Analysis of the Efficiency of Sb2Se3 Thin-Film Solar Cells by Introducing Alternative Buffer Layers in n–p and n–i–p Structures by Numerical Simulation

Abstract Antimony selenide (Sb 2 Se 3 ) solar cells are a promising emerging thin-film photovoltaic technology, but their record experimental efficiency (10.57%) remains well below the theoretical limit of ~30%. This research demonstrates, by numerical simulation, that using different buffer or electron transport layers (ETL) and device structures ( n – p or n −i− p ) can significantly reduce the open-circuit voltage (V oc ) deficit and improve solar cell performance. We restrict the analysis to realistic material parameters, moderate defect densities, and exclusively inorganic ETLs and hole transport layers (HTLs), to facilitate experimental implementation. In n – p structures, we compare CdS with alternative single ETLs (CdSe, ZnO, V 2 O 5 ) and bilayers (CdS/CdSe and ZnO/V 2 O 5 ), explicitly analyzing band alignment, lattice mismatch, and interface defect density. V 2 O 5 is a promising ETL owing to its favorable band offset and small lattice mismatch with Sb 2 Se 3 . By introducing a Cu 2 O HTL to form an n –i– p structure, we demonstrate that the internal electric field distribution can be tailored to suppress bulk recombination in the absorber, resulting in V oc > 600 mV and efficiencies up to 17% after thickness optimization. The results provide practical design rules for integrating inorganic ETLs and HTLs in Sb 2 Se 3 solar cells, and highlight device architectures that can realistically push efficiencies beyond the current experimental record.