Confinement on the energy transfer between luminescent centers in nanocrystals.

Journal Article · Sat Nov 01 00:00:00 EST 2003 · J. Appl. Phys.

DOI:https://doi.org/10.1063/1.1614865· OSTI ID:961262

Chen, X Y; Zhuang, H Z; Li, S; Niedbala, R S; Liu, G K

The luminescence dynamics of optical centers in nanocrystals depends critically on the phonon density of states (PDOS), which is quite distinct from that of bulk materials. It is shown that energy transfer (ET) in nanocrystals is confined by discrete PDOS as well as direct size restriction. Temperature-, concentration-, and size-dependence of the fluorescence decay from the {sup 4}S{sub 3/2} state of Er{sup 3+} in Y{sub 2}O{sub 2}S nanocrystals have been investigated using laser spectroscopic experiments and computational simulations. A set of microscopic rate equations that govern the evolution of the excitation probability P{sub i}(t) are solved iteratively using a Monte Carlo method. The simulations of ET based on a theoretical model with five parameters are in good agreement with the experimental results. It is shown that phonon-assisted ET processes in Er{sup 3+}:Y{sub 2}O{sub 2}S nanocrystals contribute partly to the fluorescence decay at 295 K, and is negligible at 5 K. For applications, the nanoconfinement effects on ET may significantly reduce the efficiency of sensitized or upconversion luminescence due to the lack of low-frequency phonon modes and restricted excitation migration in nanophosphors.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC02-06CH11357
• OSTI ID: 961262
• Report Number(s): ANL/CHM/JA-45877; JAPIAU; TRN: US1003426
• Journal Information: J. Appl. Phys., Vol. 94, Issue 9 ; Nov. 1, 2003; ISSN 0021-8979
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CONFINEMENT
CRYSTALS
DECAY
DENSITY
DYNAMICS
EFFICIENCY
ELECTRON-PHONON COUPLING
ENERGY TRANSFER
EQUATIONS
ERBIUM
EXCITATION
FLUORESCENCE
LASERS
LUMINESCENCE
MATERIALS
MIGRATION
MONTE CARLO METHOD
NANOSTRUCTURES
PHONONS
PROBABILITY
SIZE
USES
YTTRIUM COMPOUNDS