期刊
NANO LETTERS
卷 18, 期 2, 页码 709-716出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b03703
关键词
Indium phosphide; blinking; chemical structure; cadmium-free; zinc selenide; core-shell quantum dots
类别
资金
- National Science Foundation CHE [1506587]
- National Science Foundation EPS [1004083]
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [T32GM065086] Funding Source: NIH RePORTER
Thick-shell (>5 nm) InP-ZnSe colloidal quantum dots (QDs) grown by a continuous-injection shell growth process are reported. The growth of a thick crystalline shell is attributed to the high temperature of the growth process and the relatively low lattice mismatch between the InP core and ZnSe shell. In addition to a narrow ensemble photoluminescence (PL) line-width (similar to 40 nm), ensemble and single-particle emission dynamics measurements indicate that blinking and Auger recombination are reduced in these heterostructures. More specifically, high single-dot ON-times (>95%) were obtained for the core-shell QDs, and measured ensemble biexciton lifetimes, tau(2x) similar to 540 ps, represent a 7-fold increase compared to InP-ZnS QDs. Further, high-resolution energy dispersive X-ray (EDX) chemical maps directly show for the first time significant incorporation of indium into the shell of the InP-ZnSe QDs. Examination of the atomic structure of the thick-shell QDs by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) reveals structural defects in subpopulations of particles that may mitigate PL efficiencies (similar to 40% in ensemble), providing insight toward further synthetic refinement. These InP-ZnSe heterostructures represent progress toward fully cadmium-free QDs with superior photophysical properties important in biological labeling and other emission-based technologies.
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