Elucidating the Potential Strategies for Performance Improvement of CBTSSe‐Based Solar Cells: A Pathway Toward 20% Efficiency

Cu2BaSnS4−xSex (CBTSSe) has recently attracted substantial attention as an emerging chalcogenide material due to its abundant constituent elements and reduced antisite disorders compared to the Cu2ZnSn(S,Se)4 (CZTSSe). In this work, recently reported Mo/CBTSSe/Cd:ZnS Zn1−xCdxS/i‐Mg:ZnO (ZMO)/Al:ZnO (AZO) cell structure with the power conversion efficiency (PCE) of 6.17% is used to develop the baseline model. Afterwards, device performance parameters are fine‐tuned by investigating the effect of (a) absorber thickness and defect density, (b) absorber/buffer conduction band offset, (c) absorber/buffer interface defect density, (d) anti‐reflection coating at the front layer, and (e) back contact optimization. The device with the optimized parameter values of absorber thickness: 1.2 μm, absorber defect density: 1015 cm−3, and alternate buffer layer of WS2, interface defect density:1010 cm−2, resulting in the PCE of 12.94%. Introducing an anti‐reflective coating (ARC) at the front contact further improves the PCE to 17.87%. Finally, introducing Ni as a back contact instead of Mo enhances the PCE to 20.70%. These results provide insight into possible techniques to improve the performance of CBTSSe‐based solar cells. The earth‐abundant multinary chalcogenide, Cu2BaSn(S,Se)4, is an emerging choice as an absorber for photovoltaic applications. This research article presents a systematic approach to optimize the various layers of the cell. By appropriate substitution of the buffer layer and the back metal contact, a proposed device achieves an efficiency of 20.70%.