Core/shell heterostructures have been widely explored as a means to adjust the photophysical properties of QDs, and can be used to increase their brightnessas fluorophores in two ways: (1) maximizing the photoluminescence quantum yield(QY) through electronic and chemical isolation of the core; and (2) increasingthe excitation rate (absorption cross-section) by building a high density ofelectronic states at energies above the shell bandgap. These two roles for theshell present a potential trade-off in terms of shell material. A wide bandgapshell imposes large electronic barriers for carrier access to the surface butwill be less able to contribute to absorption, while a narrower gap shell couldparticipate in light harvesting but may make it harder to achieve high QY. Iwill present recent work on the development of core/shell QDs with modest bandoffsets that nonetheless maintain high QY in aqueous solution, and newexperiments that explore the limits of alternating-layer addition approaches tocore/shell nanostructures.

Challenging the trade-offs in synthesis and application of core/shell
nanocrystal fluorophores

242nd National Meeting (2011)

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Challenging the trade-offs in synthesis and application of core/shell nanocrystal fluorophores