UCLA Researchers Develop Low-Cost Processing Method For CIGS-Based Solar Cells

July 09, 2009 by Jeff Shepard

Researchers at UCLA (University of California Los Angeles) claim that they have developed a low-cost solution processing method for CIGS(Copper-Indium-Gallium-Selenide)-based solar cells. In a new study published in the journal Thin Solid Films, Yang Yang, a professor in the school’s Department of Materials Science and Engineering, and his research team show how they have developed a low-cost solution for their copper-indium-diselenide (CIS) solar cells that has the potential to be used for large-scale production.

The published study notes a conversion efficiency of 7.5% for the CIS thin-film solar cell developed by the researchers, but they have since improved the efficiency to 9.13% in the lab. "We started this process 16 months ago from ground zero," said Yang, also a member of the California NanoSystems Institute, where some of the work is being done. "We spent three to four months getting the material to reach 1%, and today it’s around 9%."

The CIS material created by Yang’s team does not need to go through the vacuum evaporation process. The simple process involves dissolving the material into a liquid, then it is applied and baked. To prepare the solution, Yang’s team used hydrazine as the solvent to dissolve copper sulfide and indium selenide in order to form the constituents for the material. In solar cells, the "absorber layer" (either copper-indium-diselenide or CIGS) itself is said to be the most critical to performance and the most difficult to control. According to the researchers, this layer, which is in solution form, can be easily painted or coated evenly onto a surface and baked.

The team states that its goal is to reach an efficiency level of 15-20%. Yang estimates that it will take three to four years before the material is ready for commercialization. "As we continue to work on enhancing the performance and efficiency of the solar cells, we also look forward to opportunities to collaborate with industry in order to develop this technology further" he said.