CdInGaS4: An unexplored two- dimensional materials with desirable band gap for optoelectronic devices

The discovery of two-dimensional (2D) compounds with excellent optoelectronic properties have attracted much scientific attention. Based on first-principles calculations, we suggest a new 2D-CdInGaS4 nanocomposite monolayer and bilayer-whose layered bulk parent was synthesized in 1969. We show that the CdInGaS4 monolayer is dynamically, mechanically, and thermodynamically stable and has minimal cleavage energy similar to 0.275 J/m(2), which points out the feasibility of the exfoliation from lamellar bulk CdInGaS4 experimentally. The monolayer of CdInGaS4 with an indirect band gap of 1.497 eV at HSE06 functional is a semiconducting material. The indirect band gap of bi/tri-layers CdInGaS4 are estimated to be 1.420 and 1.297 eV, respectively indicating very weak quantum confinement effects in this system. It is noteworthy that the CdInGaS4 monolayer has a quasi-direct band gap of 1.50 eV at the Gamma-point, a slightly greater than the indirect band gap. The calculated electron mobility of CdInGaS4 monolayer is 700.55 cm(2) V-(1) S-1, which is comparable to or higher than that of 2D materials such as MoS2, MnPSe3, and Gel(2) mono-layers. Furthermore, 2D-v systems exhibit good absorption in the range of 1.6 eV-5 eV, which covering a wide wavelength range in the visible light region, and the corresponding optical absorption coefficients are in the magnitude of 10(5) cm(-1). The moderate band gap, electron mobility, and pronounced absorption coefficients indicate the proposed 2D-CdInGaS4 monolayer could be a promising candidate for application in optoelectronic devices. (C) 2020 Elsevier B.V. All rights reserved.