Coherent exciton delocalization in strongly coupled quantum dot arrays.

Crisp, Ryan W; Schrauben, Joel N; Beard, Matthew C; Luther, Joseph M; Johnson, Justin C · Nano Lett · 2013

basic_science · Level V

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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.

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