Time-resolved photoinduced charge dynamics of Cd chalcogenide-based materials

We have performed a comparative analysis of the photocharging dynamics of quantum dots (CdSe-CdS core-shell nanoparticles in toluene) and a bulk CdS single crystal by using time-resolved luminescence and transient grating techniques. The quantum dots were obtained through a colloidal synthesis method in aqueous-organic media with the average sizes of 2 nm and 2.9 nm. It has been shown that the relaxation of the photocharging dynamics in quantum dots is well fitted by the double-exponential decay function with time constants of a few and tens of picoseconds, which indicates that the energy loss of photoinduced charges is mainly the result of electron-phonon interaction.