Layered 2D semiconducting transition metal dichalcogenides for solar energy conversion

The attractive properties of the semiconducting transition metal dichalcogenides (TMDs) have inspired investigation into their suitability for solar energy conversion in the past decades. Only recently has their layered crystal structure been exploited via exfoliation methods to afford two-dimensional (2D) atomically thin sheets or flakes. These 2D TMDs have revealed enhanced light absorption properties and a high tolerance for heterojunction formation that has led to impressive photovoltaic device demonstrations with single or few layer TMD stacks. The devolvement of solution processing techniques to prepare multi-flake 2D TMD thin films with semiconducting behavior over large area gives promise to the possibility of inexpensive 2D TMD devices with robust performance for a number of solar energy conversion applications; however, understanding the roles of the edges states and defects to improve photogenerated charge harvesting remains a challenge.