Seed-mediated growth of shape-controlled wurtzite CdSe nanocrystals
Seed-mediated growth of shape-controlled wurtzite CdSe nanocrystals: Platelets, cubes, and rods Katherine P. Rice,† Aaron E. Saunders, and Mark P. Stoykovich* Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309 (USA) *To whom correspondence should be addressed. Phone: 303-492-6522. Fax: 303-492-4341. E-mail: [email protected] †
Present address:
Materials Reliability Division, National Institute of Standards and Technology,
Boulder, CO 80305 (USA)
Supporting Information CdSe seed particles Spherical CdSe seed particles were synthesized using a method based on that by Manna and coworkers (Carbone et al., Nano Lett. 2007, 7, 2942-2950), and characterized by UV-vis absorbance spectroscopy and TEM (Fig. S1).
Figure S1. (a) Optical absorbance spectra for small (blue), medium (red) and large (green) CdSe seeds. (b) TEM image of the medium-sized seeds with diameters of ~3 nm. S1
Bullet-shaped nanocrystals The synthesis of rod- and bullet-shaped CdSe nanocrystals can also be achieved using a seed growth mechanism. These morphologies grow in similar ways, with the bullets having an elongated but tapered shape. Figure S2 shows a series of bullet-shaped particles of varying diameters and aspect ratios. High-resolution TEM (Fig. S2b) of bullet nanocrystals confirms the wurtzite crystal structure throughout. We propose that the bullet-shaped CdSe particles grow similarly to the rods, but have a higher growth rate on the (00-2) face than on the (002) face that causes tapering along the length.
Figure S2. (a) TEM images of predominantly bullet-shaped CdSe nanocrystals. (b) HRTEM of the tapered particle.
S2
Distribution of nanocrystal dimensions Figure S3 shows the complete distribution of aspect ratios for CdSe nanocrystals synthesized with rod, cube, and hexagonal shapes.
Figure S3. Distribution of aspect ratios for the major shapes that were synthesized.
S3
Present address:
Materials Reliability Division, National Institute of Standards and Technology,
Boulder, CO 80305 (USA)
Supporting Information CdSe seed particles Spherical CdSe seed particles were synthesized using a method based on that by Manna and coworkers (Carbone et al., Nano Lett. 2007, 7, 2942-2950), and characterized by UV-vis absorbance spectroscopy and TEM (Fig. S1).
Figure S1. (a) Optical absorbance spectra for small (blue), medium (red) and large (green) CdSe seeds. (b) TEM image of the medium-sized seeds with diameters of ~3 nm. S1
Bullet-shaped nanocrystals The synthesis of rod- and bullet-shaped CdSe nanocrystals can also be achieved using a seed growth mechanism. These morphologies grow in similar ways, with the bullets having an elongated but tapered shape. Figure S2 shows a series of bullet-shaped particles of varying diameters and aspect ratios. High-resolution TEM (Fig. S2b) of bullet nanocrystals confirms the wurtzite crystal structure throughout. We propose that the bullet-shaped CdSe particles grow similarly to the rods, but have a higher growth rate on the (00-2) face than on the (002) face that causes tapering along the length.
Figure S2. (a) TEM images of predominantly bullet-shaped CdSe nanocrystals. (b) HRTEM of the tapered particle.
S2
Distribution of nanocrystal dimensions Figure S3 shows the complete distribution of aspect ratios for CdSe nanocrystals synthesized with rod, cube, and hexagonal shapes.
Figure S3. Distribution of aspect ratios for the major shapes that were synthesized.
S3
