Coherent Exciton Delocalization in Strongly Coupled
Quantum Dot Arrays
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Abstract
Quantum dots (QDs) coupled into disordered
arrays have exhibited
the intriguing property of bulk-like transport while maintaining discrete
excitonic optical transitions. We have utilized ultrafast cross-polarized
transient grating (CPTG) spectroscopy to measure electron–hole
wave function overlap in CdSe QD films with chemically modified surfaces
for tuning inter-QD electronic coupling. By comparing the CPTG decays
with those of isolated QDs, we find that excitons coherently delocalize
to form excited states more than 200% larger than the QD diameter