Full shell coating or cation exchange enhances luminescence

• Published in: Nature communications Vol. 12; no. 1; pp. 6178 - 10
• Main Authors: Zhang, Yi, Lei, Pengpeng, Zhu, Xiaohui, Zhang, Yong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.10.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1019/1021; 639/624/399/354; Cation exchange; Cation exchanging; Core-shell structure; Energy transfer; Humanities and Social Sciences; Interfacial energy; Luminescence; multidisciplinary; Nanoparticles; Science; Science (multidisciplinary); Shells; Upconversion
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26490-7

Core-shell structure is routinely used for enhancing luminescence of optical nanoparticles, where the luminescent core is passivated by an inert shell. It has been intuitively accepted that the luminescence would gradually enhance with the coverage of inert shell. Here we report an “off-on” effect at the interface of core-shell upconversion nanoparticles, i.e., regardless of the shell coverage, the luminescence is not much enhanced unless the core is completely encapsulated. This effect indicates that full shell coating on the luminescent core is critical to significantly enhance luminescence, which is usually neglected. Inspired by this observation, a cation exchange approach is used to block the energy transfer between core nanoparticle and surface quenchers. We find that the luminescent core exhibits enhanced luminescence after cation exchange creates an effective shell region. These findings are believed to provide a better understanding of the interfacial energy dynamics and subsequent luminescence changes. Core-shell designs enhance the luminescence of lanthanide-doped upconversion nanoparticles (UCNPs), but the effect of shell coverage was insufficiently characterized. Here the authors demonstrate, on a series of core-shell UCNPs with various shell coverage ratios, an on-off effect by which luminescence is enhanced only when a full coverage is achieved.