Novel Janus diamane C4FCl: a stable and moderate bandgap semiconductor with a huge excitonic effect

摘要

Semiconducting two-dimensional Janus materials have drawn increasing attention due to their novel optoelectronic properties. Here, employing first-principles calculations, we systematically explore the stability and electronic and optical properties of Janus diamane C4FCl. The energetic and dynamical stabilities of C4FCl have been verified using the cohesive energy and phonon dispersion calculations. It is predicted to possess a direct bandgap of similar to 3 eV at the Gamma point using the G(0)W(0) method. Also, the optical absorption spectrum of C4FCl is dominated by the enhanced excitonic effects, in which a bright bound exciton with a large binding energy beyond 1 eV can be observed. The light absorption coefficient of C4FCl for sunlight can be as large as 8 x 10(4) cm(-1) in the range of visible and near-ultraviolet light, suggesting its potential for optoelectronic applications. These findings enable a deep understanding of the physical properties of novel C4FCl.