Wydział Chemii

Weichang Li

Lili Hu

Wei Chen

Shiyu Sun

Małgorzata Guzik

Georges Boulon

2022

Journal of Alloys and Compounds

926

166743/1-166743/12

10.1016/j.jallcom.2022.166743

Naukowa

Angielski

Artykuł

Pure red fluorescence generated by near infrared (NIR) excitation is desired for bio-imaging with high biological penetration, but without cell damage or multi-photon photo-toxicity. In this work, β-NaYF₄:Er³⁺ and β-NaYF₄:Er³⁺,Tm³⁺ microcrystals were synthesized using a novel hydrothermal method. β-NaYF₄:Er³⁺ microcrystals exhibited intense green and red up-conversion emissions under 976 nm laser diode excitation. The introduction of Tm³⁺ ions into β-NaYF₄:Er³⁺ resulted in strong inhibition of green up-conversion emission (Er³⁺:²H_11/2 /⁴S_3/2→⁴I_15/2) and, consequently, red up-conversion emission (Er³⁺:⁴F_9/2→⁴I_15/2) was significantly promoted. To simultaneously restrain green up-conversion emissions and enhance red up-conversion emissions, the optimal concentrations of Er³⁺ and Tm³⁺ ions were determined to be 20 mol% and 2.0 mol%, respectively. The red/green up-conversion emission intensity ratio increased from ~1.80 (β-NaYF₄:20Er³⁺, mol%) to ~78 (β-NaYF₄:20Er³⁺,2Tm³⁺, mol%) after the addition of 2 mol% Tm³⁺ ions to β-NaYF₄:20Er³⁺ (mol%). The red up-conversion emission intensity of β-NaYF₄:20Er³⁺,2Tm³⁺ was stronger than that for commercial red up-conversion phosphors (NaYF₄ and ZnF₂) under the same experimental conditions. Based on the results of the emission spectra, luminescence rise, and decay profiles, the mechanism of enhanced red up-conversion emission by Tm³⁺ ion co-doping in β-NaYF₄:20Er³⁺,2Tm³⁺ (mol%) was proposed. The bio-fluorescence experiment under NIR excitation proves that β-NaYF₄:Er³⁺,Tm³⁺ microcrystals have potential applications in bio-imaging.

β-NaYF4:Er3+ and β-NaYF4:Er3+, Tm3+ micro-crystals, Green and red up-conversion emissions, Tm3+ energy trapping center, Hydrothermal method, Energy transfer

http://dx.doi.org/10.1016/j.jallcom.2022.166743

http://www.elsevier.com