Photochemically deoxygenating gels for triplet–triplet annihilation photon-upconversion performed under air?

Physical Chemistry Chemical Physics Pub Date: 2022-11-11 DOI: 10.1039/D2CP04532J

Abstract

For an efficient triplet–triplet annihilation photon upconversion (TTA-UC) process, matrices in which sensitizers and emitters are dispersed should not only allow molecular diffusions but also protect triplet excited states from oxygen-quenching. In this work, two photochemically deoxygenating gels, a poly(N-vinyl-2-pyrrolidone) (PVP) gel and a limonene gel, were prepared for TTA-UC performed under air. These two gels are optically transparent in the visible region and can serve as a scavenger for sensitized singlet oxygen. For the green-to-blue couple of platinum(II) octaethylporphyrin (Pt(OEP)) and 9,10-diphenylanthracene (DPA), under air, the bimolecular quenching rate constants were 6.73 × 108 dm3 mol?1 s?1 for the PVP gel and 1.54 × 109 dm3 mol?1 s?1 for the limonene gel, and the upconversion quantum yields were 9.1% and 1.9% in PVP and limonene gels, respectively. As matrices, the PVP gel can be employed in NIR-to-yellow, red-to-cyan, green-to-blue and blue-to-violet TTA-UC systems operating under air. TTA-UC systems of Pt(OEP)/DPA in PVP or limonene gels showed strong upconverted emission under air with non-coherent light of low optical power density as the excitation source.

Graphical abstract: Photochemically deoxygenating gels for triplet–triplet annihilation photon-upconversion performed under air
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