Laser Patterning of thin Film Solar Cells for Building-Integrated PV

This study reports on the patterning of thin-film solar cells on soda-lime glass using a molybdenum back contact. A 1064 nm nanosecond laser was used to remove single and multilayers by irradiating the Mo layer through the glass. The ablation threshold for the Mo layer provided a guideline to remove multilayers and device stacks. Patterning in atmosphere was problematic due to ablated vapor redeposition on the sample surface and pattern edge defects causing shorting of the devices. Moving the process to a water medium, where ablated vapor was carried away by flowing water in contact with the device layers, improved the aesthetic appearance and functionality of the patterned devices. Mechanical scribing was used to enhance the edge isolation and realize device performance close to that of the pattern-free test cells.