Highly efficient La2O3: Yb3+, Tm3+ single-band NIR-to-NIR upconverting microcrystals for anti-counterfeiting applications.
2 November 2018
Efficient single-band NIR-to-NIR upconvrsion (UC) emission is strongly desired for many applications such as fluorescent markers, plastic recycling, and biological imaging. Herein, we report highly-efficient single-band NIR-to-NIR UC emission in La2O3:Yb3+,Tm3+ (LYT) microcrystals.
Under 980 nm laser excitation, LYT exhibits NIR UC emission at ~795 nm (Tm3+: 3H4 → 3H6), and blue UC emission at ~476 nm; the NIR UC emission is dominant, with the intensity ratio of the NIR to blue INIR/Iblue > 100. Remarkably, a high absolute UC quantum yield (UCQY) of 3.4 % is obtained for the single-band NIR UC emission of LYT at a relatively low excitation power density of 7.6 W/cm2.
This value is much higher than the reported values of a single-band NIR UC for rare earth based UC materials in literature, such as the well-known benchmark UC materials of ß-NaYF4:Yb3+,Er3+ (~0.9%, with a excitation power density of 9 W/cm2) and Gd2O2S:Yb3+,Er3+ (~1.9%, with a excitation power density of 20 W/cm2).
The high absolute UCQY of single-band NIR UC emission combined with their facile preparation hints at their potential application in anti-counterfeiting, verified by the proof-of-concept demonstration of fluorescent labeling of a transparent “IMT” pattern.
Gao, G., Busko, D., Joseph, R., Howard, I.A., Turshatov, A. and Richards, B.S., 2018. Highly efficient La2O3: Yb3+, Tm3+ single-band NIR-to-NIR upconverting microcrystals for anti-counterfeiting applications. ACS Applied Materials & Interfaces.
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Categories: Material & Chemical