Antifreeze material could cut cost of solar cells

Engineers at Oregon State University have determined that ethylene glycol, commonly used in antifreeze products, can be a low cost solvent that functions well in a continuous flow reactor – an approach to making thin film solar cells that is easily scaled up for mass production at industrial levels. According to the researchers, the approach will work with CZTS, or copper zinc tin sulfide, a compound of significant interest for solar cells due to its excellent optical properties, low cost and environmentally friendly design. "The global use of solar energy may be held back if the materials we use to produce solar cells are too expensive or require the use of toxic chemicals in production," said Greg Herman, an associate professor of Chemical, Biological and Environmental Engineering at OSU. "We need technologies that use abundant, inexpensive materials, preferably ones that can be mined in the US This process offers that." The technology being developed at OSU uses ethylene glycol in meso-fluidic reactors that Herman says can offer precise control of temperature, reaction time and mass transport to yield better crystalline quality and high uniformity of the nanoparticles that comprise the solar cell – all factors which improve quality control and performance. The approach is also said to be faster – many companies still use batch mode synthesis to produce CIGS nanoparticles, a process that can ultimately take up to a full day, compared to about half an hour with a continuous flow reactor. "For large scale industrial production, all of these factors – cost of materials, speed, quality control – can translate into money," Herman concluded. "The approach we're using should provide high-quality solar cells at a lower cost."