Engineering

Crystal (programming language)

Materials science

Chromatography

Nanocomposite

Computer science

Chemical engineering

Photon upconversion

Laser

Physics

Nanotechnology

Organic chemistry

Crystallization

Microsphere

Optics

Doping

Luminescence

Photothermal therapy

Analytical Chemistry (journal)

Nanocrystal

Chemistry

Programming language

Lanthanide

Optoelectronics

Glass microsphere

Chemical Engineering Journal

Currently, advanced security strategies have aroused widely interest in anti-counterfeiting field to ensure the authentic items difficult to be replicated. Herein, cubic Cs3LnF6 (Ln = Y, Yb, Lu, Sc) nanocrystals embedded glasses are successfully prepared via an in-situ glass crystallization strategy. Emitting centers, such as Eu3+, Er3+, Ho3+ and Tm3+, can be incorporated into the precipitated Cs3YF6, Cs3YbF6 and Cs3LuF6 crystal lattices but remain in glass matrix rather than in Cs3ScF6 crystals for large ionic radius mismatch between lanthanide activators and Sc3+ host ions. It is demonstrated that upconverting quantum yields of all the Yb/Er: Cs3LnF6@glass samples are higher than those of well-known cubic/hexagonal Yb/Er: α/β-NaYF4@glass samples. Specifically, Yb/Er: Cs3LuF6@glass exhibits a maximal quantum yield of ~0.30%, which is superior to Yb/Er: β-NaYF4 @glass (~0.19%). Impressively, Er: Cs3YbF6@glass shows a remarkable 980 nm laser-induced photothermal effect, leading to significant alteration of upconversion emissive color from red to green with increase of incident laser power. As a prototype of the concept for practical application, a series of luminescent patterns using Er: Cs3YbF6@glass upconverting inks are constructed by a screen-printing technique and show distinct laser-power-sensitive emissive colors, being feasible for high-level anti-counterfeiting. The present work exploits a new anti-counterfeiting strategy by developing highly efficient laser-induced upconverting photothermal materials.

Remarkable laser-driven upconverting photothermal effect of Cs3LnF6@glass nanocomposites for anti-counterfeiting