Band-edge engineering via molecule intercalation: a new strategy to improve stability of few-layer black phosphorus

The poor environmental stability of black phosphorous (BP) seriously limits its practical applications in (opto)electronics. Other than capping protective layers on its surface, herein we propose a new strategy to improve BP's ambient stability by engineering the interlayer interactions. Our first-principles calculations demonstrate that enlarging the interlayer spacing can effectively shift the conduction band minimum down to suppress the generation of superoxide and the enlargement can be achieved by intercalating small molecules like H₂ and He into BP. Moreover, the molecule intercalated BP maintains high hole mobility, which makes it a better two-dimensional semiconductor for practical applications.