Researchers at Oregon State University have found a way to make the sun a “one-stop shop” that both produces the materials for solar devices and the energy to power.
The discovery could drastically reduce the carbon footprint of manufacturing solar materials, according to Chemical engineering professor Chih-Hung Chang.
“Several aspects of this system should continue to reduce the cost of solar energy, and when widely used, our carbon footprint,” said Chang, the lead author of the paper published in the journal RSC Advances.
The work is based on the use of a “continuous flow” micro-reactor to produce nanoparticle inks that make solar cells by printing. Existing approaches are more time-consuming and costly.
“It could produce solar energy materials anywhere there’s an adequate solar resource, and in this chemical manufacturing process, there would be zero energy impact.”
In this process, simulated sunlight is focused on the solar micro-reactor to rapidly heat it, while allowing precise control of temperature to aid the quality of the finished product. The light in these experiments was produced artificially, but the process could be done with direct sunlight, and at a fraction of the cost of current approaches.
In these experiments, the solar materials were made with copper indium diselenide, but to lower material costs it might also be possible to use a compound such as copper zinc tin sulfide, Chang said. And to make the process something that could work 24 hours a day, sunlight might initially be used to create molten salts that could later be used as an energy source for the manufacturing. This could provide more precise control of the processing temperature needed to create the solar energy materials.
State-of-the-art chalcogenide-based, thin film solar cells have already reached a fairly high solar energy conversion efficiency of about 20 percent in the laboratory, researchers said, while costing less than silicon technology. Further improvements in efficiency should be possible, they said.
Another advantage of these thin-film approaches to solar energy is that the solar absorbing layers are, in fact, very thin – about 1-2 microns, instead of the 50-100 microns of more conventional silicon cells. This could ease the incorporation of solar energy into structures, by coating thin films onto windows, roof shingles or other possibilities.