Ultraviolet ZnSe₁-xSx gradient-alloyed nanocrystals via a noninjection approach.
Highly emissive ultraviolet ZnSeS nanocrystals (NCs), with a core-shell-like structure, were designed and synthesized via a one-step noninjection approach in 1-octadecene (ODE). These ultraviolet ZnSeS NCs exhibit bright bandgap emission with high color purity and little trap emission. With full width at half-maximum (fwhm) of ∼21 nm only, photoluminescent (PL) quantum yield (QY) of ∼60% was estimated for one ensemble dispersed in toluene exhibiting bandgap absorption peaking at ∼380 nm and bandgap emission at ∼389 nm. These alloyed ZnSeS NCs present a cubic crystal structure consisting of a Se-rich core and a S-rich shell. Such a gradiently alloyed structure was suggested by our investigation on the temporal evolution of optical properties of the growing ZnSeS NCs monitored from 80 to 300 °C, together with structural and compositional characterization performed with XRD, XPS, EDX, and TEM. This newly developed one-step noninjection approach was achieved with zinc oleate (Zn(OA)(2)), diphenylphosphine selenide (SeDPP), and diphenylphosphine sulfide (SDPP) as Zn, Se, and S precursors, respectively. ZnSe monomers mainly participated in nucleation at ∼120 °C, while both ZnSe and ZnS monomers contributed to NC formation in later growth stages (∼160 °C and higher). (31)P NMR study demonstrates that SeDPP is more reactive than SDPP toward Zn(OA)(2), and also supports such a model proposed on the combination of ZnSe and ZnS monomers leading to nucleation/growth of ZnSeS alloyed NCs. The present study offers conceptual methodology to various highly photoluminescent alloyed NCs with high quality, high particle yield, and high synthetic reproducibility.
Steacie Institute for Molecular Sciences, National Research Council of Canada , Ottawa, Ontario K1A 0R6, Canada. kui.yu@nrc.ca
Kui
K
Yu
Amy
A
Hrdina
Jianying
J
Ouyang
David
D
Kingston
Xiaohua
X
Wu
Donald M
DM
Leek
Xiangyang
X
Liu
Chunsheng
C
Li
D000497:Alloys; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D053768:Metal Nanoparticles / Q000737:chemistry; D008956:Models, Chemical; D053758:Nanoparticles; D036103:Nanotechnology / Q000379:methods*; D010777:Photochemistry / Q000379:methods; D011208:Powders; D045663:Quantum Dots; D015203:Reproducibility of Results; D012643:Selenium / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013997:Time Factors; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
D000497:Alloys; D011208:Powders; D018036:Selenium Compounds; D017967:Zinc Compounds; D012643:Selenium; D015032:Zinc; C044696:zinc selenide