Spatio-temporal dynamics of coupled electrons and holes in nanosize CdSe-CdS semiconductor tetrapods

We report on coupled electron-hole transfer, Coulomb drag, in CdSe/CdS semiconductor nanotetrapods. We demonstrate that photoexcited holes can either be transferred to the CdSe core or become trapped in one of the CdS arms. By combining time-resolved pump-probe and photoluminescence measurements we investigate how the Coulomb potential drags the electron to the hole localization site. As supported by effective-mass calculations taking into account Coulomb effects we conclude that the hole dynamics determines the fate of the electron in a coupled dynamics.