Optical Analysis of a series of Size and Shape-controlled Type-II CdTe/CdSe/CdTe Heterostructure Nanorods

Two series of size and shape-controlled type-II CdTe/CdSe/CdTe heterostructure nanorods with different geometrical structures were prepared by the colloidal sequential reactant injection technique. The samples, including pure CdSe seeds, were optically analysed by steady state and time resolved photoluminescence spectra. The experimental results demonstrate that the energy and lifetime of the photoluminescence from charge-separated band structure can be tuned by the nature of nanorods' band edges in both "linear" and "core-shell" heterostructure nanorods. But between different groups of nanorod samples, the spectral properties show different variation tendencies with the increasing CdTe tip. As one possible explanation, the compensation between the variations of kinetic and Coulomb contributions was discussed by numerical calculations based on the effective mass and envelope function approximations.