Cu(In,Ga)Se2 solar cell grown on flexible polymer substrate with efficiency exceeding 17%

Development of a Cu(In,Ga)Se 2 thin film solar cell on a polyimide film with a conversion efficiency of 17.1 %, measured under standard test conditions at the European Solar Test Installation (ESTI) of the Joint Research Centre (JRC) of the European Commission, Ispra, is reported. The drastic improvement from the previous record of 14.1% efficiency is attributed to a more optimized compositional grading, better structural and electronic properties of the absorber layer as well as reduced reflection losses. Basic film and device properties, which led to the improvement in the efficiency record of flexible solar cells are presented for the new process and compared to the old process.