On Harvey Mudd College Week: Reducing the cost of capturing energy from the sun could be crucial to our future.
Hal Van Ryswyk, John Stauffer professor of chemistry, looks at one way to do so.
Hal Van Ryswyk is a materials chemist doing fundamental research on low-cost photovoltaics with undergraduate coworkers at Harvey Mudd College in Claremont, California. A graduate of Carleton College with a PhD from the University of Wisconsin-Madison, he has served as chair of the Department of Chemistry at Harvey Mudd, as a member of the American Chemical Society Committee on the Petroleum Research Fund, and as a visiting professor at MIT, Stanford, Northwestern, and ETH-Zürich.
Printing Solar Cells
Solar energy is available on a scale that dwarfs all other renewable energy sources: the sun sends the Earth more energy in 20 minutes than humanity uses in a year.
While the price of silicon solar panels has decreased enough to make solar cheaper than fossil fuels, fundamental barriers prevent silicon solar panels from becoming affordable enough to supply the world’s energy needs. It’s a question of scale and cost.
To put the scale in context, to power the US economy requires solar panels with an area equivalent to the entire federal interstate highway system. To put the cost in context, current silicon solar panels cost about $100 per square yard, and that’s simply too much!
Third-generation solar cells can be built with a fraction of the material and energy required to build silicon solar panels, thereby drastically reducing cost. In our lab, we use quantum dots in place of silicon.
These semiconductor nanoparticles are used to create inks which can be sprayed, blade-coated, or printed. When the ink dries, the resulting solar cell is thinner than a layer of commercial housepaint. To make good on the promise of third-generation solar cells, we fine-tune quantum dot surface chemistry to maximize efficiency and to allow for cheap, easy processing.
Our goal is to mass produce solar cells on flexible substrates that are 3 feet wide and hundreds of feet long with a cost per square yard equal to that of housepaint, about $20. Reaching this goal would make third generation solar cells a disruptive technology, and market forces would funnel users world-wide to affordable, ubiquitous solar power.
