According to researchers at Oregon State University (OSU), everyday inkjet printers used in homes and offices around the world could hold the key to the future of cheap thin film solar cell production.
More specifically, it is the inkjet’s dye delivery system that dramatically cuts the amount of time and waste of expensive and rare elements used in current methods of fabricating thin-film “CIGS” (Copper Indium Gallium Selenide) solar cells that has the OSU team, led by Chih-hung Chang, Professor in the School of Chemical, Biological and Environmental Engineering, excited.
"Some of the materials we want to work with for the most advanced solar cells, such as indium, are relatively expensive," Chang says. "If that’s what you’re using you can’t really afford to waste it, and the inkjet approach almost eliminates the waste."
Inkjet technology has been used before in solar panel manufacture to spray light-sensitive silicon nano-particles onto crystalline cells, but CIGS technology is potentially much more efficient at converting sunlight to electricity and the flexible thin-film plastic substrate used in the process is easier to manufacture.
The focus of the OSU study, published in the Solar Energy Materials and Solar Cells journal, is on the inkjet delivery of the compound chalcopyrite. A layer of chalcopyrite one or two microns thick has an energy conversion rate almost 50 times that of silicon. Current approaches use vapour absorption to deliver the material onto the cell, an expensive and toxic process.
Chang’s team has successfully developed a dye that prints chalcopyrite onto thin film using inkjet technology with a solar conversion rate of 5 percent. With more research, they say a commercially-viable 12 percent conversion rate is achievable.
The researchers are working on using the inkjet process has the potential to enable solar cells to be incorporated directly into building materials.
"In summary, a simple, fast, and direct-write, solution-based deposition process is developed for the fabrication of high quality CIGS solar cells," the researchers wrote in their conclusion.