GSE's Technology Roadmap
• Core equipment: roll-to-roll flexible thin-film co-evaporation deposition, Integrated Cell Interconnect (ICI) packaging
Since 1996, GSE has applied for a range of core patents, which involve optimizing the CIGS thin-film structure and ingredients, using the flexible roll-to-roll technology to manufacture the core equipment of CIGS solar cells and develop its production technique, as well as the whole process of CIGS thin-film solar cells and modules. In total, there are 159 licensed patents and another 242 patent applications that have been filed for approval.
• The production technique of flexible continuous roll-to-roll coating
A production line that uses roll-to-roll magnetron sputter coating and a co-evaporation technique to grow layers of CIGS solar cells on a stainless steel substrate. The main technical features are:
The coating of different layers of a CIGS cell is done in respective dedicated devices;
Features of a film layer shall decide whether sputtering or co-evaporation is used for the coating;
The forepart all adopts the roll-to-roll production;
The front electrode uses ITO film. After the deposition of all layers is done, the finished cells are rolled for packaging. They can be put in a long-term storage or transported to another place to be further packaged, without affecting the modules' efficiency. The cells may either produce BAPV modules themselves or allow third parties to do further development. In the meantime, the cells can be sold and the modules can be manufactured via OEM.
• The Integrated Cell Interconnect (ICI) packaging technique
The ICI packaging technique adopts image-based coating to produce electrodes featuring a tighter inner structure, having lowered the electric resistance of modules connected in series. Cells are connected via laser welding, which solves the issue of short circuits. Thus, the rate of lost efficiency for cells and modules has been largely reduced. And the conversion rate of ICI packaged modules has reached 16%.
• The one-meter-wide stainless steel substrate
A stainless steel substrate of three kilometers long and one-meter-wide is used. It is as thin as 30 μm. On a substrate of such width, the yield rate is improved, thanks to better exclusion of the marginal area's effect while retaining a higher portion of effective material area. In the meantime, ICI modules will be enlarged to conform to the shape factor of PowerFLEX. Accordingly, PowerFLEX's conversion rate is equal to that of the ICI sub-components.
This technique deposits the CIGS layer for photovoltaic conversion on a flexible substrate, with the following advantages:
• Multipoint distributed evaporation sources are adopted to improve the evenness of films deposited;
• Short evaporation process (less than 4 min.);
• Raw materials are easy to acquire (Cu, In, Se particles, liquid Ga);
• Double XRF are used to monitor the thickness and components of films deposited through co-evaporation and compensated by adjusting evaporation sources when off target;
• Raw materials have a high use ratio, materials in the co-evaporation hall can be recollected for reuse;
• Easy dust management (changing the protection panel), and convenient evaporation source maintenance (6 hours maintenance).