Elucidating the Primary Mechanism of Multiexciton Generation in Semiconductor Nanocrystals by Multi -Quantum Coherent Spectroscopy

  • Harel, Elad (PD/PI)

Project: Research project

Project Details

Description

Solar energy has the potential to provide a clean and inexpensive form of renewable energy,
but high efficiency remains a major, unsolved problem. A promising approach is multiexciton
generation (MEG) in which two or more electron-hole pairs or excitons are produced by
absorption of a single photon. MEG may increase photoconversion in bulk materials but suffers
from low efficiency. In contrast, MEG in quantum-confined structures such as semiconductor
nanocrystals may achieve high efficiency presumably due to the inhibition of deleterious
relaxation pathways. Understanding MEG processes in nanocrystals by both experiments and
theory is a defining principle that will guide advances in the next generation of solar cells.
Unfortunately and despite enormous effort, a complete picture of the mechanism of MEG is
lacking in large part because a direct measurement of the multi-exciton states involved remains
elusive. A novel experimental approach is proposed to perform the first direct measurements of
MEG in semiconductor nanocrystals, providing much needed insights into the mechanism of
coherent carrier relaxation processes. A unique aspect of this approach is that MEG may be
tracked in space and time across the entire solar spectrum in a single laser shot, thereby avoiding
artifacts and ambiguities that plague other measurement techniques.
StatusFinished
Effective start/end date2/1/151/31/17

Funding

  • Camille and Henry Dreyfus Foundation, Inc. (Check #24146)

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