Strongly anisotropic optoelectronic properties and long exciton lifetimes in two-dimensional GaInS3-type monolayers.

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Citation 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 constructed non-centrosymmetric GalnS 3 -like monolayers, 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 photon-generated carriers. Importantly, the three ABM 3 monolayers exhibit larger exciton binding energy with a BSE optical band gap in the visible light range, and their exciton lifetime is up to 7.05 ps for β-GaInS 3 at 0 K. In addition, these three structures exhibit highly anisotropic electron mobilities (up to ∼10 3 cm 2 V -1 s -1 ) due to their larger lattice anisotropy.