Unraveling the interfacial electronic structure and carrier dynamics engineered by the MoSe2 layer in Sb2Se3 solar cells: A numerical physics perspective

The performance of Sb 2 Se 3 solar cells is profoundly influenced by the MoSe 2 interfacial layer (IL), yet the underlying physics governing its function require clarification. Through detailed numerical simulation, we decipher its operation through three core mechanisms. The IL serves first as an interfacial dipole modulator, reconstituting band bending to lower the hole Schottky barrier by 38.4 meV and establishing thermionic-field emission as the dominant transport pathway. It secondly acts as a bulk defect passivator, drastically reducing the Urbach energy from 39.2 meV to 22.3 meV to suppress Shockley-Read-Hall recombination within the absorber. Thirdly, the resulting improvement in bulk material quality indirectly enhances the front CdS/Sb 2 Se 3 heterojunction. By linking these interconnected roles, namely barrier engineering, defect suppression, and junction improvement, this study provides a foundational and generalizable physics framework for interfacial design in chalcogenide photovoltaics. • The p-MoSe 2 layer tunes back-contact energetics, passivates defects, and enhances the heterojunction. • A reduced Schottky barrier switches transport to thermionic-field emission, cutting series resistance by 43%. • A 43.5% drop in Urbach energy confirms deep-level passivation, suppressing Shockley-Read-Hall recombination. • Enhanced Sb 2 Se 3 bulk properties reduce interface states at the CdS/Sb 2 Se 3 junction, raising recombination activation energy. • This study provides a foundational blueprint for interlayer design in chalcogenide photovoltaics beyond empirical optimization.