For most people, experiments involving a home microwave typically don't go much further than inflating a marshmallow like a balloon or reheating leftovers in plasticware – both with messy results. For metallurgists though, microwaves are sometimes employed to efficiently process metals, which is how researchers at the University of Utah found themselves using a secondhand kitchen appliance in their lab. Their resourcefulness paid off recently, when the team discovered a method for creating solar cell material with just a few basic ingredients and an old microwave.
The material is called CZTS after its components, copper, zinc, tin, and sulfur, and is known to act as a photovoltaic semiconductor, converting the sun's rays into usable electricity. Scientists have only recently begun turning to it for use in commercial-grade solar cells, since its low-cost, environmentally friendly ingredients make it a perfect fit with green energy sources. Unfortunately, CZTS has been difficult to create properly in the past and usually requires more complicated methods involving chemical suspensions.
The resulting CZTS is suspended in an ink-like substance, which can be painted onto most surfaces or combined with other substances to build a functional solar cell. Sarswat and Free even built a small photovoltaic cell to prove their microwave-made CZTS would work. Leaving the CZTS in the microwave for specific times will also form different sizes of nanocrystals, giving the material different properties. Larger crystals absorb heat and convert it to electricity, while smaller crystals can be made to emit light at certain energy levels. The two researchers believe this could lead to LEDs that require less power.
Sarswat and Free also learned during the course of their study that a research team at Oregon State University was developing a similar microwaving method, though their process uses different chemicals. The pair of metallurgists are now performing further experiments to improve their process and find more applications for CZTS. Besides solar cells, they've also looked at possibly incorporating the material into biological sensors, hydrogen fuel cells, and electronic circuitry, though it's still too soon to tell when or if any of these ideas will lead to a commercial product.
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