Highly efficient photogenerated electron transfer at a black phosphorus/indium selenide heterostructure interface from ultrafast dynamics

Constructing van der Waals (vdW) semiconductor heterostructures is a possible approach to optimize the optoelectronic properties, and understanding photogenerated charge carrier dynamics at vdW heterostructure interfaces is of crucial importance. By using time-dependent ab initio nonadiabatic molecular dynamics simulations, we study the dynamics of photogenerated electrons at a BP/InSe heterostructure interface and observethe highly efficient separation of photogenerated electron-hole pairs at the interface. Instead of direct tunneling, the ultrafast transfer of excited electrons is significantly promoted by an adiabatic mechanism related to thermally excited nuclear motions stemming from strong e-p coupling and phonon excitation, and a small energy difference of donor-acceptor states. The internal quantum efficiency for charge separation can reach up to 99.6% and improved optical absorption is also observed in this heterostructure, making the BP/InSe heterostructure a compelling optoelectronic material.