Enhanced chiroptic properties of nanocomposites of achiral plasmonic nanoparticles decorated with chiral dye-loaded micelles.

Zhao, Tonghan; Meng, Dejing; Hu, Zhijian; Sun, Wenjing; Ji, Yinglu; Han, Jianlei; Jin, Xue; Wu, Xiaochun et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

The development of circularly polarized luminescence (CPL)-active materials with both large luminescence dissymmetry factor (g<sub>lum</sub>) and high emission efficiency continues to be a major challenge. Here, we present an approach to improve the overall CPL performance by integrating triplet-triplet annihilation-based photon upconversion (TTA-UC) with localized surface plasmon resonance. Dye-loaded chiral micelles possessing TTA-UC ability are designed and attached on the surface of achiral gold nanorods (AuNRs). The longitudinal and transversal resonance peaks of AuNRs overlap with the absorption and emission of dye-loaded chiral micelles, respectively. Typically, 43-fold amplification of g<sub>lum</sub> value accompanied by 3-fold enhancement of upconversion are obtained simultaneously when Au@Ag nanorods are employed in the composites. More importantly, transient absorption spectra reveal a fast accumulation of spin-polarized triplet excitons in the composites. Therefore, the enhancement of chirality-induced spin polarization should be in charge of the amplification of g<sub>lum</sub> value. Our design strategy suggests that combining plasmonic nanomaterials with chiral organic materials could aid in the development of chiroptical nanomaterials.