Chih-hung Chang, an associate professor of Chemical Engineering, is developing new approaches to solar energy that may dramatically lower their cost while reducing waste and environmental impacts. (Oregon State University).
Oregon State University researchers have made an important breakthrough in the use of continuous flow microreactors to produce thin film absorbers for solar cells - an innovative technology that could significantly reduce the cost of solar energy devices and reduce material waste.

This is one of the first demonstrations that this type of technology, which is safer, faster, and more economical than previous chemical solution approaches, and could be used to continuously and rapidly deposit thin film absorbers for solar cells from such compounds as copper indium diselenide.

Previous approaches to use this compound – which is one of the leading photovoltaic alternatives to silicon-based solar energy devices – have depended on methods such as sputtering, evaporation, and electrodeposition. Those processes can be time consuming, or require expensive vacuum systems or exotic chemicals that raise production costs.

Chemical bath deposition is a low-cost deposition technique that was developed over a century ago. It is normally performed as a batch process, but changes in the growth solution over time make it difficult to control thickness. The depletion of reactants also limits the achievable thickness.

The technology invented at OSU to deposit “nanostructure films” on various surfaces in a continuous flow microreactor, however, addresses some of these issues and makes the use of this process more commercially practical.

“We’ve now demonstrated that this system can produce thin-film solar absorbers on a glass substrate in a short time, and that’s quite significant,” said Chih-hung Chang, an associate professor in the School of Chemical, Biological, and Environmental Engineering. “That’s the first time this has been done with this new technique.”

Further work is still needed on process control, testing of the finished solar cell, improving its efficiency to rival that of vacuum-based technology, and scaling up the process to a commercial application, Chang said.

Thin-film solar cells produced by applications such as this could ultimately be used in the creation of solar energy roofing systems. Conceptually, instead of adding solar panels on top of the roof of a residential or industrial building, the solar panel itself would become the roof, eliminating such traditional approaches as plywood and shingles.

(Oregon State University)