Mobility and Spatial Distribution of Photoexcited Electrons in CdSe/CdS Nanorods

The mobility and spatial distribution of photoexcited electrons in CdSe/CdS core/shell nanorods was studied using optical-pump THz-probe spectroscopy. Measurements were conducted on two samples, differing in rod length. After photoexcitation the hole localizes in the CdSe core within a picosecond, while the electron delocalizes around the core. Analysis of the THz mobility with a model of one-dimensional electron diffusion on a finite rod yields an electron delocalization of similar to 25% into the CdS shell and a mobility of 700 cm(2)/(V s). This is one and a half times the mobility value for bulk CdS, which can be due to quantum confinement effects on electron-phonon scattering and electronic structure.