Radiative Recombination Of Spatially Extended Excitons In (znse/cds)/cds Heterostructured Nanorods

We report on organometallic synthesis of luminescent (ZnSe/CdS)/CdS semiconductor heterostructured nanorods (hetero-NRs) that produce an efficient spatial separation of carriers along the main axis of the structure (type II carrier localization). Nanorods were fabricated using a seeded-type approach by nucleating the growth of 20-100 nm CdS extensions at [000 +/- 1] facets of wurtzite ZnSe/CdS core/shell nanocrystals. The difference in growth rates of CdS in each of the two directions ensures that the position of ZnSe/CdS seeds in the final structure is offset from the center of hetero-NRs, resulting in a spatially asymmetric distribution of carrier wave functions along the heterostructure. Present work demonstrates a number of unique properties of (ZnSe/CdS)/CdS hetero-NRs, including enhanced magnitude of quantum confined Stark effect and subnanosecond switching of absorption energies that can find practical applications in electroabsorption switches and ultrasensitive charge detectors

The Effect of Dielectric Friction on the Rate of Charge Separation in Type Ii Znse/Cds Semiconductor Nanorods

The effect of dielectric friction on the rate of charge separation in type II ZnSe/CdS semiconductor nanorods has been investigated using picosecond transient absorption spectroscopy. The spatial separation of an excited electron-hole pair was estimated from the redshift in band edge absorption corresponding to the decrease in the exciton binding energy. The present study identifies a considerable effect of the solvent polarity on the rate of charge separation in semiconductor heterostructures, which should be taken into account when selecting nanorod caging media, such as solvents or polymer matrices. © 2009 American Institute of Physics