Spectral conversion of light radiation is essential for a variety of modern-day technologies including displays, photovoltaics, data storage, and cancer therapy. In the past decades, a variety of luminescent materials, including organic dyes and semiconductor quantum dots, were developed to realize photon energy conversion in the ultraviolet (UV) to near infrared (NIR) spectral range. However, practical application of these techniques is typically limited by constraints such as toxicity and/or poor stability. In this context, lanthanide-doped upconversion nanoparticles have been developed as a promising alternative to conventional luminescent nanomaterials. By comparison, these nanoparticles offer low cytotoxicity, sharp emission peaks, long-lived excited electronic states, as well as high stability against photo bleaching and chemical degradation. In this talk, I focus on our recent efforts on lanthanide-doped core-shell nanoparticles that are generally composed of a layer-by-layer structure with a set of lanthanide ions incorporated into separate layer. I discuss how to fabricate these nanostructures by wet-chemistry method and how to characterize the nanostructure by a combination of electron microscopy and luminescence spectroscopy. Examples will be given to demonstrate how to enhance multiphoton upconversion emissions for exciting new technological applications.
References:
1. X. Chen, D. Peng, Q. Ju, F. Wang*, Photon upconversion in core-shell nanoparticles. Chem. Soc. Rev. 2015, 44, 1318.
2. B. Chen, D. Peng, X. Chen, X. Qiao, X. Fan, F. Wang*, Establishing the Structural Integrity of Core–Shell Nanoparticles against Elemental Migration using Luminescent Lanthanide Probes, Angew. Chem. Int. Ed. 2015, 54, 12788.
3. X. Chen, L. Jin, W. Kong, T. Sun, W. Zhang, X. Liu, J. Fan, S. F. Yu*, Feng Wang*, Confining energy migration in upconversion nanoparticles towards deep ultraviolet lasing, Nature Communications 2016, 7, 10304, doi: 10.1038/ncomms10304...