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Upconversion Dynamics in Er 3+ ‐Doped Gd 2 O 2 S: Influence of Excitation Power, Er 3+ Concentration, and Defects
Author(s) -
MartínRodríguez Rosa,
Rabouw Freddy T.,
Trevisani Mattia,
Bettinelli Marco,
Meijerink Andries
Publication year - 2015
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201400588
Subject(s) - photon upconversion , materials science , luminescence , excitation , analytical chemistry (journal) , atomic physics , doping , quenching (fluorescence) , annihilation , quantum yield , optoelectronics , physics , fluorescence , optics , chemistry , chromatography , quantum mechanics
Upconversion (UC) enables the conversion of lower energy to higher energy photons and has gained interest for the application in solar cells and nanocrystal biolabels. Er 3+ ‐doped Gd 2 O 2 S is a highly promising UC material for applications. A record UC quantum yield of 12% was recently measured in Gd 2 O 2 S doped with 10% Er 3+ upon monochromatic excitation into the 4 I 13/2 state at 1510 nm for moderate excitation densities (700 W m −2 ). In this work, the focus is on the dynamics of the infrared ( 4 I 13/2 , ≈1500 nm) to near‐infrared ( 4 I 11/2 , ≈1000 nm) UC luminescence in Er 3+ ‐doped Gd 2 O 2 S. On the basis of luminescence spectra (emission and excitation), UC emission decay curves, and rate equation modeling, it is shown that energy transfer upconversion (ETU) is the mechanism responsible for the 4 I 11/2 UC luminescence, and the ETU parameter for Gd 2 O 2 S:10%Er 3+ is determined to be W ETU = 6.3 × 10 −19 cm 3 s −1 . The UC dynamics depend on the Er 3+ concentration and, similar to triplet–triplet annihilation UC in organic materials, on the excitation power. The results highlight the subtle balance between desired energy transfer processes leading to ETU and undesired energy migration to quenching sites. The overall UC efficiency is dependent not only on the material and composition but also on the synthesis process.