Excitonics of colloidal nanocrystals for next-generation optoelectronics

Owing to the tremendous progress in the past decade, semiconductor nanocrystals that are grown by low-temperature solution-phase epitaxy have evolved into highly promising material systems for optoelectronics with ever increasing interest from the industry. However, fundamental challenges exist in conventional nanocrystals hampering their energy-efficient optoelectronic devices. In this thesis, we addressed important scientific problems and overcome various technological hurdles through optical physics discoveries and innovative nanomaterial processing. Specifically, we have proposed, designed and developed next generation of nanocrystals that exhibit superior optical and material properties than those of the conventional nanocrystals. Mastering intra- and inter-particle excitonic processes in these nanocrystals and their hybrids empowered us to control and tailor the desired photonic response. Our key achievements include demonstration of record high modal gain coefficients and giant nonlinear absorption cross-section in atomically-flat nanocrystals, ultralow-threshold all-solution processed quantum dot lasers and unprecedentedly strong exciton transport in self-assembled nanocrystals.