Fraunhofer ISE has teamed with industrial partners Merck, Heraeus and ASYS to produce fine line contacts with widths under 35µm, employing new materials and contactless techniques to reduce shading and boost conventional solar cell efficiencies.
Employing a newly developed automatic dispenser with ten-nozzle printhead, new materials developed by Merck and Heraeus are placed on the surface of solar cells in a contactless printing process which utilises ultra-fine openings in a strictly parallel printing head.
The extrusion process pushes the metallisation paste through 50µm sized openings of the printhead dispenser in a parallel motion.
According to Fraunhofer ISE, the result is a reduced contact width by around a third, compared to standard screen printing processes, while maintaining the same cross-sectional contact area. Also ‘mesh marks’ are eliminated.
“The Photovoltaic Technology Evaluation Center PV-TEC at Fraunhofer ISE provides us with a truly excellent infrastructure for these types of new development,” said project manager Dr. Florian Clement. “We are able to carry out every single step here, from detailed characterisation of media flow behavior to the manufacture of highly efficient silicon solar cells. We also simulated the fluid dynamics of the extrusion process here to develop the printhead architecture.”
Fraunhofer ISE noted that the dispensing technology has the potential to replace conventional screen printing tools in cell manufacturing and that manufacturers are already showing “great interest” in the dispensing technology and were already providing test wafers to Fraunhofer ISE for processing.