Strain-Induced Modification of Optical Selection Rules in Lanthanide-Based Upconverting Nanoparticles

Abstract

NaYF4:Yb(3+),Er(3+) nanoparticle upconverters are hindered by low quantum efficiencies arising in large part from the parity-forbidden nature of their optical transitions and the nonoptimal spatial separations between lanthanide ions. Here, we use pressure-induced lattice distortion to systematically modify both parameters. Although hexagonal-phase nanoparticles exhibit a monotonic decrease in upconversion emission, cubic-phase particles experience a nearly 2-fold increase in efficiency. In-situ X-ray diffraction indicates that these emission changes require only a 1% reduction in lattice constant. Our work highlights the intricate relationship between upconversion efficiency and lattice geometry and provides a promising approach to modifying the quantum efficiency of any lanthanide upconverter.

Concentration-Dominated Temperature-Dependence of Upconversion Luminescence in Gd6WO12 Nanophosphor Co-Doped with Er3+ and Yb3+

“…17 Previous investigations have formed a well-known consensus that Er 3+ /Yb 3+ co-doped fluorides such as NaYF 4 :Er 3+ /Yb 3+ and NaLuF 4 :Er 3+ /Yb 3+ exhibited the highest UC luminescence yields. [18][19][20] However, these fluoride materials usually require relatively completed preparative procedures. In addition, their stability is worse than that of oxides.…”

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

“…Direct demonstration of the influence of the crystal lattice properties on UC luminescence can be realized in-situ and real-time by using a physical approach. 174 . By placing α-and β-phase NaYF 4 :Yb/Er co-doped UCNPs in a diamond anvil cell they could be subjected to pressures as high as 25 GPa.…”

“…The above examples of physically manipulating lattice properties enable modulation of the UCL which can be reversible up to the damage threshold 173,174 , which is not applicable in the case of chemical host lattice manipulation. It can thus provide additional insights into brightness enhancements caused by nuanced crystal field asymmetries.…”

Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

“…The low emission intensity of RE-based NPs constitute a serious limitation for most of the applications of these materials [198], and many different strategies have been employed in the literature to overcome this disadvantage. This is especially severe in UCNPs [199], in which quantum yield values range from 0.005% to 0.3% in NaYF 4 :Er 3+ , Yb 3+ NPs [190].…”