Semiconductor nanocrystals (NCs) have recently been shown to sensitize triplet states in surface-adsorbed molecular acceptors, serving as a surrogate to traditional molecular sensitizers. These findings have implications in fields as diverse as optoelectronics, solar energy conversion, and photobiology. In this work, ultrafast spectroscopy is employed to develop the mechanism(s) and determine the associated rates for molecular triplet-acceptor formation at the molecule/semiconductor nanocrystal interface. Efficient transfer of triplet exciton energy (&gt;90%) from CdSe NCs to surface-anchored molecular acceptors has been shown to occur through direct ‘Dexter-like’ triplet-triplet energy transfer. The surfaced anchored molecular triplet features lifetimes on the millisecond timescale, representing a six order-of-magnitude increase with respect to “naked” CdSe nanocrystals. Furthermore, this excitation energy was quantitatively extracted into bulk solution through collisions with freely diffusing molecular triplet acceptors. PbS semiconductor NCs were also investigated for use as triplet sensitizers. In stark contrast to the processes on CdSe, formation of TIPS-pentacene molecular triplet excitons bound on the surface of PbS nanocrystals occurred in an unprecedented time delayed fashion reminiscent of supramolecular photochemistry processes. This presentation will discuss our most current findings related to both classes of materials.

Supramolecular strategies enabling directional energy flow from quantum dots

254th National Meeting (2017)

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