The optical properties and carrier mobility of MH3 (M = Co, Rh and Ir) monolayers

Abstract

A new series of two-dimensional transition metal hydrides MH₃ (M = Co, Rh, Ir) are investigated using first principles calculations. Their electronic structures, phonon dispersion, optical absorptions, and carrier mobilities are obtained and discussed. Our results on the basis of the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional reveal that CoH₃, RhH₃ and IrH₃ are indirect semiconductors with band gaps of 2.54 eV, 1.80 eV and 1.82 eV, respectively. Moreover, MH₃ monolayers show strong optical absorption in the visible and near-ultraviolet light regions. Under tensile strain, the band gaps decrease and the optical absorption is enhanced in the visible region. The obtained carrier mobilities are found to be anisotropic along the armchair and zigzag directions. The holes along the armchair are more easily transferred with high mobility. The strong optical absorption intensity and the relatively high carrier mobilities make MH₃ monolayers (especially RhH₃ and IrH₃) potential candidates for applications in photovoltaics.