A Safer, Easier, Faster Synthesis for CdSe Quantum Dot Nanocrystals

Abstract

Properties that vary with particle size are an important feature of nanoscale materials. CdSe quantum dot nanocrystals vary in color from green–yellow to orange–red and luminesce from blue to yellow, where shorter wavelength, higher energy, electronic transitions correspond to smaller particle sizes. CdSe quantum dot nanocrystals are a visually engaging way to demonstrate quantum effects in chemistry, since their transition energies can be explained as a "particle in a box", where a delocalized electron is the particle and the nanocrystal is the box. Following the method pioneered by Xiaogang Peng and coworkers, CdSe nanocrystals are synthesized from CdO, oleic acid, elemental Se, and trioctylphosphine using a kinetic growth method in octadecene at 225 °C and a less than three-minute reaction time. This synthesis has several advantages over methods using dimethyl cadmium, a chemical that is extremely toxic, expensive, unstable, pyrophoric, and requires inert atmosphere techniques. When excited at 400 nm, the colloidal suspensions of quantum dots give relatively sharp emission spectra with ∼35-nm peak widths, indicating monodisperse particle sizes. Corresponding absorbance spectra are also of high quality.

Semiconductor II-VI Quantum Dots with Interface States and Their Biomedical Applications

“…QDs have been reported (Crouch et al, 2003;Heine et al, 1998;Lou et al, 2004;Murray et al, 1993;Murray et al, 2000;Murray et al, 2001;Nordell et al, 2005;Park et al, 2004;Rosenthal et al, 2007;Yoon et al, 2005;Yu et al, 2005). The essential elements of these methods involve appropriate metallic or organometallic precursors (zinc, cadmium or mercury) with corresponding chalcogen precursors (sulfur, selenium or tellurium) in a coordinating solvent at high temperatures (Danek et al, 1994;Heine et al, 1998;Lou et al, 2004;Malik et al, 2005;Murray et al, 1993;Murray et al, 2000;Murray et al, 2001;Nann et al, 2002;Peng et al, 2001).…”

Advancing colloidal quantum dot photovoltaic technology

“…These compounds include binary, mostly III-V and II-VI semiconductors such as metal chalcogenides [78][79][80], as well as ternary and quaternary compounds [81][82][83][84].…”

Coherent phonons in CdSe quantum dots triggered by ultrafast electron transfer

“…For the synthesis of CdSe QDs we slightly modified a method introduced by Nordell et al [6]. The particles diameter of 3.1 nm was determined by the spectral position of the lowest excitonic transition (1S(e)-1S 3/2 (h)).…”