Investigation of the potential of standalone and straddling-type sandwiched absorber solar cells with Sb2S3 and Sb2Se3 via DFT and SCAPS-1D simulation
摘要
Antimony chalcogenides (Sb2Se3 and Sb2S3) are increasingly recognized as promising absorber materials for thin-film solar cells owing to their strong optical response, natural abundance, and environmental compatibility. However, the device performance is still limited by an insufficient rear contact barrier, a high density of point defects in the bulk, a reduced carrier lifetime, and defect states at the interfaces. In this work, the Vienna Ab initio Simulation Package (VASP) is employed to investigate their structural and optoelectronic properties. Sb2Se3 and Sb2S3 exhibit direct band gaps of 1.17 eV and 1.62 eV, respectively, along with strong UV–visible absorption (~ 105 cm−1), confirming their suitability for efficient solar energy conversion. To leverage these properties, an optimized device architecture is proposed using SCAPS-1D, enabling simultaneous utilization of above- and sub-bandgap photons. The structure embeds a low-bandgap absorber within a high-bandgap matrix, forming a straddling-type heterostructure with favourable band alignment. This configuration is integrated with p+ and n+ layers to establish a strong internal electric field, which enhances carrier transport and suppresses recombination. Furthermore, different aspects of carrier transport within the confinement region are examined, along with key physical parameters—such as thickness, position, and barrier height—that govern overall device performance. The optimized configuration yields a theoretical power-conversion efficiency of ~ 35% under ideal conditions, exceeding conventional single-junction limits but serving as a simulation-based upper-bound prediction rather than an experimentally achieved value. The results provide a predictive roadmap for guiding future experimental optimization of stable, high-efficiency Sb-chalcogenide solar cells.