Cite this article: Manthiram, K., Beberwyck, B. J., Talapin, D. V., and Alivisatos, A. P.  Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

 J. Vis. Exp. (82), e50731, doi:10.3791/50731 (2013).

Here’s another guest blog post featuring a video article from JoVE (The Journal of Visualized Experiments). February’s article gives us insight into the fascinating world of tunable nanoparticles, a technology that enables the LED displays which have become commonplace in most of our TVs. Better mastery of these materials will lead to improved, brighter, and longer-lasting displays, so it’s fitting that the experiment is brought to you through the medium of video!  Do follow the link below to check it  out and as usual you can let us know what you think in the comments below.

By Val Buntrock, Ph.D.

Science Editor, JoVE

The rapidly growing nano field emerged from the interdisciplinary collaboration between the chemistry and physics communities. Sub-molecular particles display unique photophysical properties, including unusually high absorption extinction coefficients and fluorescent quantum yields, making them attractive materials for use in energy harvesting systems or optical display devices such as TV monitors.

Particle size and shape greatly influence the optical properties of nanoparticles. Learning how to modulate these features is ideal for optimizing application performance. Despite the immense amount of research focused on nano, precise synthetic control remains elusive, until now. A video article recently published in JoVE, Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals, demonstrates how to control the size and shape of cadmium selenium/cadmium sulfur, CdSe/CdS heterostructures, paving the way for more controlled nano syntheses and predictable optical properties.

The Alivisatos group is able to grow either nanorods or tetrapods of CdSe/CdS particles using a seeded synthetic approach and separating the nucleation and growth phases. In the initial seeding stage, the group prepares CdSe spheres in one flask. After confirming the size and crystallinity using scanning electron microscopy (SEM) and X-ray diffraction techniques (XRD), the CdSe spheres are transferred to a separate flask to serve as the seed where CdS is added to grow CdSe/CdS heterostructures.

Depending on the crystal form of the CdSe seed spheres, the Alivisatos group can grow the heterostructures to form nanorods or tetrapods. If the precursor CdSe sphere is a wurtzite phase, nanorods form, while a zinc-blende crystal phase promotes tetrapod growth. Both structures are confirmed using SEM and XRD.

As expected, the two different CdSe/CdS crystal shapes exhibit distinguishable absorbencies that are desirably enhanced relative to the starting CdSe spheres. In this video article, the Alivisatos group demonstrates that improved optical absorbencies can be obtained with skilled synthetic techniques. Further, every subtle nuance of this delicate preparation method is captured in JoVE video format, leaving no detail shadowed in condensed field-specific language, allowing both novices and experts to learn from and implement seeded nanoparticle syntheses in their own lab.

Tunable nanoparticles are especially desirable for a technology found in most American homes- bright light emitting diode (LED) television displays. The crucial preparation details presented in Alivisatos’ video article can be modified for a variety of materials, leading to improved displays with brighter colors and longer lifetimes. Come watch this method and many others on an LED TV by visiting the JoVE booth at the upcoming American Physical Society Conference (booth #635/734) and the American Chemical Society Meeting (booth #830) in March and learn more about nanoparticles and their larger compatriots, molecules.