期刊
MATERIALS RESEARCH EXPRESS
卷 6, 期 8, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/2053-1591/ab28b6
关键词
Al2O3 self-passivation layer; temperature-dependent PL; optical stability
资金
- National High Technology Research and Development Program of China (863Program) [2013AA014201]
- National Key Foundation for Exploring Scientific Instrument of China [2014YQ120351]
- Natural Science Foundation of Tianjin [15JCYBJC16700, 15JCYBJC16800, 17JCQNJC02300, 18JCYBJC86200]
- National Natural Science Foundation of China [11504266, 51702235]
Semiconductor quantum dots (QDs) have aroused extensive interest in various applications because of their excellent optical and electronic properties. However, long-term photostability of the CdSe QDs has always posed application challenges. This study discusses the high-quality QDs synthesized using an uncomplicated coating method. The ultrathin epitaxial Al self-passivation layer is coated with a homogeneous ligand to maintain high luminescent efficiency and photostability of the QDs. The time-dependent intensity responses of the CdSe/CdS, CdSe/CdS/Al, and CdSe/CdS/CdS/AlQDs were verified under continuous irradiation using a single-particle one-watt blue light-emitting diode (LED). The CdSe/CdS photoluminescence (PL) intensity rapidly decreased under the blue LED illumination, whereas that of the CdSe/CdS/CdS/AlQDs remained almost unchanged for 300 min. The PL spectra of the three samples in 10-300 K were verified by comparing the temperature-dependent full-width at half-maximum of their emission energies and luminescent intensities. The mechanism of the temperature-dependent non-radiative relaxation of CdSe QDs coated with CdS layers of different thicknesses evolved from the thermal activation of carrier trapping by surface defects/traps in the CdSe QDs to the thermal escape of carriers in the core/shell QDs, assisted by multiple longitudinal-optical phonons. The luminescence mechanism was almost independent of the Al epitaxial growth layer.
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