Tosoh SMD, a maker of the type of sputtering targets often used by photovoltaic manufacturers, says it has developed a new transparent conducting oxide target that can add a 1 percent gain to the solar conversion efficiencies of thin films.
According to a company news release, the new TCO targets (available in either indium tin oxide or aluminum zinc oxide flavors, with planar and rotary options) have been specially doped to have improved transparency and other optical properties. It says they “are highly transparent, especially in the visible to infrared range, and that feature high thermal stability, including under humid conditions … [and] enable the deposition of textured surfaces that feature enhanced light-trapping capability. Compared with thin films from conventional TCO targets, a single-junction thin film deposited by a Tosoh AZO TCO target in a silicon solar cell shows a one-point gain in conversion efficiency. Thin films, meanwhile, produced with Tosoh’s ITO TCO target achieve a similar gain in a copper indium gallium selenide-based solar cell.”
One CIGS expert seems to be happy with this. According to the release Makoto Konagai, of the Tokyo Institute of Technology, says that “this invention will contribute to achieving the goal of 18% energy conversion efficiency with a focus on low-cost and large-scale production.”
Just to clarify, I think Konagai’s reference to 18% conversion efficiency is to volume-produced CIGS, not lab tests. The NREL reached a CIGS thin-film efficiency mark of 19.9 % back in 2008, and has confirmed that at least one manufacturer has commercial units available that reach the 15.5 % conversion level.
Despite some nifty technical developments, interest in thin-film makers, especially in the United States, has waned as processing and manufacturing prices for traditional silicon PV units has continued to fall.
Tosoh is hoping to attract worldwide customers who are interested in lowering their overall cost per watt of production. I suspect some of the company’s timing of this announcement may be linked to Europe’s “Thin Film Solar Summit” that starts March 3 in Berlin.