Document Type

Article

Rights

This item is available under a Creative Commons License for non-commercial use only

Disciplines

Optics, Organic Chemistry, Physical chemistry

Publication Details

Journal Physical Chemistry Letters

Abstract

The efficiency of photon upconversion via triplet–triplet annihilation is characterized by an upconversion quantum yield (ΦUC); however, uncertainties remain for its determination. Here, we present a new approach for the relative measurement of ΦUC for green-to-blue upconversion using BODIPY–pyrene donor–acceptor dyad (BD1) as a heavy-atom-free triplet sensitizer. This new approach exploits broad fluorescence from a charge-transfer (CT) state of BD1, which possesses (i) a significant Stokes shift of 181 nm in dichloromethane and (ii) a comparably high CT-fluorescence quantum yield (Φref = 7.0 ± 0.2%), which is independent from oxygen presence and emitter (perylene) concentration while also exhibiting a linear intensity dependence. On the basis of this, we developed an upconversion reference using the BD1 sensitizer mixed with perylene (1 × 10–5 M/1 × 10–4 M) in dichloromethane. With this reference system, we investigated the performance of three BODIPY donor–acceptor dyads in the upconversion process and achieved one of the highest ΦUC of 6.9 ± 0.2% observed for heavy-atom-free sensitizers to date.

DOI

https://doi.org/10.1021/acs.jpclett.0c01902

Available for download on Saturday, August 07, 2021

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