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Ultrasmall Pb:Ag 2 S Quantum Dots with Uniform Particle Size and Bright Tunable Fluorescence in the NIR‐II Window
Author(s) -
He He,
Lin Yi,
Tian ZhiQuan,
Zhu DongLiang,
Zhang ZhiLing,
Pang DaiWen
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201703296
Subject(s) - quantum dot , fluorescence , particle size , window (computing) , materials science , particle (ecology) , nanotechnology , optoelectronics , optics , physics , chemistry , computer science , oceanography , geology , operating system
Ag 2 S quantum dots (QDs) are well‐known near‐infrared fluorophores and have attracted great interest in biomedical labeling and imaging in the past years. However, their photoluminescence efficiency is hard to compete with Cd‐, Pb‐based QDs. The high Ag + mobility in Ag 2 S crystal, which causes plenty of cation deficiency and crystal defects, may be responsible mainly for the low photoluminescence quantum yield (PLQY) of Ag 2 S QDs. Herein, a cation‐doping strategy is presented via introducing a certain dosage of transition metal Pb 2+ ions into Ag 2 S nanocrystals to mitigate this intrinsic shortcoming. The Pb‐doped Ag 2 S QDs (designated as Pb:Ag 2 S QDs) present a renovated crystal structure and significantly enhanced optical performance. Moreover, by simply adjusting the levels of Pb doping in the doped nanocrystals, Pb:Ag 2 S QDs with bright emission (PLQY up to 30.2%) from 975 to 1242 nm can be prepared without altering the ultrasmall particle size (≈2.7–2.8 nm). Evidently, this cation‐doping strategy facilitates both the renovation of crystal structure of Ag 2 S QDs and modulation of their optical properties.