  Many-body effect and strong Coulomb interaction in monolayer transition metal
dichalcogenides lead to shrink the intrinsic bandgap, originating from the
renormalization of electrical/optical bandgap, exciton binding energy, and
spin-orbit splitting. This renormalization phenomenon has been commonly
observed at low temperature and requires high photon excitation density. Here,
we present the augmented bandgap renormalization in monolayer MoS_2 anchored on
CsPbBr_3 perovskite quantum dots at room temperature via charge transfer. The
amount of electrons significantly transferred from perovskite gives rise to the
large plasma screening in MoS_2. The bandgap in heterostructure is red-shifted
by 84 meV with minimal pump fluence, the highest bandgap renormalization in
monolayer MoS_2 at room temperature, which saturates with further increase of
pump fluence. We further find that the magnitude of bandgap renormalization
inversely relates to Thomas-Fermi screening length. This provides plenty of
room to explore the bandgap renormalization within existing vast libraries of
large bandgap van der Waals heterostructure towards practical devices such as
solar cells, photodetectors and light-emitting-diodes.
