title: Direct observation of triplet energy transfer from semiconductor nanocrystals.
abstract: Triplet excitons are pervasive in both organic and inorganic semiconductors but generally remain confined to the material in which they originate. We demonstrated by transient absorption spectroscopy that cadmium selenide semiconductor nanoparticles, selectively excited by green light, engage in interfacial Dexter-like triplet-triplet energy transfer with surface-anchored polyaromatic carboxylic acid acceptors, extending the excited-state lifetime by six orders of magnitude. Net triplet energy transfer also occurs from surface acceptors to freely diffusing molecular solutes, further extending the lifetime while sensitizing singlet oxygen in an aerated solution. The successful translation of triplet excitons from semiconductor nanoparticles to the bulk solution implies that such materials are generally effective surrogates for molecular triplets. The nanoparticles could thereby potentially sensitize a range of chemical transformations that are relevant for fields as diverse as optoelectronics, solar energy conversion, and photobiology.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Cédric
authors.initials: C
authors.lastname: Mongin
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Sofia
authors.initials: S
authors.lastname: Garakyaraghi
authors.affiliation: Department of Physics and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Razgoniaeva
authors.affiliation: Department of Physics and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Zamkov
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Felix N
authors.initials: FN
authors.lastname: Castellano