Structural, mechanical and optoelectronic properties of B6X (X = Se, S) chalcogenides under hydrostatic pressure

Structural, mechanical and optoelectronic properties of B6Se and B6S chalcogenides under hydrostatic pressure were studied by the HSE06 hybrid functional in the DFT approach. The calculation results show that both materials preserve a high hardness behavior with a slight decrease of around 11% in the Vickers hardness, from zero to 100 GPa of external hydrostatic pressure. The electronic band structures show that B6Se and B6S chalcogenides have a semiconductor behavior with an electronic bandgap of 3.89 eV and 3.77 eV at zero GPa, respectively; decreasing 30% when 100 GPa of external pressure is applied. The optoelectronic properties evidence the possible modulation of the electronic band gap by the appliance of pressure as well as the refractive index in the visible region from n (?) = 2.8 to n (?) = 4.4 while the absorption coefficient suggest the potential applicability of both chalcogenides under extreme pressure conditions as UV sensors in an interval from 7.5 eV to 30 eV.