  Understanding and controlling the nanoscale transport of excitonic
quasiparticles in atomically thin 2D semiconductors is crucial to produce
highly efficient nano-excitonic devices. Here, we present a nano-gap device to
selectively confine excitons or trions of 2D transition metal dichalcogenides
at the nanoscale, facilitated by the drift-dominant exciton funnelling into the
strain-induced local spot. We investigate the spatio-spectral characteristics
of the funnelled excitons in a WSe2 monolayer (ML) and converted trions in a
MoS2 ML using hyperspectral tip-enhanced photoluminescence (TEPL) imaging with
<15 nm spatial resolution. In addition, we dynamically control the exciton
funnelling and trion conversion rate by the GPa scale tip pressure engineering.
Through a drift-diffusion model, we confirm an exciton funnelling efficiency of
~25 % with a significantly low strain threshold (~0.1 %) which sufficiently
exceeds the efficiency of ~3 % in previous studies. This work provides a new
strategy to facilitate efficient exciton transport and trion conversion of 2D
semiconductor devices.
