The overall objective of this 5-year proposed research program is to conduct fundamental studies of intra-manifold excitonic energy redistribution in semiconductor nanocrystals (specifically colloidal cadmium chalcogenide and perovskite nanoplatelets, NPLs), and in complexes of nanoplatelets with molecules, in order to realize single photon emission from these particles at non-cryogenic temperatures. The specific objectives of the research program are: (i) to develop a temperature-dependent (4K RT) picture of excitonic structure and intra-manifold excitonic energy redistribution in quasi-2D colloidal Cd-chalcogenide and perovskite NPLs, including core-shell and core-crown NPL heterostructures, in order to potentially exploit their significant advantages (over spherical QDs) as quantum emitters; (ii) to understand how the spin angular momenta of the excitonic sublevels of NPLs dictate the probability of transfer of population out these sublevels to the triplet state of a molecule adsorbed to the NPL surface through triplet-triplet energy transfer, in order to use spin as a filter to “purify” the band-edge exciton of the NPL and thereby increase the indistinguishability and optical coherence lifetime of the photons it emits; and (iii) to use exciton delocalizing ligands (EDLs) and exciton confining ligands (ECLs), developed in our group, to control the size and shape of the excitonic wavefunction, and therefore the electron-hole exchange energy, in NPLs. The exchange energy primarily controls the energetic splitting, and the interconversion dynamics, between “bright” and “dark” excitonic manifolds and the rate of ZPL dephasing relative to radiative recombination of the exciton, the key parameter for a quantum emitter.
|Effective start/end date||9/15/20 → 9/14/25|
- Air Force Office of Scientific Research (FA9550-20-1-0364)