Numerical optimization of CMTS thin-film solar cells via MoSe2 interfacial engineering

Copper manganese tin sulfide (Cu 2 MnSnS 4 , or CMTS) is emerging as a promising quaternary chalcogenide material for next-generation thin-film solar cells, owing to its abundance, tunable direct bandgap, and high optical absorption properties. In this study, we perform a comprehensive numerical analysis using the SCAPS-1D simulator to investigate and optimize the performance of CMTS-based solar cells, both with and without the inclusion of a MoSe 2 interfacial layer between the molybdenum (Mo) back contact and the absorber layer. Our findings highlight the crucial role of the p-type MoSe 2 interlayer in significantly enhancing the photovoltaic performance. With the MoSe 2 layer, the power conversion efficiency (PCE) of the device increased from 10.87% to 17.21%, achieving key photovoltaic parameters of open-circuit voltage (Voc) = 0.764 V, short-circuit current density (Jsc) = 30.03 mA/cm 2 , and a fill factor (FF) of 75% at an optimal doping level of ∼ 10 18 cm −3 . Further optimization of the device structure—ZnO:Al/SnS 2 /CMTS/MoSe 2 /Mo—was performed by varying key parameters such as absorber layer thickness, doping density, and energy bandgap of both the absorber and interfacial layers. The device performance was found to improve with an absorber thickness of 900 nm and a doping density of 10 19 cm −3 . The energy band alignment at the CMTS/MoSe 2 interface proved critical for performance, with the best efficiency achieved at a MoSe 2 bandgap of 1.25 eV, resulting in a peak efficiency of 25.98%. However, temperature effects were found to have a significant impact on device performance, with efficiency decreasing by approximately 25.85% as the operating temperature increased from 300 K to 500 K.