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Large Upconversion Enhancement in the “Islands” Au–Ag Alloy/NaYF 4 : Yb 3+ , Tm 3+ /Er 3+ Composite Films, and Fingerprint Identification
Author(s) -
Chen Xu,
Xu Wen,
Zhang Lihang,
Bai Xue,
Cui Shaobo,
Zhou Donglei,
Yin Ze,
Song Hongwei,
Kim DongHwan
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201502419
Subject(s) - materials science , photon upconversion , nanoparticle , analytical chemistry (journal) , excitation , metal , alloy , reflection (computer programming) , luminescence , optoelectronics , nanotechnology , composite material , metallurgy , physics , chemistry , chromatography , quantum mechanics , computer science , programming language
The surface plasmon (SP) modulation is a promised way to highly improve the strength of upconversion luminescence (UCL) and expand its applications. In this work, the “islands” Au–Ag alloy film is prepared by an organic removal template method and explored to improve the UCL of NaYF 4 : Yb3+, Tm 3+ /Er 3+ . After the optimization of Au–Ag molar ratio (Au 1.25 –Ag 0.625 ) and the size of NaYF 4 nanoparticles (NPs, ≈7 nm), an optimum enhancement as high as 180 folds is obtained (by reflection measurement) for the overall UCL intensity of Tm 3+ . Systematic studies indicate that the UCL enhancement factor (EF) increases with the increased size of metal NPs and the increase of diffuse reflection, with the decreased size of NaYF 4 NPs, with the decreased power density of excitation light and with improving order of multiphoton populating. The total decay rate varies only ranging of about 20% while EF changes significantly. All the facts above indicate that the UCL enhancement mainly originates from coupling of SP with the excitation electromagnetic field. Furthermore, the fingerprint identification based on SP‐enhanced UCL is realized in the metal/UC system, which provides a novel insight for the application of the metal/UC device.