Learn More
Because of the strong spatial confinement of electronic wave functions and reduced dielectric screening, the effects of carrier-carrier Coulomb interactions are greatly enhanced in semiconductor nanocrystals (NCs) compared with those in bulk materials. These interactions open a highly efficient decay channel via Auger recombination, which represents a(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)
One consequence of strong spatial confinement of electronic wave functions in semiconductor nanocrystals (NCs) is a significant enhancement in carrier-carrier Coulomb interactions. This effect leads to a number of novel physical phenomena including ultrafast decay of multiple electron-hole pairs (multiexcitons) by Auger recombination and high-efficiency(More)
We report the direct observation of spin-singlet dark excitons in individual single-walled carbon nanotubes through low-temperature micro-magneto-photoluminescence spectroscopy. A magnetic field (B) applied along the tube axis brightened the dark state, leading to the emergence of a new emission peak. The peak rapidly grew in intensity with increasing B at(More)
In this communication, we demonstrate a new approach to sensitization of Ru-polypyridine complexes by using semiconductor nanocrystal quantum dots (NQDs). When mixed in solution, the complexes functionalized by carboxylic groups adsorb onto the surface of the NQDs. Excitation of NQDs by 400 nm light leads to fast, 5 ps hole transfer from the photoexcited(More)
Nanocomposite materials provide the possibility for multifunctional properties in contrast with their more-limited single-component counterparts. Here, we report the synthesis and characterization of the first all-inorganic core/shell hybrid magnetic-optical nanoparticle, cobalt/cadmium selenide. The core/shell nanocrystals are prepared in a facile one-pot(More)
Nanomaterials with efficient carrier multiplication (CM), that is, generation of multiple electron-hole pairs by single photons, have been the object of intense scientific interest as potential enablers of high efficiency generation-III photovoltaics. In this work, we explore nanocrystal shape control as a means for enhancing CM. Specifically, we(More)
Using modern colloidal chemistry, semiconductor nanocrystals (NCs), known also as NC quantum dots, can be fabricated with nearly atomic precision with a wide range of sizes and shapes. They exhibit high photoluminescence quantum yields, narrow size-controlled emission lines, and can easily be manipulated into complex two-dimensional (2D) and 3D assemblies.(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)
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)