Technology
We develop and sell production equipment for the manufacturing of thin film modules using a Copper-Indium-Gallium-Diselenide (CIGS) absorber film.
CIGS technology offers many benefits:
- Material-saving production without silicon
- Highest potential regarding module efficiency among thin film technologies
- Free choice of cover glass based on application
- No degradation
In addition to the CIGS absorber layer, the modules consist of a metallic contact on the rear side as well as a transparent and electrically conductive front contact. The different layers are deposited successively onto the glass substrate that is used both as carrier material and as component for the subsequent encapsulation of the module.
centrotherm photovoltaics has developed its own production technology which it has secured through various patent registrations. The benefits in brief:
- Our process steps are easily scalable to large areas
- Very short cycle times ensure extremely high productivity
- No use of toxic or explosive process gases
- Relatively small production area
Our production technology
After a wet mechanical cleaning process with subsequent air-knife drying the glass substrate is deposited by means of a sputtering process with a molybdenum layer that is to be utilized as rear side contact. In the many years since its introduction to the industrial market, the sputter technology of our subsidiary FHR Anlagenbau has become a successfully proven method for applying a homogeneous coating to large surfaces of architectural glass products.
In the next step, the CIGS absorber film is produced in our patented sequential process. Similar to the molybdenum deposition in the previous process, the metallic precursors (copper, indium and gallium) are deposited on the substrate using sputter equipment. The finishing deposition of elemental selenium is deposited in an ultra fast, cost effective and simple atmospheric process. In the second step, the CIGS crystal phase is thermally activated in our conveyor furnace. Thanks to the treatment of the absorber layer in an atmospheric phase transformation process and the high-speed process flow, our customers take the benefit from the currently most efficient and cost-effective technology available on the market for the production of CIGS absorbers.
After the completion of the absorber film, a buffer layer of n-type conductive cadmium sulfide is applied to the substrate by means of chemical reaction in a wet process system. Alternatively our R&D department is currently testing cadmium-free buffer layers.
In the final step, an n-type front contact of aluminum zinc oxide is deposited as transparent conductive oxide layer in a dual-phase sputter process. In CIGS thin-film technology, the production of solar cells and modules is combined in a single process flow. In order to split the module into single cells and interconnect these to form a (monolithic) series circuit, the module must be patterned several times within the different layers by laser or scribing processes (P1, P2, P3).
After the contacts were installed at the two outermost cells, the module is encapsulated and sealed using EVA foil. Subsequently a glass panel cover is mounted onto the raw module and, finally, the junction box is installed on the rear side and the modules are sorted based on a final IV measurement.
