(505b) In-Situ Characterization of Electrophoretic Deposition Using the Quartz Crystal Microbalance

Electrophoretic deposition (EPD) is a process in which colloids in a liquid suspension are deposited onto an electrode using an electric field. EPD allows for fast deposition over complex shapes, is easily scalable to large areas, and can be used with a diverse material set. Recent work has demonstrated that EPD can be used as a three-dimensional printing technique [1], renewing an interest in developing more quantitative deposition models for nanocrystal colloids. Since there are few studies that use in situ methods to quantify particle deposition, the mechanisms of electrophoretic deposition are explored traditionally through analytic models that seek to capture EPD kinetics. In our work, we use a Quartz Crystal Microbalance (QCM) to determine particle deposition in real-time. The QCM is a piezoelectric device that dynamically measures the change in resonant frequency due to particles depositing onto the face of the QCM, which acts as the electrode. We then use the frequency shift to extract deposited mass as a function of time, which enables exploration of several aspects of deposition. With the QCM, we measure the minimum voltage needed for particles to begin depositing, the deposition rate, and the dissolution rate (for unstable colloid films). A comparison with measured current response allows us to correlate mass transfer with the charge transfer of the particles. By varying deposition parameters such as particle concentration, deposition time, and applied electric field, we develop datasets that compares different colloids and solvents. Here, we present our experimental techniques and results from parameter studies compared with analytic models of our system.

This work was supported by the Lawrence Livermore National Laboratory Directed Research and Development Program, 16-ERD-033 and performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

[1] Pascall, et al. Advanced Materials. 2014.