Shell-thickness-dependent photoinduced electron transfer from CuInS 2/ZnS quantum dots to TiO2 films

Abstract

We demonstrate the electron transfer (ET) processes from CuInS 2/ZnS core/shell quantum dots (QDs) into porous anatase TiO 2 films by time-resolved photoluminescence spectroscopy. The rate and efficiency of ET can be controlled by changing the core diameter and the shell thickness. It is found that the ET rates decrease exponentially at the decay constants of 1.1 and 1.4 nm-1 with increasing ZnS shell thickness for core diameters of 2.5 and 4.0 nm, respectively, in agreement with the electron tunneling model. This shows that optimized ET efficiency and QD stability can be realized by controlling the shell thickness. © 2013 American Institute of Physics.