Direct Evidence for Coupled Surface and Concentration Quenching Dynamics in Lanthanide-Doped Nanocrystals.
Luminescence quenching at high dopant concentrations generally limits the dopant concentration to less than 1-5 mol% in lanthanide-doped materials, and this remains a major obstacle in designing materials with enhanced efficiency/brightness. In this work, we provide direct evidence that the major quenching process at high dopant concentrations is the energy migration to the surface (i.e., surface quenching) as opposed to the common misconception of cross-relaxation between dopant ions. We show that after an inert epitaxial shell growth, erbium (Er3+) concentrations as high as 100 mol% in NaY(Er)F4/NaLuF4core/shell nanocrystals enhance the emission intensity of both upconversion and downshifted luminescence across different excitation wavelengths (980, 800, and 658 nm), with negligible concentration quenching effects. Our results highlight the strong coupling of concentration and surface quenching effects in colloidal lanthanide-doped nanocrystals, and that inert epitaxial shell growth can overcome concentration quenching. These fundamental insights into the photophysical processes in heavily doped nanocrystals will give rise to enhanced properties not previously thought possible with compositions optimized in bulk.
Noah J J
0000-0002-0721-3186
NJ
Johnson
Sha
S
He
Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Shuo
S
Diao
The Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Emory M
EM
Chan
Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Hongjie
H
Dai
Adah
0000-0001-5339-0207
A
Almutairi
D028581:Lanthanoid Series Elements / Q000737:chemistry*; D049449:Luminescence; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013816:Thermodynamics
D028581:Lanthanoid Series Elements