First-principles study on the excellent photovoltaic, photocatalytic and photodetection performance of a new two-dimensional B₂C₆N₄ monolayer

Abstract This study conducts a systematic investigation into the strain-modulated electronic and optical properties of a novel two-dimensional (2D) boron-carbon-nitrogen (B 2 C 6 N 4 ) monolayer using first-principles calculations. The optimized BCN structure is characterized by an orthorhombic lattice and exhibits anisotropic mechanical properties. Phonon dispersion and ab initio molecular dynamics simulations confirm its dynamic and thermal stability under ambient conditions. The B 2 C 6 N 4 monolayer features an indirect bandgap of 1.31 eV, with valence and conduction band edges that straddle the water redox potentials, facilitating photocatalytic hydrogen evolution and oxygen production. Strain engineering, ranging from −3% to +3%, results in bidirectional modulation of the bandgap (1.18–1.46 eV), accompanied by shifts in band edge positions that align with the Shockley–Queisser optimal range for photovoltaic applications. Anisotropic carrier mobility is observed, with electron mobility exceeding 4815 cm 2 V −1 s −1 along specific crystallographic directions. Polarization-dependent optical absorption studies reveal strong responses in the visible-light and ultraviolet regions. These findings position the BCN monolayer as a promising candidate for flexible optoelectronics, adaptive photocatalysis, and strain-engineered solar cells.