Phonon–phonon Interaction Assisted Electron–hole Recombination in WSe$_2$/hBN van der Waals Heterostructure

Abstract

Photogenerated charge carrier dynamics at the WSe2/hBN van der Waals interface play an important role in optical device applications. The carrier behavior has been argued to be related to the interlayer phonon–phonon interaction in the heterostructure. However, the effect of the interlayer coupling on the electron–hole recombination dynamics is still unclear. Using the ab initio nonadiabatic molecular dynamics approach, we investigate the photoexcited electron dynamics at the interface, which has a type I energy alignment. The out-of-plane phonon of hBN is found to strongly couple with the WSe2 out-of-plane A′1 phonon, enhancing the electron–phonon interaction and accelerating the electron–hole recombination compared to pristine WSe2. Our work provides valuable guidance on the design of novel two-dimensional optoelectronic and opto-phononic devices.