Two-Dimensional MGeSe: Promising Photovoltaic Materials with Long Carrier Lifetime and High Photocurrent

Two-dimensional (2D) group III-IV-VI semiconductors show great potential for application in energy conversion fields. Herein, using density functional theory (DFT) calculations in conjunction with nonadiabatic molecular dynamics (NAMD) simulations and the nonequilibrium Green's function (NEGF) method, the photovoltaic performance of MGeSe (M = Ga and In) monolayers is systematically investigated. The MGeSe monolayers exhibit direct band gap semiconductor characteristics with strong optical absorption in the visible light region. Notably, the exciton binding energies and carrier lifetimes of GaGeSe (InGeSe) are 0.49 eV (0.50 eV) and 0.20 ns (2.82 ns), respectively, indicating efficient exciton dissociation and charge transport. Moreover, the maximum photocurrent and photoresponsivity of InGeSe reach 19.4 A/m2 and 0.39 A/W, highlighting its potential for high-efficiency photovoltaic applications. These findings provide valuable insights into the photovoltaic behavior of MGeSe monolayers and offer theoretical guidance for the design of next-generation 2D photovoltaic materials.