSe solar cells. Here, the solar cell capacitance simulator (SCAPS-1D) is employed. The I-V characteristic demonstrated a higher slope in comparison to CZTSe solar cell without considering the interfacial layer. The results show that the p-MoSe2 layer benefits the CZTSe/Mo hetero contact by mediating the quasi- ohmic back contact of the CZTSe solar cell. Accordingly, the conversion efficiency improves from 16.17 % to 23.47 %. To investigate the effect of the p-MoSe2 layer, various performance parameters such as open-circuit voltage (Voc), short circuit current (Jsc), fill factor FF, and efficiency t]were explored at a wide range of thicknesses, bandgap energies, and the carrier concentration. The results revealed that a thickness of the interfacial layer less than 70 nm would cause deterioration of overall cell performance. This is because a low thickness of p-MoSe2 creates high barriers at the CZTS/p-MoSe2 and p-MoSe2/Mo interfaces, which impedes the drift process of photogenerated holes. Additionally, increasing the acceptor carrier concentration doping (NA) above 1017 cm3 results in an improved cell performance due to the enhanced band alignment at the back contact. The obtained values of the Voc and Jsc are 0.74 V and 42.6 mA/cm2, respectively.