First-Principles Study of Group VA Monolayer Passivators for Perovskite Solar Cells

With the increasing energy demands, the production of high-performance perovskite solar cells at economic cost is favorable. However, there are limitations to their commercial applications due to defect formation and instability. Passivation technologies help support their desirable traits. Recently, experiments have proven nanoscale group VA monolayers to be good passivator candidates. Simulated by these recent results, we applied density functional theory to systematically investigate the structural, electronic, optical, and mechanical properties of α and β phases of group VA monolayers, including phosphorene, arsenene, antimonene, and bismuthene in this project. The theoretical results reveal the following: (1) α-phosphorene and β-arsenene have ideal valence band maximum locations, while all monolayers have ideal conduction band minimum locations for enhancing open-circuit potential; (2) most monolayers have light effective masses for improving short-circuit current densities; (3) the location of passivators is important due to their high absorption coefficients; and (4) α-arsenene, α-bismuthene, and α-antimonene are ductile, which can potentially be used in flexible solar cells. Overall, theoretical insights suggest that α-phosphorene and both α- and β-arsenene are promising passivators with the consideration of all the electronic, optical, and mechanical properties.