M.R. Watt, Ro.A. Gerhardt
Georgia Institute of Technology,
Keywords: glass nanocomposites, conductivity, solar cell applications, screen printing
Summary:The objective of this research is to fabricate, beginning with screen printing, electrically conductive glass nanocomposite films and optimize their properties. By discovering an optimum thickness and nanoparticle spacing within the glass matrix, we may create a film that can be tailored for many applications such as solar panels and touchscreens. Currently we lack inexpensive, conductive films and coatings that are also durable. Development of such a material would have a substantial impact on electrical devices. Solar cells would be less expensive and easier to fabricate which makes the initial cost to use green energy lower. Photovoltaic solar cells and touch screens commonly use indium tin oxide (ITO) films which is a transparent conductive material. The issues with ITO is that indium is an expensive rare element which is commonly deposited by vacuum sputtering that can lose up to 70% of the material to the walls of the chamber. Fabrication of a glass matrix nanocomposite film containing ITO or any other conductive filler would limit the amount of filler used, while screen printing would eliminate the major losses. While there has been previous research into the creation of electrically conductive bulk glass matrix composites and polymer composites containing antimony doped tin oxide (ATO) and ITO, little research has been conducted into the film versions of the glass nanocomposites. The glass nanocomposites are important because they can withstand a range of environments, particularly higher temperatures. In this project we will evaluate the thickness of the films and the details of the networked glass nanocomposites. In order to achieve reasonable levels of conductivity, the conductive particles need to create a network that travels throughout the film. The initial design will be hexagonal which was chosen because highly conducting materials always contain this high density arrangement. The size and thickness of the hexagons and their effect on the properties will be characterized. The conductive particles (ITO) will be deposited onto a substrate in the described pattern via screen printing then the glass will be screen printed on top. Screen printing allows for fast, reproducible construction of samples that may also be scaled up to industrial proportions. The final step in the fabrication of the glass nanocomposite films will be to compression mold the films for complete glass infiltration into the spaces of the conductive particle network. The difficulty of this step is that a compression molding machine reaching the temperatures required, approximately 700oC, does not currently exist at this time. Therefore, we are currently designing a custom made apparatus. The network films will be analyzed repeatedly throughout fabrication using atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and impedance testing. COMSOL Multiphysics simulations will also be used to simulate the thin film’s properties including electrical conductivity.