A composite electrodynamic mechanism to reconcile spatiotemporally resolved exciton transport in quantum dot superlattices.

Quantum dot (QD) solids are promising optoelectronic materials; further advancing their device functionality requires understanding their energy transport mechanisms. The commonly invoked near-field Förster resonance energy transfer (FRET) theory often underestimates the exciton hopping rate in QD solids, yet no consensus exists on the underlying cause. In response, we use time-resolved ultrafast stimulated emission depletion (STED) microscopy, an ultrafast transformation of STED to spatiotemporally resolve exciton diffusion in tellurium-doped cadmium selenide-core/cadmium sulfide-shell QD superlattices.

Nanometer-Scale Spatial and Spectral Mapping of Exciton Polaritons in Structured Plasmonic Cavities.

Exciton polaritons (EPs) are ubiquitous light-matter excitations under intense investigation as test beds of fundamental physics and as components for all-optical computing. Owing to their unique attributes and facile experimental tunability, EPs potentially enable strong nonlinearities, condensation, and superfluidity at room temperature. However, the diffraction limit of light and the momentum content of fast electron probes preclude the characterization of EPs in nanoscale structured cavities exhibiting energy-momentum dispersion.

Imaging Infrared Plasmon Hybridization in Doped Semiconductor Nanocrystal Dimers.

Carrier-doped semiconductor nanocrystals (NCs) offer strong plasmonic responses at frequencies beyond those accessible by conventional plasmonic nanoparticles. Like their noble metal analogues, these emerging materials can harness free space radiation and confine it to the nanoscale but at resonance frequencies that are natively infrared and spectrally tunable by carrier concentration. In this work we combine monochromated STEM-EELS and theoretical modeling to investigate the capability of colloidal indium tin oxide (ITO) NC pairs to form hybridized plasmon modes, providing an additional route to influence the IR plasmon spectrum.