processing method for copper indium gallium selenide (CIGS) – based solar cells. While conventional methods utilize crystalline silicon,
which entails relatively high costs, it has been proven that CIGS panels have a higher efficiency potential and are cheaper to fabricate than their silicon counterparts.
Professor Yang Yang led his team at the Department of Material Science and Engineering to design a low-cost technique to fabricate copper-indium-diselenide solar cells that could be produced on a large scale. Until now, manufacturing of CIGS panels has been a challenge.
“This CIGS-based material can demonstrate very high efficiency,” said William Hou, a graduate student on Yang’s team and the first author of the study. “People have already demonstrated efficiency levels of up to 20 percent, but the current processing method is costly. Ultimately the cost of fabricating the product makes it difficult to be competitive with current grid prices. However, with the solution process that we recently developed, we can inherently reach the same efficiency levels and bring the cost of manufacturing down quite significantly.”
Conventional CIGS solar cells are manufactured through a vacuum evaporation technique called co-evaporation. This process is not only time consuming, but comes at high costs. The process starts with the active elements of copper, indium, gallium and selenide heated and layered on a surface in a vacuum environment. The challenge in producing CIGS cells lies within this uniform composition of materials on a large scale using a vacuum.
Yang’s team completely eliminates the troublesome vacuum evaporation step. Their primary material, which consists of copper, indium and diselenide, can be easily applied into solar cells in three steps – dissolved into a liquid, applied and baked. The liquid consists of a hydrazine solvent, which is used to dissolve copper sulphide and indium selenide to create the constituents for the copper-indium-diselenide material. The absorbent layer of a solar cell would only be the CIGS material, which the researchers have created in solution form and which can be directly painted onto a surface of any size and baked.
“In our method, material utilization is one advantage. Another advantage is our solution technology has the potential to be fabricated in a continuous roll-to-roll process. Both are important breakthroughs in terms of cost,” said Hou.
The team’s goal is to reach an efficiency level of 15 to 20 percent. Current efficiency levels stand at 9 percent. Yang predicts that the product is three to four years away from 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.” said Yang. It is hoped that this technology will lead to not only a new green awareness in the U.S., but also that it may develop more social and economic activities.
TFOT has previously written about a method to obtain cheap solar electricity that enables production of several hundred feet of “solar sheet” per minute and relies on recent advances in the field of nano-structured materials. We have also covered low-cost, bio-based solar cells that are produced using bio-based materials from renewable plant sources. You are also welcome to check out our article on aigo’s portable solar charger for mobile devices, which allows users to extend their time between conventional charges and operate devices for longer periods of time off the grid.
Additional information on CIGS panels can be obtained at the UCLA website.
Icon image credit: National Renewable Energy Laboratory