Optimized laser patterning for high performance Cu(In,Ga)Se₂thin-film solar modules

The thin-film solar cell market has seen a period of consolidation during the last years and many involved companies were forced to stop production due to increasing price pressure from competing cell technologies. Today, thin-film solar industry is gaining momentum again. Especially Cu(In,Ga)Se2 technology evolves at high pace fired by recently achieved record efficiencies of 20.4 percent on flexible polyimide substrate [1] and 20.8 percent on glass substrate [2]. Fresh companies are preparing market entry with matured products and manufacturing technology suitable for high-volume and high-throughput production. Among these key-enabling technologies is laser patterning for cell-to-cell interconnects. Several research groups worked on efficient and reliable laser processes that are now ready for the industrial assessment. Here we present a set of work-horse processes for P1, P2 and P3 scribing of CIGS cells on glass substrate. Optimized parameters are presented for 532 nm and 1064 nm using 50 ps pulses from an all-in-fiber laser system. We further demonstrate the successful realization of functional 8-cell modules with a reduced “dead-zone” width of 70±5 μm and high efficiencies. The certified efficiency of 16.6 percent for our low-dead-zone champion module confirms the observation that shrinking of interconnects has no adverse effects on their electrical quality.