title: Reversible photoswitching of triplet-triplet annihilation upconversion using dithienylethene photochromic switches.
abstract: Reversible photoswitched triplet-triplet annihilation upconversion (TTA UC) was demonstrated with dithienylethene (DTE) derivatives as the photochromic units, 2,6-diiodoBodipy as the triplet photosensitizer, and perylene as the triplet acceptor/emitter. The TTA UC is undisturbed by the open-form DTE but can be switched OFF upon photoirradiation of the mixture of the three components at 254 nm, i.e., by the closed-form DTE. Subsequent visible light irradiation restores the TTA UC. By studying the competitive triplet-state energy-transfer processes with nanosecond time-resolved transient difference absorption and fluorescence spectroscopy, we confirmed that the quenching of the perylene triplet excited state by closed-form DTE is dominant among the four possible quenching processes.
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology , E-208 West Campus, 2 Ling-Gong Road, Dalian 116024, P. R. China.
authors.forename: Xiaoneng
authors.initials: X
authors.lastname: Cui
authors.forename: Jianzhang
authors.initials: J
authors.lastname: Zhao
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.forename: Yilong
authors.initials: Y
authors.lastname: Zhao