Flexible Cu(In,Ga)Se/sub 2/ solar cell for space applications

Light weight, flexible, thin film solar cell modules are an attractive alternative to more established space PV technologies. In a research cooperation, the Hahn-Meitner- Institut and Dutch Space are currently developing a Cu(In,Ga)Se/sub 2/ based thin film solar cell on a flexible titanium substrate. Absorber layer preparation is based on the three-stage co-evaporation recipe combined with a new optical in-situ process control (diffuse laser light scattering). Small area AM 1.5 efficiencies of 16.5% (glass substrate) and 15.0% (titanium foil) could be reached without antireflection coating. On a large area (20 cm) an efficiency of 10.2% has been achieved. The lower efficiency with respect to small cells is mainly due to localized leakage currents, infrared thermography is applied in order to study effects of layer non-uniformity on thin film solar cell devices. Arrays of small area cells have been prepared for investigating spatial inhomogeneities of PV-parameters across 5/spl times/5 cm/sup 2/ Ti-foil substrates.