Strongly Anisotropic Optoelectronic Properties and Long Exciton Lifetimes in Two-Dimensional GaInS 3 -Type Monolayers

Abstract

Two-dimensional (2D) layered GalnS 3 materials have attracted huge attention due to their excellent anisotropic photoelectric properties for photovoltaic devices.However, the monolayer α-GaInS 3 possesses an indirect band gap, which significantly limits its practical applications. Therefore, we construct a non-centrosymmetric GalnS 3 -like monolayer, namely, ABM 3 (A=Ga, In, Al; B=Ga, In, Al; M=S, Se, Te), and investigated their electronic and excitonic properties using high-precision G 0 W 0 -BSE methods. Our results indicated that β-GaInS 3 , GaAlSe 3 , and AlInSe 3 monolayers possess direct band gaps with desirable structural stability. Moreover, the built-in electric potential differences of these non-centrosymmetric monolayers can promote the separation of the photon-generated carrier. Importantly, the three ABM 3 monolayers exhibit larger exciton binding energy with a BSE optical band gap range of visible light, and their exciton lifetime is up to 7.05 ps for β-GaInS 3 at 0 K. In addition, these three structures exhibit outstandingly anisotropic electron mobilities (up to ~10³ cm² V⁻¹ s⁻¹) due to their larger lattice anisotropy.