Laser Processes and Module Technology
Thin film solar modules are composed of several series-connected solar cells. The series connection is realized by means of selective laser ablation. The group Laser Processes and Module Technology investigates and optimizes the required laser processes, i.e. the selective ablation of the front contact, absorber and back contact.
The series connection of the individual solar cells leads to a reduction of Ohmic losses in the thin film module and to a higher output voltage. The quality of the laser ablation processes strongly affects the performance of thin film modules. Therefore it is important to investigate and understand the ablation processes in detail. For the investigation an automated laser patterning system is used that is equipped with several Q-switched solid state lasers with different wavelengths, pulse durations and beam geometries.
In addition to the optimization of the ablation processes new series connection concepts are in development which offer the potential to achieve higher conversion efficiencies. Furthermore, we work on the simplification of the patterning process with fast and cheap processes like screen-printing and ink-jet printing.
Apart from developing laser processes for the series connection of solar modules we also work on several other topics. For example the fabrication of complex contact geometries that are sometimes required for specific material characterization techniques. Furthermore, we develop laser processes to modify and optimize material properties of all layers used in typical thin-film silicon solar cells.