Theoretical evaluation of emerging Cd-free Cu3BiS3 based solar cells using experimental data of chemically deposited Cu3BiS3 thin films

Highlights: • Cu₃BiS₃ films were obtained by thermal diffusion of chemically deposited Bi₂S₃/CuS stacks. • Single-phase Cu₃BiS₃ was confirmed by XRD and Raman spectroscopy. • Bi₂S₃ has been assessed as alternate buffer using SCAPS-1D. • Cu₃BiS₃/Bi₂S₃ heterostructure shows better performance than Cu₃BiS₃/CdS. • The improvement in efficiency is attributed to good band alignment. -- Abstract: The present research involves a combined experimental and theoretical study to evaluate the optoelectronic properties of Cu₃BiS₃ (CBS) semiconductor as an effective solar absorber in thin film photovoltaics. Our study consists of the synthesis and characterization of CBS films, followed by the execution of performance analysis as absorber material in a single heterojunction solar cell using numerical simulation by loading the individual material parameters for each layer of CBS solar cell into SCAPS-1D software. In the case of CBS layer, we considered the physical properties of CBS obtained experimentally in this work. The active layer was obtained by thermal diffusion of chemically deposited Bi₂S₃/CuS binary stacks at 300 °C and 350 °C in an inert atmosphere. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy studies confirm the appropriate composition as well as the formation of well-crystalline and single-phase orthorhombic Cu₃BiS₃ structure. Promising electrical properties were revealed by Hall effect measurements. The performance of the CBS layer was investigated considering the traditional CdS buffer layer and a Cd-free buffer layer such as Bi₂S₃. The higher conversion efficiency of 7.6% was obtained for CBS/Bi₂S₃ heterostructure compared with 6.8% efficiency using CdS buffer. A suitable band alignment at the CBS/Bi₂S₃ interface and ohmic back contact at Mo/CBS junction resulted to be mainly responsible for the enhanced efficiency.