Flexible Cu(In,Ga)Se2 solar cells fabricated using a polyimide-coated soda-lime glass substrate

Flexible solar cells with a Cu(In,Ga)Se2 (CIGS) absorber layer were fabricated on a polyimide thin film using a lift-off process. Polyimide-coated soda-lime glass (SLG) was used as a substrate for fabricating CIGS solar cells before the lift-off process conducted to make the cells flexible. A conversion efficiency of 13.4% was achieved by low temperature deposition; this value is comparable to that obtained by direct deposition on a rigid glass substrate even without an external Na source. The final conversion efficiency after the lift-off process was 12.7% with some area correction due to the partial peeling-off between CIGS and Mo. Open-circuit voltage and fill factor did not change before and after the lift-off process, suggesting that the lift-off process did not give any physical damage.