Engineering Orthogonal Upconversion through Selective Excitation in a Single Nanoparticle

Abstract

Orthogonal upconversion with color‐switchable emissions under different excitation conditions provides new chances to diverse frontier applications of luminescent materials. However, the previous orthogonal upconversion systems compulsorily require the precise control of spatial distributions of dopants and host compositions to avoid spectral cross‐talk, greatly limiting their synthesis and application. Herein, a conceptual design is presented to realize the orthogonal upconversion by selectively activating sensitizers and activators in nanostructure. In detail, the 915 nm laser, instead of the mostly used 980 nm, is adopted to activate the sensitizer Yb3+ because of the broad 2F5/2←2F7/2 absorption band; while it is non‐responsive to Er3+, consequently avoiding the spectral cross‐talk due to the simultaneous activation of both Er3+ and Yb3+ under 980 nm irradiation as shown in the previous works. Such a selective excitation strategy is able to realize the red/green, blue/red, and blue/green orthogonal upconversion in a single nanoparticle by simply altering the excitation wavelength from 915 to 1530 nm. More interestingly, it further allows for full‐color output by temporal control of the upconversion dynamics. The findings suggest a facile but effective approach to the design of smart luminescent materials, showing great potential in multi‐level anti‐counterfeiting, information security and biological applications.

High-Yb3+-Doped NaYbF4:10% Er@NaYF4 Alloyed Nanoparticles for Brightening Upconversion and Multi-Colorizing Information Encryption

“…Multicolor information encryption has been garnering increasing attention owing to its powerful confidentiality features in the field of anticounterfeiting. − Because the aUCNPs had a primary green emission at 544 nm and a relatively weak red emission at 664 nm, a simple, fast, and multicolor information encryption strategy was developed using IFE. First, the hydrophilic aUCNPs were obtained by modifying Tween 20 through the hydrophobic effect (Figures S5 and S6).…”

Multifaceted luminescence in lanthanide-activated microrods for advanced multicolor anti-counterfeiting

“…Lanthanide-doped materials exhibit excellent luminescent properties through various energy conversion mechanisms, giving rise to luminescence effects such as upconversion, downshifting, and afterglow. [23][24][25][26][27][28] While current research is mainly focused on upconversion and downshift luminescence based on lanthanide ions, [29][30][31][32][33][34] recent studies have also shown great interest in developing afterglow luminescence for information encryption and anti-counterfeiting, enhancing information security luminescence for information encryption and anticounterfeiting to further enhance the information security. [35][36][37][38][39] Distinct from photoluminescence, afterglow luminescence operates without real-time excitation, thus mitigating background noise interference.…”

Energy Migration Layer Modulated Lanthanide Luminescent Nanoparticles Toward Multimode Ratio Fluorescence Thermometers

“…In recent years, lanthanide-doped nanoparticles have attracted a lot of attention in many fields due to their high photostability, low cytotoxicity, long luminescence lifetime, and weak background noise. [1][2][3][4][5][6] Benefiting from the special electronic structure of lanthanide, they are able to achieve both upconversion and downshifting emission under the same wavelength excitation, thus covering a broad spectral emission region from ultraviolet to near-infrared (NIR). These rich emission bands are regarded as DOI: 10.1002/adom.202302880 a prerequisite for modulating the luminescent properties of the material, [7][8][9] which has always been a primary focus of fluorescence technology.…”