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论文类型：期刊论文

发表时间：2017-12-01

发表刊物：DYES AND PIGMENTS

收录刊物：Scopus、SCIE、EI

卷号：147

页面范围：560-572

ISSN号：0143-7208

关键字：Charge separation; Charge recombination; FRET; Intersystem crossing; Triplet state

摘要：Two triads (BDP-SQ and Styryl-BDP-SQ) were prepared with Bodipy, styrylBodipy and Squaraine (SQ) units. SQ shows unexpected efficient intersystem crossing (ISC. phi(T) = 50%), which is attributed to S-1 -> T-1 transition. In the two triads, the Forster Resonance Energy Transfer (FRET) direction, as well as the spatial localization of the T-1 state, was judiciously tuned. The cascade photophysical properties of the triads were studied with steady-state and time -resolved optical spectroscopies, as well as with electrochemical characterization and theoretical computations. We show that triplet state was produced in triad BDP-SQ upon photoexcitation, but in Styryl-BDP-SQ the fast FRET and the charge separation (CS) processes compete with the ISC of the SQ unit, and no triplet state was formed upon photoexcitation. The singlet energy transfer kinetics were found to be 1.6 and 0.6 ps, respectively and are solvent polarity dependent. Charge transfer was confirmed with ultrafast transient absorption spectroscopy. (C) 2017 Elsevier Ltd. All rights reserved.