Phonon-phonon interaction assisted electron-hole recombination in WSe2/hBN van der Waals heterostructure

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. Published under an exclusive license by AIP Publishing.

Automated summary

The study found that the out-of-plane phonon of hBN strongly couples with the WSe2 out-of-plane A(1)' phonon at the interface, enhancing the electron-phonon interaction and accelerating the electron-hole recombination dynamics.