Department of Chemistry (Optoelectronic Materials)
Joined SFU in September 2014
Dr. Kaake is interested in understanding the transport of ions, charges, and heat in polymeric and molecular films. These materials are already used in computer and cell-phone displays and will someday be in widespread use as solar cells and transistors. The properties that make organic materials useful in optical and electronic devices rely on the transport of one or more things through the film. His group uses a combination of electrical and spectroscopic measurements to understand transport processes at the nanoscale. A deep understanding of these phenomena will catalyze the development of materials with significantly better properties and lead to new applications.
Why are you so drawn to working on carbon electronic materials?
For a number of years now I’ve been studying electronic materials made from plastics, dyes, and organic molecules. Given the incredible diversity of compounds made of carbon (e.g., as seen in Nature)—you can do just about anything with carbon—my research group is motivated by the idea of making electronics with it. As it turns out, it’s a real challenge to make electronic materials from carbon. We are trying to understand how to make the electrons move faster, how to make the capture of solar radiation more efficient for solar power, and what makes these materials unique, and then harness carbon-based materials for applications that can make a difference in people’s lives.
I see tremendous potential in carbon-based electronics because carbon is the stuff of life and the diversity of the molecules that you can make is practically infinite - you can arrange carbon atoms in an infinite number of ways. If it is theoretically possible within the laws of the universe to make fantastic electronic devices with carbon based materials, I think a great number of them will be made from carbon. Modern electronics is built on silicon, a great material that will always be used in certain things, like your desktop computer. However, you can do all sorts of interesting things with carbon that cannot be done with a block of silicon – with carbon you’ve got self-assembly processes, and the atoms can interact and arrange themselves in interesting patterns to make unique structures and functionalities that are not easily possible with conventional materials.
Why are you interested in fabricating electronic materials by crystallization from supercritical fluids?
There are practical problems I am trying to address with supercritical fluids. Organic materials work better if you can make them in a predictable way. Normally a drop of material is placed on a spinning piece of glass to create a film. These films are usually not well-ordered and not predictably arranged, which can have a negative effect on their properties; and it makes it hard to understand what is going on when every piece of the material looks a little bit different.
We want to use crystallization in supercritical fluids to grow perfect materials. I think at some level people do not understand just how good these materials could be because it is hard to grow them in anything but a disordered way. We are aiming for a perfect material, one with atoms arranged into a highly ordered structure in which the charges can move without running into any ‘funny business’. Imagine a polymer chain as a wire and you are sending an electron down the wire: if the wire is straight, the electron goes a lot faster than if it has to go on a roller coaster ride to get where it is going. The idea of using crystallization from supercritical fluids is to obtain ordered structures, to straighten out those roller coaster tracks and assess how fast the electrons can go. Structurally ordered, perfect materials could then be obtained and compared to determine which is better.
There are other reasons to pursue crystallization from supercritical fluids. For example, this technique can be used to pattern materials in ways that allow you to make smaller devices. The current spin-coat or ink-jet printing methods have a limitation in the line-width that you can form, whereas I think using the supercritical fluids approach will get around that problem.