Ultraviolet ZnSe1鈥?i>xSx Gradient-Alloyed Nanocrystals via a Noninjection Approach
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- 作者：Kui Yu ; Amy Hrdina ; Jianying Ouyang ; David Kingston ; Xiaohua Wu ; Donald M. Leek ; Xiangyang Liu ; Chunsheng Li
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2012
- 出版时间：August 22, 2012
- 年：2012
- 卷：4
- 期：8
- 页码：4302-4311
- 全文大小：682K
- 年卷期：v.4,no.8(August 22, 2012)
- ISSN：1944-8252
文摘
Highly emissive ultraviolet ZnSeS nanocrystals (NCs), with a core鈥搒hell-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 掳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 掳C, while both ZnSe and ZnS monomers contributed to NC formation in later growth stages (160 掳C and higher). 31P 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.