Separation of ultrafast photoexcited electron and hole dynamics in CdSe quantum dots adsorbed onto nanostructured TiO2 films

摘要

The ultrafast photoexcited electron and hole dynamics of CdSe quantum dots u0002QDsu0003 deposited ontonnanostructured TiO2 films were studied using an improved transient grating u0002TGu0003 technique. Byncomparing the TG responses measured in air and in a Na2S solution u0002hole acceptoru0003, we succeedednin separating the dynamic characteristics of photoexcited electrons and holes in the CdSe QDs. Wenfound that charge separation in the CdSe QDs occurred over a very fast time scale from a fewnhundreds of femtoseconds in the Na2S solution via hole transfer to S2− ions to a few picoseconds innair via hole trapping. © 2010 American Institute of Physics. u0004doi:10.1063/1.3533374