Broken Band Alignment in EuS-CdS Nanoheterostructures

Integration of multiple materials in a controllably programmed manner on the nanoscale has led to the evolution of the next generation of nanoparticles. We have explored the formation of bifunctional europium sulfide − cadmium chalcogenide composite nanostructures, as both of the semiconductor materials exhibit intriguing physical characteristics, suggesting that architectural tunability of these hybrid structures could have interesting effects on their collective properties. A two step synthetic procedure has been devised, where CdSe or CdS nanorods were used as a platform for the growth of the secondary material domains. An eight-coordinate lanthanide based single-source precursor, Eu(Ddtc)3(Bipy), was implemented as the material source for the selective growth of spherical EuS nanocrystals on the tips of cadmium chalcogenide nanorods. The composition and structure of these hybrid particles have been analyzed by high-resolution TEM. The nanoheterostrucutre has a type III, or broken band alignment, which has led to the quenching of the luminescence of the initial cadmium chalcogenide nanorods following the growth of EuS tips and the formation of the interfacial heterojunction.