Gradiently Alloyed ZnxCd1-xS Colloidal Photoluminescent Quantum Dots Synthesized via a Noninjection One-Pot Approach

High-quality colloidal photoluminescent (PL) ZnCdS quantum dots (QDs) with gradient distribution of components, consisting of Cd-rich inner cores and Zn-rich outer shells, were synthesized via a noninjection one-pot approach. This newly developed synthetic approach uses zinc stearate (Zn(St)2), cadmium acetate dihydrate (Cd(OAc)2·2H2O), and elemental sulfur as Zn, Cd, and S source compounds, respectively. The growth of the cubic-structured QDs was carried out at 240 °C in a reaction flask consisting of the source compounds, together with stearic acid (SA), 2,2‘-dithiobisbenzothiazole (MBTS), and 1-octadecene (ODE); all of these chemicals were loaded at room temperature. The temporal evolution of the optical properties of the growing QDs, including absorption and photoemission, was monitored in detail; the evolution monitored indicates that the growth kinetics, the composition, and the distribution of the Zn and Cd in the resulting ternary ZnxCd1-xS QDs are sensitive to feed Zn−Cd−S molar ratios. Detailed ...

[1]  Alf Mews,et al.  Synthesis and characterization of highly luminescent CdSe-core CdS/Zn0.5Cd0.5S/ZnS multishell nanocrystals. , 2005, Journal of the American Chemical Society.

[2]  Cristina Badarau,et al.  Solid state NMR studies of photoluminescent cadmium chalcogenide nanoparticles. , 2006, Physical chemistry chemical physics : PCCP.

[3]  A. P. Alivisatos,et al.  Epitaxial growth and photochemical annealing of graded CdS/ZnS shells on colloidal CdSe nanorods. , 2002, Journal of the American Chemical Society.

[4]  S. Gambhir,et al.  Quantum Dots for Live Cells, in Vivo Imaging, and Diagnostics , 2005, Science.

[5]  Excitonic effects and optical properties of passivated CdSe clusters. , 2006, Physical review letters.

[6]  W. Knoll,et al.  Embryonic Nuclei-Induced Alloying Process for the Reproducible Synthesis of Blue-Emitting ZnxCd1-xSe Nanocrystals with Long-Time Thermal Stability in Size Distribution and Emission Wavelength , 2004 .

[7]  Y. C. Cao,et al.  One-pot synthesis of high-quality zinc-blende CdS nanocrystals. , 2004, Journal of the American Chemical Society.

[8]  Xiaogang Peng,et al.  Formation of high-quality CdS and other II-VI semiconductor nanocrystals in noncoordinating solvents: tunable reactivity of monomers. , 2002, Angewandte Chemie.

[9]  M. S. El-shall,et al.  Room-Temperature Synthesis and Characterization of Nanocrystalline CdS, ZnS, and CdxZn1-xS , 2002 .

[10]  Wolfgang Knoll,et al.  Composition-tunable Zn(x)Cd(1-x)Se nanocrystals with high luminescence and stability. , 2003, Journal of the American Chemical Society.

[11]  Jacek K. Furdyna,et al.  Diluted magnetic semiconductors , 1988 .

[12]  P. Mulvaney,et al.  From Cd-rich to se-rich--the manipulation of CdSe nanocrystal surface stoichiometry. , 2007, Journal of the American Chemical Society.

[13]  Xiaogang Peng,et al.  Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals , 2003 .

[14]  Wei Chen,et al.  Upconversion Luminescence of Colloidal CdS and ZnCdS Semiconductor Quantum Dots , 2007 .

[15]  L. Feldman,et al.  Homogeneously alloyed CdSxSe1-x nanocrystals: synthesis, characterization, and composition/size-dependent band gap. , 2006, Journal of the American Chemical Society.

[16]  W. Knoll,et al.  Synthesis of high-quality CdS, ZnS, and ZnxCd1-xS nanocrystals using metal salts and elemental sulfur , 2004 .

[17]  Royce W Murray,et al.  Ligand effects on optical properties of CdSe nanocrystals. , 2005, The journal of physical chemistry. B.

