Single Platinum Atom Doping to Silver Clusters Enables Near-Infrared-to-Blue Photon Upconversion

Yoshiki Niihori; Yuki Wada; Masaaki Mitsui

doi:10.1002/anie.202013725

Single Platinum Atom Doping to Silver Clusters Enables Near-Infrared-to-Blue Photon Upconversion

Angew Chem Int Ed Engl. 2021 Feb 8;60(6):2822-2827. doi: 10.1002/anie.202013725. Epub 2021 Jan 12.

Authors

Yoshiki Niihori¹, Yuki Wada¹, Masaaki Mitsui¹

Affiliation

¹ Department of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishiikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.

PMID: 33295118
DOI: 10.1002/anie.202013725

Abstract

Photon upconversion (UC) from near-infrared (NIR) to visible has been realized using singlet-to-triplet absorption of sensitizers, which are currently limited to osmium complexes and semiconductor nanocrystals. Motivated by the atomically precise tunability of electronic structure and photophysical properties of noble metal clusters, which often possess absorption bands that extend into the NIR region, we investigated MAg₂₄ (SR)₁₈ (M=Ag, Pt; SR=2,4-dimethylbenzenethiolate) clusters as a new NIR-absorbing sensitizer for triplet-triplet annihilation UC. Combined with a blue light emitter, the NIR excitation (λ_ex =785 nm) of Ag₂₅ (SR)₁₈ results in no UC emission, while PtAg₂₄ (SR)₁₈ exhibits strong UC emission. This enhancement is primarily due to a significant increase in the intersystem crossing quantum yield of the cluster associated with the spin-orbit coupling enhancement in the M@Ag₁₂ core.

Keywords: intersystem crossing; ligand-protected metal clusters; superatoms; triplet sensitizers; triplet-triplet annihilation photon upconversion.