Stability and electro-optical properties of the hydrogen-functionalized monolayer BC3H3: a theoretical study†

Abstract

Utilizing the PBE + G₀W₀ + BSE calculations from density-functional and many-body perturbation theories, we systematically investigate the stability and electro-optical properties of the hydrogen-functionalized monolayer BC₃H₃ across four configurations. BC₃H₃ monolayers with type-3 and type-4 configurations are verified to be stable dynamically and thermally. The type-3/type-4 configurations are predicted to be direct/indirect semiconductors with a moderate quasi-particle bandgap. Applied biaxial strain and an external electric field can both effectively tailor the bandgap over a broad range, even inducing a semiconductor–metal phase transition in both configurations. In particular, a biaxial tensile strain of +1.1% and a vertical electric field of ∼±0.05 V Å⁻¹ can cause an indirect-to-direct gap transition in the type-4 configuration. Moreover, the type-3 and type-4 configurations also show significant absorption coefficients for the near-ultraviolet light (larger than 10⁵ cm⁻¹) and large exciton binding energies. These results will be important for designing ultraviolet photoelectric devices based on the BC₃H₃ monolayer.