[18]  Yongan Yang,et al.  Synthesis of CdSe and CdTe nanocrystals without precursor injection. , 2005, Angewandte Chemie.

[19]  L. Pu,et al.  High quality CdSeS nanocrystals synthesized by facile single injection process and their electroluminescence. , 2003, Chemical communications.

[20]  Xiaogang Peng,et al.  Formation of high-quality CdTe, CdSe, and CdS nanocrystals using CdO as precursor. , 2001, Journal of the American Chemical Society.

[21]  Wolfgang Knoll,et al.  Alloyed Zn(x)Cd(1-x)S nanocrystals with highly narrow luminescence spectral width. , 2003, Journal of the American Chemical Society.

[22]  M. Bawendi,et al.  Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystallites , 1993 .

[23]  J. Ripmeester,et al.  Colloidal CdSe nanocrystals from tri-n-octylphosphine: Part II: control of growth rate for high quality and large-scale production by tuning Cd-to-Se stoichiometry. , 2005, Journal of nanoscience and nanotechnology.

[24]  John A. Ripmeester,et al.  The Effect of Dispersion Media on Photoluminescence of Colloidal CdSe Nanocrystals Synthesized from TOP , 2005 .

[25]  Virginia Chu,et al.  Effect of reaction media on the growth and photoluminescence of colloidal CdSe nanocrystals. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[26]  S. Nie,et al.  Quantum dot bioconjugates for ultrasensitive nonisotopic detection. , 1998, Science.

[27]  I. Kokanović,et al.  Structure and crystallization of the partially crystalline Zr76Ni24 metallic glass , 2004 .

[28]  A. D. Yoffe,et al.  Low-dimensional systems: Quantum size effects and electronic properties of semiconductor microcrystallites (zero-dimensional systems) and some quasi-two-dimensional systems , 1993 .

[29]  J. Ripmeester,et al.  Colloidal CdSe nanocrystals from tri-n-octylphosphine: Part 1: growth and optical properties from polar and non-polar solvents. , 2005, Journal of nanoscience and nanotechnology.

[30]  L. Vegard,et al.  Die Konstitution der Mischkristalle und die Raumfüllung der Atome , 1921 .

[31]  A. Alivisatos.  Semiconductor Clusters, Nanocrystals, and Quantum Dots , 1996, Science.

[32]  M. Bawendi,et al.  (CdSe)ZnS Core-Shell Quantum Dots - Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites , 1997 .

[33]  T. Mallouk,et al.  Demonstration of a shell-core structure in layered cadmium selenide-zinc selenide small particles by x-ray photoelectron and Auger spectroscopies , 1992 .

[34]  R. Ahlrichs,et al.  Cadmium selenide semiconductor nanocrystals: a theoretical study , 1998 .

[35]  Horst Weller,et al.  Photochemistry of colloidal semiconductors. 20. Surface modification and stability of strong luminescing CdS particles , 1987 .

[36]  Vladimir Bulovic,et al.  Tuning the performance of hybrid organic/inorganic quantum dot light-emitting devices , 2003 .

[37]  Igor L. Medintz,et al.  Quantum dot bioconjugates for imaging, labelling and sensing , 2005, Nature materials.

[38]  Tobias Vossmeyer,et al.  CdS Nanoclusters: Synthesis, Characterization, Size Dependent Oscillator Strength, Temperature Shift of the Excitonic Transition Energy, and Reversible Absorbance Shift , 1994 .

[39]  Xiaogang Peng.  Green chemical approaches toward high-quality semiconductor nanocrystals. , 2002, Chemistry.

[40]  S. Bass,et al.  Constituent quarks and g1 , 1999, hep-ph/9902280.

[41]  D. F. Eaton,et al.  International Union of Pure and Applied Chemistry Organic Chemistry Division Commission on Photochemistry. Reference materials for fluorescence measurement. , 1988, Journal of photochemistry and photobiology. B, Biology.

[42]  Shuming Nie,et al.  Alloyed semiconductor quantum dots: tuning the optical properties without changing the particle size. , 2003, Journal of the American Chemical Society.

[43]  R. Friesner,et al.  Quantum confinement effects in semiconductor clusters , 1991 .