Shift current photovoltaic efficiency of 2D materials

Shift current photovoltaic devices are potential candidates for future cheap, sustainable, and efficient electricity generation. In the present work, we calculate the solar-generated shift current and efficiencies in 326 different 2D materials obtained from the computational database C2DB. We apply, as metrics, the efficiencies of monolayer and multilayer samples. The monolayer efficiencies are generally found to be low, while the multilayer efficiencies of infinite stacks show great promise. Furthermore, the out-of-plane shift current response is considered, and material candidates for efficient out-of-plane shift current devices are identified. Among the screened materials, MXY Janus and MX₂ transition metal dichalchogenides (TMDs) constitute a prominent subset, with chromium based MXY Janus TMDs holding particular promise. Finally, in order to explain the band gap dependence of the PV efficiency, a simple gapped graphene model with a variable band gap is established and related to the calculated efficiencies.