Ultrafast charge transfer in anisotropic black phosphorus/ TiS3 heterostructures for photoconversion

Construction of two-dimensional van der Waals (vdW) heterostructure has been well recognized to provide an avenue towards designing functional optoelectronic and photovoltaic devices. Here, a type-II vdW heterostructure consisting of anisotropic black phosphorus (BP) and ${\mathrm{TiS}}_{3}$ possessing ultrafast interlayer charge transfer for photoconversion is established using ab initio nonadiabatic molecular dynamics with HSE06 hybrid functional. The present results demonstrate that the ultrafast interlayer electron and hole transfer occur within 42 and 467 fs, respectively, which is mainly ascribed to the electron-phonon coupling dominantly contributed by an interlayer breathing mode and the stretching mode of ${\mathrm{TiS}}_{3}$ induced by in-plane vibration of interfacial S-S pairs. Moreover, it is discovered that the interlayer charge transfer process can be effectively controlled by the external electric field (EEF); i.e., positive (negative) EEF can sustain (slow down) the ultrafast carrier dynamics and facilitate (degenerate) the separation of electron and hole. The present findings pave the way to developing high-performance functional optoelectronic devices based on two-dimensional vdW heterostructure.