Interlayer Coupling Prolonged Photogenerated Carrier Lifetime in Few Layered Bi2OS2 Semiconductors
Layered semiconductors with broad photoabsorption, long carrier lifetime and high carrier mobility are of crucial importance for high-performance optoelectronic and photovoltaic devices, whereas it is hard to satisfy these requirements simultaneously in a system due to the opposite dependence on layer thickness. Herein, by means of ab initio time-domain nonadiabatic molecular dynamic simulations, we find a new mechanism in Bi2OS2 nanosheet inducing an anomalous layer-dependent property of carrier lifetimes, which makes the few layered Bi2OS2 a possible system for fulfilling above requirements concurrently. It is revealed that the interlayer dipole-dipole interaction in few layered Bi2OS2 effectively breaks the two-fold degenerate orbitals of [BiS2] layers, which not only cuts down the overlap of the electron and hole wave functions, but also accelerates electron decoherence process. This significantly suppresses the electron-hole recombination and prolongs the photogenerated carrier lifetime in few layered Bi2OS2. The mechanism unveiled here paves a possible way for developing advanced optoelectronic and photovoltaic devices through engineering interlayer dipole-dipole coupling.