Deposition of high-density Au nanoparticles on ITO glass by centrifugation

A high and controllable area density Au nanoparticles (NPs) deposition method through centrifugation on indium tin oxide (ITO) is proposed. Area densities as high as 509 NP/µm2 for 10-nm Au NPs and 130 NP/µm2 for 20-nm Au NPs are obtained with relative centrifugal force of 2397 g and larger than 16 min centrifugation time. Using centrifugation method, the Au NP area density can be increased 50 times and 13 times for 10 and 20-nm Au NPs when compared with droplet-only method. A theoretical model is developed to describe the Au NP movement under centrifugation and predict the area density of Au NP on ITO glass. Approximations are applied to derive the analytical expressions for linear and saturation regions. After the beginning of centrifugation, the area density increases linearly with centrifugation time in the initial stage, while the area density gradually saturates when the electrostatic force exerting by the Au NPs on the ITO glass cannot be neglected. Transition phase between the linear and saturated regions is obtained through curve fitting. The model matches well with experimental results in corresponding regions which demonstrate the high-density and cost-effective deposition method for Au NPs on ITO.