Improving Triplet-Triplet Annihilation Upconversion Output by a Triplet Mediator Approach: Mechanistic Insights on Homo and Hetero-Annihilation in Three-Component Systems.
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Kandappa SK, Gray V
J. Am. Chem. Soc. 147 (44) 40214-40224 [2025-11-05; online 2025-10-24]
Triplet-triplet annihilation photon upconversion (TTA-UC) is a promising strategy for converting low-energy photons into higher-energy emission, with potential applications in solar energy harvesting, bioimaging, and photocatalysis. A challenge in TTA-UC systems is minimizing the reabsorption of upconverted photons by the annihilator molecules. To address this, we present a mediator-assisted TTA-UC approach utilizing a neutral mediator molecule to facilitate upconversion in the ultraviolet (UV) and visible regions. Our study introduces a general protocol, and through detailed kinetic modeling, we elucidate the underlying mechanism, highlighting the role of hetero-TTA (triplet-triplet annihilation between the mediator and annihilator). Notably, we report the first estimation of a hetero-TTA rate constant, which exceeds the homo-TTA rate by a factor of 2. This work broadens the design space for TTA-UC systems by enabling the use of neutral, noncovalently linked mediators, expanding beyond the conventional reliance on charged or covalently tethered species.
Spatial Mass Spectrometry [Service]
PubMed 41135045
DOI 10.1021/jacs.5c09906
Crossref 10.1021/jacs.5c09906