A new two-dimensional MgICl Janus monolayer for optoelectronic applications

Using first-principles calculations based on density functional theory (DFT), the structural, optoelectronic, and transport properties of the MgICl Janus monolayer have been investigated. The stability is validated by the ab-initio molecular dynamics (AIMD), cohesive energy, and phonon spectrum. We found that Janus MgICl monolayer is a direct band-gap semiconductor with an energy gap of 3.35 eV (PBE) and 4.87 eV (HSE), and is energetic and dynamically stable. The dielectric matrix has been calculated within the random phase approximation (RPA). The optical-absorption coefficient is found to be very less in the visible region, and the calculated refractive index values are very near to that of water. The reflectivity is found to be less than 10% in the visible region which further increases in the UV region. The electrical conductivity of the Janus MgICl using Boltzmann transport theory, and the effective mass of electrons and holes have been calculated; the results present good electrical conductivity and small values of effective mass owing to high mobility. These theoretical investigations suggest that the Janus MgICl is a thermodynamically stable and promising material for use in the solar cells as a transparent conductor material. Graphical Abstract