Photon upconversion based on sensitized triplet-triplet annihilation (TTA) is a nonlinear process involving multiple diffusion controlled energy transfer steps, ultimately resulting in the generation of delayed singlet fluorescence that is of higher energy with respect to the incident light. In this presentation, recent work related to using Ru(II) based sensitizers with notably long excited state lifetimes will be described. Blue and near-visible upconverted emission from anthracene sensitized by the green-absorbing [Ru(5-pyrenyl-1,10-phenanthroline)]3(PF6)2 ([Ru(py-phen)3]2+) has been investigated in acetonitrile.  Non-coherent green light at ultralow intensities (�Ws) has been used for selective sensitizer excitation in the presence of micromolar concentrations of anthracene, generating anti-Stokes singlet fluorescence in the latter. The resultant data are consistent with photon upconversion proceeding from sensitized TTA of the anthracene acceptor molecules, confirmed in part through transient absorption spectroscopy and dynamic emission experiments.

Green-to-blue photon upconversion with ultralow non-coherent excitation

243rd National Meeting (2012)

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