Roll-to-roll processing of flexible organic solar cells


Flexible organic solar cells constitute an alternative to common mono and polycrystalline solar cells as well as the novel thin-film technologies. Silicon, CIS/CIGS (Copper-Indium-Gallium-Selenide) and Cadmium Tellurid (CdTe) are used as semiconductor material for the last-mentioned technology, which are largely made up of heavy metals. The production of organic solar cells is much more unproblematic in this context.

Flexible organic solar cells are made up of carbon compounds. Besides a reduced environmental impact, less material needs to be used. Furthermore, a great advantage of flexible conductive and semi-conductive polymers is the possibility to apply fast structuring processes and reasonable, large-scale roll-to-roll processes to them. Thereby, the structure of the solar cells is either generated by a printing process or highly precise laser scribing (P1, P2, P3) – both being already successfully used in photovoltaics.

3D-Micromac AG develops and manufactures complete production lines as well as integrated modules for the production of organic photovoltaics. Besides the processing technologies for the build-up of the layers of the cell using different print and coating technologies, 3D-Micromac AG integrates the appropriate laser technology in its systems to structure the cell selectively in the processing steps P1, P2 and P3. Depending on the application, lasers with different wavelengths (IR, VIS, UV) are used. The applicability of laser structuring could now be proven for an industrial process.

The company Heliatek, which is situated in Dresden, has recently opened its first worldwide manufacturing plant for the production of organic solar foils by means of vacuum deposition. 3D-Micromac supplied the laser modules for the P2 and P3 structuring. The special feature is the laser structuring under vacuum conditions. Laser processing under vacuum conditions is different from atmosphere processing.

The laser ablated material cannot be removed by a conventional exhaust unit in order to avoid getting the optics dirty. 3D-Micromac solved this problem with special debris filter unit to remove the ablated material with highest transparency for the laser beam. Production cycles of a hundred and more hours are possible.