UCLA researchers have developed a low-cost solution processing method for CIGS-based solar cells. Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have developed a low-cost solution processing method that could provide an answer to the manufacturing issues facing CIGS-based solar cells.

In a new study to be published in the journal Thin Solid Films on July 7, 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 processing method for their copper-indium-diselenide solar cells which have the potential to be produced on a large scale.

The copper-indium-diselenide thin-film solar cell developed by Yang's team achieved 7.5 percent efficiency in the published study but has, in a short amount of time, already improved to 9.13 percent in the laboratory.

Copper-indium-gallium-selenide or CIGS can serve as an alternative to crystalline silicon in the manufacture of solar panels.

CIGS solar cells have a high efficiency potential and may be cheaper to produce than silicon solar panels as they would use less raw materials. However, manufacturing CIG panels on a commercial scale has so far proved difficult.

Currently, most CIGS solar cells are produced using vacuum evaporation techniques called co-evaporation, which can be costly and time-consuming. The active elements — copper, indium, gallium, and selenide — are heated and deposited onto a surface in a vacuum.

The copper-indium-diselenide material created by Yang's team does not need to go through the vacuum evaporation process. Their material is simply dissolved into a liquid, 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 copper-indium-diselenide material.

In solar cells, the "absorber layer" (either copper-indium-diselenide or CIGS) itself is the most critical to performance and the most difficult to control. Their copper-indium-diselenide layer, which is in solution form, can be easily painted or coated evenly onto a surface and baked.

The team's goal is to reach an efficiency level of 15% to 20%. Yang predicts three to four years of further study and research before commercialization.

The study was funded in part by the NSF Integrative Graduate Education and Research Traineeship-Materials Creation Training Program.


- Katrice R. Jalbuena