Phosphorene and Transition Metal Dichalcogenide 2D Heterojunctions: Application in Excitonic Solar Cells

Using the first-principles GW-Bethe-Salpeter equation method, here we study the excited-state properties, including quasi-particle band structures and optical spectra, of phosphorene, a two-dimensional (2D) atomic layer of black phosphorus. The quasi-particle band gap of monolayer phosphorene is 2.15 eV and its optical gap is 1.6 eV, which is suitable for excitonic thin film solar cell applications. Next, this potential application is analysed by considering type-II heterostructures with single layered phosphorene and transition metal dichalcogenides (TMDs). These heterojunctions have a potential maximum power conversion efficiency of up to 12\%, which can be further enhanced to 20\% by strain engineering. Our results show that phosphorene is not only a promising new material for use in nanoscale electronics, but also in optoelectronics.