New Variations in the Colloidal Route to ErIII@ZnO Nanocrystals and Films

Abstract

1-propanolic particulate ZnO nanocolloids were co-doped with ErIII ions and various silanes prior to coating. The resulting functionalized sols and sintered films were examined by UV/Vis-, FTIR- and time-resolved NIR-fluorescence spectroscopy. As a result, methyl- and phenyl triethoxysilanes (MTEOS, PTEOS) were found to block the slow ageing of the ZnO sols while the higher substituted silanes did not. Furthermore, film samples prepared from TEOS co-doped ErIII/ZnO sols and sintered at 400°C showed no fluorescence whereas PTEOS co-doping allows to detect the complex NIR-ErIII-fluorescence decay. In the last part of this contribution, the effect of thermal ZnO particle healing on the subsequent co-dopings and NIR-fluorescence dynamics will be discussed. Briefly, with increasing healing temperature the life time of the 1.54 μm fluorescence decreases. Interestingly, in ZnO sols healed at 170°C, the erbium acetate precursor is no more soluble which means that the ZnO nanocrystals could not be doped either.