Spectroscopy of Resonant Intermediate States for Triplet–Triplet Annihilation Upconversion in Crystalline Rubrene: Radical Ions as Sensitizers
| Autor: | J. Curtis Beimborn, Wyatt Zagorec-Marks, J. Mathias Weber |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Materials science Photoluminescence Physics::Optics 02 engineering and technology 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Photon upconversion Spectral line Ion chemistry.chemical_compound chemistry Excited state 0103 physical sciences General Materials Science Physics::Chemical Physics Physical and Theoretical Chemistry 0210 nano-technology Rubrene Spectroscopy Absorption (electromagnetic radiation) |
| Zdroj: | The Journal of Physical Chemistry Letters. 11:7212-7217 |
| ISSN: | 1948-7185 |
| DOI: | 10.1021/acs.jpclett.0c01999 |
| Popis: | Photoluminescence upconversion in crystalline rubrene can proceed without an added sensitizer, but the mechanism for this process has not been well-understood. In particular, the species responsible for photon absorption has not been identified to date. To gain insight into the identity of the intermediate state, we measured the near-infrared (NIR) upconversion photoluminescence (UCPL) excitation spectrum of rubrene crystals and found three distinct spectral features. The UCPL yield has a quartic dependence on the laser intensity, implying a four-photon process. On the basis of electronic spectra of radical cations and anions of rubrene, we propose a mechanism in which photoexcited radical anions and cations undergo recombination, forming an excited neutral triplet while conserving spin. The triplets formed this way ultimately undergo triplet-triplet annihilation, resulting in the observed photoluminescence. This mechanism explains the origin of the NIR absorption as well as the four-photon nature of the UCPL process. |
| Databáze: | OpenAIRE |
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