Title Enhancement of triplet-sensitized upconversion in rigid polymers via singlet exciton sink approach /
Authors Raišys, Steponas ; Juršėnas, Saulius Antanas ; Simon, Yoan C ; Weder, Christoph ; Kazlauskas, Karolis
DOI 10.1039/c8sc02151a
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Is Part of Chemical science.. Cambridge : Royal Society of Chemistry. 2018, vol. 9, no 33, p. 6796-6802.. ISSN 2041-6520. eISSN 2041-6539
Keywords [eng] 9,10- diphenylanthracene ; Forster resonant energy transfer ; singlet exciton diffusion ; exciton trapping
Abstract [eng] To increase the practical usefulness of solid-state sensitized upconversion (UC) materials as components of solar energy harvesting systems, it is important to identify and suppress loss mechanisms, and increase the UC quantum yield (ΦUC). Here we focus on a benchmark UC system consisting of the emitter 9,10-diphenylanthracene (DPA) and the sensitizer platinum octaethylporphyrin (PtOEP) in a rigid poly(methyl methacrylate) (PMMA) matrix, and show that one of the major losses originates from Förster resonant energy transfer (FRET) from DPA back to PtOEP. Even though DPA emission lies within the PtOEP transparency window, the quantitative assessment of singlet exciton diffusion for samples with a high DPA content evidences that long-range FRET results in effective exciton trapping by PtOEP. A dramatic factor-of-6 reduction of the DPA emission quantum yield occurs even at PtOEP concentrations as low as 0.05 wt%. To alleviate this problem, we demonstrate a new concept based on the introduction of highly emissive sink sites to trap the singlet excitons produced upon annihilation prior to their quenching by the sensitizer. For DPA/PtOEP blends in PMMA, 1,6-bis-[2,5-di(dodecyloxyphenyl)ethynyl]pyrene is shown to be a useful sink, which results in 1.5-fold increase of the ΦUC. A maximum ΦUC of 2.7% was achieved, which is among the highest reported values for rigid sensitized UC polymers.
Published Cambridge : Royal Society of Chemistry
Type Journal article
Language English
Publication date 2018