ARIT 2017 Poster Session Feature: Peter Schindler
Going beyond pure text, bridges will feature Austrian scientists from a new perspective in 2018, taking creative cues to communicate their science in a different light, tone, and color.
Discover the work of Peter Schindler, our fourth scientist featured in the ARIT 2017 Poster Session Showcase.
What do I want to achieve with my research?
Rather than with text, our scientists, answer this essential question using an image, emoji, cartoon or limerick.
"How does my research make others feel?"
Our scientists mimics speak stronger than words!
Your Science in Action: Converting heat to electricity, with as little work as possible!
Energy efficiency and reduction of greenhouse-gas emissions have been a prime focus of environmental groups and Green activists in recent decades, but the media often overlook the scientists whose research leads to the new approaches and energy-saving technologies. One of these scientists is Peter Schindler, a recipient of the Schrödinger Fellowship and now a postdoc at Stanford University. His previous educational and research background in thin film solar cell and renewable energy research, combined with a knowledge of nanotechnology techniques used in semiconductor applications, were an ideal preparation for designing and improving thermionic energy converters (TECs).
TECs use heat from very hot sources (heat that would otherwise be wasted) to generate electricity: Electrons emitted from a high-temperature cathode (negatively charged electrode) are collected at the cooler anode (positively charged electrode). Even non-physicists will appreciate that a material that easily releases electrons from its surface would be a very valuable component of such a system. The measure of how much energy is required for electrons to escape the material surface is called the “work function.” For most materials, the work function is relatively high (as illustrated in the cartoon above). Schindler’s current research involves finding and fine-tuning new materials that have highly-desirable low work functions, and using them to convert waste heat into electricity. Increasing the net energy yield enhances the efficiency of a process and reduces CO2 emissions relative to the amount of useful energy produced.
“TECs aren’t directly competing with other renewable energy sources,” notes Schindler, “as TECs are used for high temperature applications that typically occur in combustion processes.” He feels that solar energy conversion is “unbeatable” as well as very economically competitive. However, TECs are extremely well-suited for use in industrial processes that produce lots of waste heat that would otherwise be lost. And not all TEC applications are at the macro level: Even the water heater in your home loses a significant fraction of energy as heat – energy that a TEC could convert back to electricity.
So … what types of materials easily release their electrons? One novel approach is to combine 2-dimensional materials with coatings of electropositive atoms (i.e., alkaline metals). A 2-dimensional material is “an atomically thin layer ordered only in two dimensions,” Schindler explains. One example is graphene, a familiar substance much like the (3-dimensional) graphite in your pencil. In graphite, carbon atoms are tightly bound within each sheet, but so loosely bound to overlying or underlying sheets that carbon atoms can rub off onto the paper when you write. The 2-dimensional graphene is only one carbon atom thick. “A 2-dimensional material … doesn’t really have a surface,” says Schindler. “It kind of IS a surface in and of itself.” Placed in an electric field, electrons from graphene’s carbon atoms shift to a higher energy level (unlike 3-dimensional materials, whose surface states pin that energy level) and thus are more easily released from the surface.
The research described on Schindler’s ARIT poster utilized a computational simulation approach (“density functional theory”) based on quantum mechanics to predict the electronic properties of graphene monolayers with different coatings of cesium (Cs) (electropositive atoms). The cesium coating creates local dipoles that facilitate the release of electrons from the graphene monolayer. About 30–40% of a monolayer (~1 Cs atom per 60 Å2 of the 2-dimensional carbon lattice) proved to optimize the ease of release – the more easily electrons can escape, the better! The proper combination of a 2-dimensional material and the optimal electropositive atom coating can drastically increase TECs’ energy conversion efficiency.
While the theoretical maximum efficiency of a TEC is much higher than for conventional thermoelectric converters, the conversion efficiencies actually achieved have only been around 10%. However, two recent advances have opened an avenue towards high-efficiency TECs: ultra-low work function materials (described above) and wafer-scale fabrication processes. The latter enables low-cost, high-precision manufacturing via micro machining and wafer bonding processes. In the photo above, Schindler holds a wafer typically used in the semiconductor industry; the high reflectivity is due to its atomically smooth surface.
Schindler foresees that: “Research on novel materials and new fabrication approaches could establish low-cost, scalable, and high-efficiency TECs that could be used for virtually every industrial high-temperature process, as well as residential water heaters.” The future of his field looks nearly as bright as a cesium-coated wafer!
My favorite scientist:
I don’t really have one favorite scientist but I will pick one who is probably not known to everyone: Emmy Noether. She was a German mathematician (1882–1935) who formulated one of my favorite theorems in theoretical physics. Noether’s theorem elegantly connects symmetry in a system with a corresponding conservation law (e.g., symmetry with respect to spatial translation implies conservation of momentum). In addition, I’d like to mention two well-known Austrian physicists: Erwin Schrödinger and Ludwig Boltzmann. They worked at my alma mater (University of Vienna) and have made a huge impact on modern day physics – including my current research field!
If you read one science website/ blog/ book, it should be:
Minute Physics. They do a great job of illustrating and explaining complicated concepts and ideas from physics.
Without science, I would be:
Hard to imagine, but maybe a graphic designer. This skill has come in very handy for creating neat-looking figures and illustrations for scientific publications, although the cartoon above actually pushed my skill beyond what I’m usually capable of …
My Eureka moment was when:
It is almost impossible to pin down one specific Eureka moment because, during my undergraduate studies, I went through many epiphanies – moments when difficult (and even counterintuitive) theoretical concepts finally clicked! To name a few: quantum mechanics, Noether’s Theorem (as mentioned above), and the special and general theory of relativity.
ABOUT THE SERIES
The ARIT 2017 Poster Session Showcase will highlight select Austrian scientists of the Research and Innovation Network Austria. These scientists all participated in the coveted ARIT 2017 Poster Session, after having been selected by an expert jury from the ASCINA network and the Austrian Marshall Plan Foundation.