Observation of biexcitons in nanocrystal solids in the presence of photocharging

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buir.contributor.authorDemir, Hilmi Volkan
buir.contributor.orcidDemir, Hilmi Volkan|0000-0003-1793-112X
dc.citation.epage4809en_US
dc.citation.issueNumber6en_US
dc.citation.spage4799en_US
dc.citation.volumeNumber7en_US
dc.contributor.authorCihan, A. F.en_US
dc.contributor.authorMartinez, P. L. H.en_US
dc.contributor.authorKelestemur Y.en_US
dc.contributor.authorMutlugun, E.en_US
dc.contributor.authorDemir, Hilmi Volkanen_US
dc.date.accessioned2015-07-28T11:57:16Z
dc.date.available2015-07-28T11:57:16Z
dc.date.issued2013en_US
dc.departmentDepartment of Physicsen_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.departmentInstitute of Materials Science and Nanotechnology (UNAM)en_US
dc.description.abstractT In nanocrystal quantum dots (NQDs), generating multiexcitons offers an enabling tool for enhancing NQD-based devices. However, the photocharging effect makes understanding multiexciton kinetics in NQD solids fundamentally challenging, which is critically important for solid-state devices. To date, this lack of understanding and the spectral temporal aspects of the multiexciton recombination still remain unresolved in solid NQD ensembles, which is mainly due to the confusion with recombination of carriers in charged NQDs. In this work, we reveal the spectral temporal behavior of biexcitons (BXs) in the presence of photocharging using near-unity quantum yield CdSe/CdS NQDs exhibiting substantial suppression of Auger recombination. Here, recombinations of biexcitons and single excitons (Xs) are successfully resolved in the presence of trions in the ensemble measurements of time-correlated single-photon counting at variable excitation intensities and varying emission wavelengths. The spectral behaviors of BXs and Xs are obtained for three NQD samples with different core sizes, revealing the strength tunability of the X X interaction energy in these NQDs. The extraction of spectrally resolved X, BX, and trion kinetics, which are otherwise spectrally unresolved, is enabled by our approach introducing integrated time-resolved fluorescence. The results are further experimentally verified by cross-checking excitation intensity and exposure time dependencies as well as the temporal evolutions of the photoluminescence spectra, all of which prove to be consistent. The BX and X energies are also confirmed by theoretical calculations. These findings fill an important gap in understanding the spectral dynamics of multiexcitons in such NQD solids under the influence of photocharging effects, paving the way to engineering of multiexciton kinetics in nanocrystal optoelectronics, including NQD-based lasing, photovoltaics, and photodetection.en_US
dc.identifier.doi10.1021/nn305259gen_US
dc.identifier.issn1936-0851
dc.identifier.urihttp://hdl.handle.net/11693/11254
dc.language.isoEnglishen_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.isversionofhttp://dx.doi.org/10.1021/nn305259gen_US
dc.source.titleACS Nanoen_US
dc.subjectSemiconductor Quantum Dotsen_US
dc.subjectMultiexciton Generationen_US
dc.subjectMultiexciton Recombinationen_US
dc.subjectBiexcitonen_US
dc.subjectTrionen_US
dc.subjectTime-resolved Fluorescenceen_US
dc.titleObservation of biexcitons in nanocrystal solids in the presence of photochargingen_US
dc.typeArticleen_US
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