Approaching the Spin-Statistical Limit in Visible-to-Ultraviolet Photon Upconversion
Artikel i vetenskaplig tidskrift, 2022

Triplet-triplet annihilation photon upconversion (TTA-UC) is a process in which triplet excitons combine to form emissive singlets and holds great promise in biological applications and for improving the spectral match in solar energy conversion. While high TTA-UC quantum yields have been reported for, for example, red-to-green TTA-UC systems, there are only a few examples of visible-to-ultraviolet (UV) transformations in which the quantum yield reaches 10%. In this study, we investigate the performance of six annihilators when paired with the sensitizer 2,3,5,6-tetra(9H-carbazol-9-yl)benzonitrile (4CzBN), a purely organic compound that exhibits thermally activated delayed fluorescence. We report a record-setting internal TTA-UC quantum yield (φUC,g) of 16.8% (out of a 50% maximum) for 1,4-bis((triisopropylsilyl)ethynyl)naphthalene, demonstrating the first example of a visible-to-UV TTA-UC system approaching the classical spin-statistical limit of 20%. Three other annihilators, of which 2,5-diphenylfuran has never been used for TTA-UC previously, also showed impressive performances with φUC,g above 12%. In addition, a new method to determine the rate constant of TTA is proposed, in which only time-resolved emission measurements are needed, circumventing the need for more challenging transient absorption measurements. The results reported herein represent an important step toward highly efficient visible-to-UV TTA-UC systems that hold great potential for driving high-energy photochemical reactions.


Axel Olesund

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Jessica Johnsson

Student vid Chalmers

Fredrik Edhborg

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Shima Ghasemi

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Kasper Moth-Poulsen

Institucio Catalana de Recerca i Estudis Avancats

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

Bo Albinsson

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 144 8 3706-3716

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Atom- och molekylfysik och optik

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