Structural, electronic, and optical properties of C3B and C3B0·5N0.5 monolayers: A many-body study

Abstract

Performing first-principles calculations, the structural, electronic, and optical properties of C 3 B and C 3 B 0·5 N 0.5 monolayers are investigated systematically. The calculations of cohesive energies, molecular dynamics, and phonon spectra show the energetic , thermal, and dynamical stabilities of C 3 B and C 3 B 0·5 N 0.5 monolayers. The C 3 B 0·5 N 0.5 (C 3 B) is predicted to be semiconductors with moderate direct (indirect) gap of 2.376 (1.948) eV at G 0 W 0 level. The observed systems both have good absorptions for the visible light . Compared with that of the C 3 B, first absorption peak of the C 3 B 0·5 N 0.5 is remarkably red-shifted, suggesting an enhanced absorption for the near-infrared light. The corresponding bright excitons have large binding energies, being 0.913 eV for the C 3 B and 0.704 eV for the C 3 B 0·5 N 0.5 , respectively. The relatively small binding energy of exciton in the C 3 B 0·5 N 0.5 is very beneficial for the separation of the photogenerated electron-hole pair. More importantly, the C 3 B 0·5 N 0.5 monolayer can achieve a large light absorption coefficient beyond 10 5 cm −1 for the sunlight irradiation. These findings enrich the deep understanding of C 3 B and C 3 B 0·5 N 0.5 monolayers, and indicate their potential applications in optoelectronics. Figure: Comparable optical absorptions of C 3 B and C 3 B 0·5 N 0.5 monolayers obtained by the G 0 W 0 +BSE method. • Electronic and optical properties of C 3 B and C 3 B 0·5 N 0.5 are investigated by the G 0 W 0 +BSE method. • The two compounds exhibits semiconducting properties with moderate indirect/direct bandgap. • Large exciton binding energies in two compounds show that these excitons have good stabilities against external force. • The two compounds have good optical properties that make them promising for optoelectronic applications.