Invited: Colloidal Semiconductor Nanocrystals for Sensing and Optoelectronic Applications

Quantum confined semiconductor nanocrystals offer size-tunable energy gaps, large photoluminescence quantum efficiencies at room temperature, scalable synthesis, and low cost solution processing. Owing to these characteristics, significant interest exists in the development of these materials for use in optoelectronic and sensing applications. Despite high room temperature photoluminescence quantum yields that in some cases can approach unity, many important devices such as displays, lighting, and optical amplifiers experience elevated temperatures during operation, which has generally not received much attention. For three semiconductor compositions (cadmium selenide, indium phosphide, and silicon), we utilize static and time-resolved optical characterizations to improve understanding of carrier dynamics under operational conditions. Specifically, we measure quantum yield vs elevated temperature, reveal reversible as well as irreversible exciton quenching pathways, and investigate the role of surface termination on exciton integrity with temperature. This work points to strategies to improve upon the performance of these materials in high temperature applications. We have also made use of these materials in biological sensing applications where we make use of the large absorption cross-sections and high optical stability of some nanocrystals compositions. Using these materials, we report a selective, stable, fast and sensitive all-optical pathogen detection assay.