Jennifer A Hollingsworth

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Semiconductor nanocrystal quantum dots (NQDs) comprise an important class of inorganic fluorophores for applications from optoelectronics to biology. Unfortunately, to date, NQD optical properties (e.g., their efficient and particle-size-tunable photoluminescence) have been susceptible to instabilities at the bulk and single-particle levels. Specifically,(More)
The development of optical gain in chemically synthesized semiconductor nanoparticles (nanocrystal quantum dots) has been intensely studied as the first step toward nanocrystal quantum dot lasers. We examined the competing dynamical processes involved in optical amplification and lasing in nanocrystal quantum dots and found that, despite a highly efficient(More)
The growth of ultra-thick inorganic CdS shells over CdSe nanocrystal quantum dot (NQD) cores gives rise to a distinct class of NQD called the "giant" NQD (g-NQD). g-NQDs are characterized by unique photophysical properties compared to their conventional core/shell NQD counterparts, including suppressed fluorescence intermittency (blinking), photobleaching,(More)
We report on the dynamics of resonant energy transfer in monodisperse, mixed-size, and energy-gradient (layered) assemblies of CdSe nanocrystal quantum dots. Time-resolved and spectrally resolved photoluminescence directly reveals the energy-dependent transfer rate of excitons from smaller to larger dots via electrostatic coupling. The data show a rapid(More)
Infrared-emitting nanocrystal quantum dots (NQDs) have enormous potential as an enabling technology for applications ranging from tunable infrared lasers to biological labels. Notably, lead chalcogenide NQDs, especially PbSe NQDs, provide efficient emission over a large spectral range in the infrared, but their application has been limited by instability in(More)
We use a simple device architecture based on a poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated indium tin oxide anode and a LiF/Al cathode to assess the effects of shell thickness on the properties of light-emitting diodes (LEDs) comprising CdSe/CdS core/shell nanocrystal quantum dots (NQDs) as the emitting layer. Specifically, we(More)
Spatial confinement of electronic excitations in semiconductor nanocrystals (NCs) results in a significant enhancement of nonradiative Auger recombination (AR), such that AR processes can easily dominate the decay of multiexcitons. AR is especially detrimental to lasing applications of NCs, as optical gain in these structures explicitly relies on emission(More)
The development of nanocrystal quantum dots (NQDs) with suppressed nonradiative Auger recombination has been an important goal in colloidal nanostructure research motivated by the needs of prospective applications in lasing devices, light-emitting diodes, and photovoltaic cells. Here, we conduct single-nanocrystal spectroscopic studies of recently developed(More)
Biexciton photoluminescence (PL) quantum yields (Q(2X)) of individual CdSe/CdS core-shell nanocrystal quantum dots with various shell thicknesses are derived from independent PL saturation and two-photon correlation measurements. We observe a near-unity Q(2X) for some nanocrystals with an ultrathick 19-monolayer shell. High Q(2X)'s are, however, not(More)
A new class of nanocrystal quantum dot (NQD), the "giant" NQD (g-NQD), was investigated for its potential to address outstanding issues associated with the use of NQDs as down-conversion phosphors in light-emitting devices, namely, insufficient chemical/photostability and extensive self-reabsorption when packed in high densities or in thick films. Here, we(More)