Dimensionality matters: dimensionality effects on the opto-electronic properties of semiconductor nanorods

Uri Banin, Institute of Chemistry and the Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, Israel

Studying the transition of properties of nanostructures as they develop from the zero-dimensional to the one-dimensional regime is significant for unravelling the modifications that occur in the electronic structure of the nanocrystal as its length to width aspect ratio is increased. Such understanding can lead to better design and control of the particle properties, with relevance for a wide range of technological applications. The ongoing improvements in the control of shape and morphology of nanocrystals in colloidal synthesis, which allows forming structures of similar composition but of different dimensionalities and shapes, open the way for probing such dimensionality effects, in particular by employing single particle microscopy and spectroscopy techniques using both far field and near field optical microscopy methods.

We will discuss several effects involving the 0D to 1D transition in CdSe/CdS core/shell nano heterostructures of different morphologies including “sphere in a sphere”, “sphere in a rod” and “rod in a rod”, using single particle based measurements to decipher these effects. The first dimensionality related aspect involves the modification of emission and absorption polarizations, as the dimensionality of the particles and of their cores changes. The second aspect relates to the function of these nanocrystals as donors in energy transfer processes to multiple dye molecules bound on their surfaces and functioning as acceptors. We will show how the dimensionality of the particles’ core and shell affects the donor’s time dependent survival probability, as well as the behavior of fluorescence resonant energy transfer (FRET) to multiple acceptors on single particle level. The opportunity to tailor the systems dimensionality with multiple acceptors on the surface results in enhanced FRET efficiencies with relevance for optical, sensing and energy funneling applications.