Enhancement of adjustable localized surface plasmon resonance in ZnO nanocrystals via a dual doping approach.

Recently, the localized surface plasmon resonance (LSPR) concept was expanded from noble metals to doped semiconductor nanocrystals (NCs). However, the strengthening of the intrinsically very weak LSPR in NCs remains a great challenge for its applications in optics, electronics and optoelectronics fields. In this work, we report on the remarkable strengthening and controllability of LSPR in ZnO through a dual-doping strategy. First, high quality In-doped ZnO (IZO) NCs with intense LSPR were synthesized by a simple single-pot method. Importantly, the LSPR can be tuned by simply adjusting the concentration of In dopant, as well as by UV light irradiation (photo-induced doping). The pattern of electricity of an IZO NC film matches the shift of LSPR independent of dopant concentration. The UV light irradiation clearly enhanced the electrical properties of the films (350Ω/sq) due to increase carrier density explained by LSPR and confirmed by X-ray photoelectron spectroscopy. The IZO NCs can be easily dispersed in various organic solvents and serve as inks for assembling uniform films via solution processes. These IZO NC ink is promising for application in next-generation solution-based field effect transistors and other optoelectronic devices.