Visible-to-ultraviolet (<340 nm) photon upconversion by triplet-triplet annihilation in solvents
| Autor: | Atsushi Kaiho, Noriko Kiyoyanagi, Yoichi Murakami, Ayumu Motooka, Kazuki Niimi, Riku Enomoto |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Quenching (fluorescence) Solvatochromism General Physics and Astronomy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology medicine.disease_cause Photochemistry 01 natural sciences Photon upconversion 0104 chemical sciences Specific orbital energy Solvent Physics - Chemical Physics medicine Quantum efficiency Physical and Theoretical Chemistry 0210 nano-technology Ultraviolet Common emitter |
| Popis: | In this article, visible-to-ultraviolet photon upconversion (UV-UC) by triplet-triplet annihilation in the emission range shorter than 340 nm, which is previously unexplored, is presented and the relevant physicochemical characteristics are elucidated. Investigations were carried out in several deaerated solvents using acridone and naphthalene derivatives as a sensitizer and emitter, respectively. Both upconversion quantum efficiency and sample photostability under continuous photoirradiation strongly depended on the solvent. The former dependence is governed by the solvent polarity, which affects the triplet energy level matching between the sensitizer and emitter because of the solvatochromism of the sensitizer. To elucidate the latter, first we investigated the photodegradation of samples without the emitter, which revealed that the sensitizer degradation rate is correlated with the difference between the frontier orbital energy levels of the sensitizer and solvent. Inclusion of the emitter effectively suppressed the degradation of the sensitizer, which is ascribed to fast quenching of the triplet sensitizer by the emitter and justifies the use of ketonic sensitizers for UV-UC in solvents. A theoretical model was developed to acquire insight into the observed temporal decays of the upconverted emission intensity under continuous photoirradiation. The theoretical curves generated by this model fitted the experimental decay curves well, which allowed the reaction rate between the emitter and solvent to be obtained. This rate was also correlated with difference between the frontier orbital energy levels of the emitter and solvent. Finally, based on the acquired findings, general design guidelines for developing UV-UC samples were proposed. Comment: Main Body (27 pages, single column and double-spaced) + Supplementary Information (27 pages, single column and double-spaced) |
| Databáze: | OpenAIRE |
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