Date: 5 February 2010
In this project, Ferro will engineer a vitreous glass frit system to provide reliable air-tight and water-tight seals for thin-film solar cells. If successful, the new sealing materials will enable Ferro to solve a significant problem with second- and third-generation thin-film solar cells, such as copper-indium-gallium-(di) selenide (CIGS), Cadmium/Telluride (CdTe), copper-indium- selenide (CIS) and Organic Photovoltaics (OPVs).
Although the efficiency of these solar cells has been improving rapidly, they all share the same problem in that they are extremely sensitive to degradation caused by air and moisture. Therefore, they must be hermetically sealed to stop oxygen or moisture in the air from entering the module. Currently, most thin film solar cells are sealed with organic sealants that typically lose their hermeticity in time, especially if exposed to UV radiation. In addition, the seals are exposed to daily and seasonal temperature fluctuations that can weaken the seal even more. No existing organic sealant has demonstrated that it can survive the required 20 plus years of solar module service life without allowing a damaging amount of oxygen or water vapor into the cell.
Glass frit forms the edge seal on a plasma display screen. This technology will be the starting point in developing a seal material for thin-film solar cells.
Ferro has a long history of supplying vitreous glass frit that is field proven to provide a reliable hermetic seal in vacuum devices such as thick-film solar cells, lamps, plasma displays and microelectromechanical systems (MEMS). These materials have been shown to last well beyond the solar cells’ expected lifetimes. The problem to be addressed is that thin film solar cells are very temperature sensitive and cannot withstand the high firing temperatures required by conventional glass frits. The goal of this research project is to develop a glass frit material that can create the required seal at lower temperatures and that can be activated by laser-based and ultrasonic energy systems.
“One of Ferro Corporation’s core technical competencies is the design and manufacture of custom glasses,” said Steve Florio, Chief Technology Officer for Ferro’s Electronic, Color and Glass Materials Group. “We believe this strength in glass technology will enable Ferro to rapidly drive the development of the frits required for this critical new application.”
For this research project, Ferro has formed a product development team that includes The Ohio State University, Edison Welding Institute, and StrateNexus Technologies LLC. The Edison Welding Institute and Oak Ridge National Laboratory have experience with a number of techniques, including laser-based and ultrasonic energy deposition systems, that can potentially create hermetic seals without exposing the cell to damaging high temperatures. By combining these techniques with Ferro's expertise in engineering vitreous sealing chemistries, StrateNexus Technologies expertise in binder synthesis, and OSU’s photovoltaic device engineering, it is anticipated that an advanced durability sealing system can be developed.