Controlling electron transfer from photoexcited quantum dots to Al doped ZnO nanoparticles with varied dopant concentration

The effects of Al doping on the optical properties of ZnO nanoparticles (NPs) were investigated by steadystate and time-resolved photoluminescence (PL) spectroscopy. The doped NPs were prepared by low temperature hydrolysis process. The optical band gap energy of Al-doped ZnO NPs increased from 3.47 to 3.57 eV as Al doping content increased from 0 to 12%. The deep defect states, such as oxygen acceptor and zinc donor induced by Al doping could significantly influence PL spectra and lifetimes of ZnO NPs. In particular, it was found that the Al doping could obviously suppress the electron transfer process from Cu:Zn-In-S quantum dots to the adjacent ZnO NPs. Moreover, the electron transfer rate kET decreased with increasing Al doping content and decreasing temperature. (C) 2017 Elsevier B.V. All rights reserved.