“Giant” or thick-shell core/shell quantum dots (gQDs) are an important class of solid-state quantum emitter. Without any encapsulation gQDs are characterized by strongly suppressed blinking, or even non-blinking behavior, and resistance to photobleaching at room temperature. In addition, non-radiative Auger processes are significantly reduced in this class of luminescent nanomaterial. Together, these qualities lead to novel functionality as photon sources for a range of ensemble and single-emitter applications, including down-conversion phosphors, direct excitation light-emitting diodes, single-biomolecule tracking, and single-photon generation for quantum applications. As a single-photon source, with judicious choice of core and shell size and composition, Auger processes can be tuned to either promote or suppress biexciton emission, the latter enabling a photon-pure on-demand single-photon source.

Thus, through chemical synthesis and internal interface control, we have made significant progress toward meeting the demands of an ideal quantum emitter – achieving on-demand, high-purity, room-temperature, spectrally tunable (blue-visible to telecommunications wavelengths) single-photon sources. However, to address other properties, including brightness, on-chip “plug-and-play” integration, chirality, polarization control and photon indistinguishability, we have looked to external environmental control to influence these properties that are not immediately under the influence of the synthetic chemist. Here, I will describe our efforts with collaborators to address these remaining challenges, primarily through integration into nanoantennas or plasmonic cavities. For example, we show the ability to achieve highly directional, radially polarized photons by exploiting the intrinsic stability of the gQD, as well as our developed scanning-probe-enabled strategy for precision placement of single nanocrystals into nanostructured surfaces, e.g., hybrid metal-dielectric bullseye antennas. Alternatively, in a separate collaboration, we have realized for the first time ultrafast (to 65 ps) and ultrabright (to ~12.6 MHz) room-temperature single-photon emission in the O and C telecommunications wavelength bands via coupling to solution-processed plasmonic nanocavities. Lastly, I will also address strategies using surface chemistry or interface modification to achieve circularly polarized emission or chiral quantum light sources, respectively.