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Plasmonic Hot Carrier Induced Photosensitization of CdSe Quantum Dots: Role of Phonons
journal contribution
posted on 2020-05-22, 10:14 authored by Sandhya KM, Bikas C. DasGeneration
of hot carriers from nonradiative surface-plasmon decay
and subsequent injection into the semiconductor is the start of a
new paradigm in the field of optoelectronics and photocatalysis. However,
the role of phonons in the plasmon-induced charge-transfer process
is mainly unexplored. We utilized a technique called photoassisted
scanning tunneling spectroscopy (PATS) to probe it by measuring the
photoconduction of CdSe QDs deposited on gold and conducting n-type
silicon. The ratio of currents in the light and dark shows much higher
for CdSe QDs thin film on the gold substrate than the n-type silicon.
Here, phonons impersonate an essential role in a higher generation
rate and ultrafast injection of hot carriers into CdSe QDs interfaced
with gold substrate. Scanning tunneling spectroscopy results recorded
under the light with band-edge-like peaks located inside the band
gap of CdSe QDs on gold indicate the quantum tunneling of plasmonic
hot carriers to the defect levels directly, which would contribute
significantly to enhance the photoresponse property of CdSe QDs.