Flexible and monolithically integrated CIGS-Modules
- PDF / 84,866 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 76 Downloads / 225 Views
Flexible and monolithically integrated CIGS-Modules F. Kessler, K. Herz, M. Powalla, M. Hartmann1, M. Schmidt1, A. Jasenek1 and H. W. Schock1 Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung (ZSW), Hessbruehlstrasse 21c, 70565 Stuttgart, Germany 1 Institut fuer Physikalische Elektronik, Universitaet Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany ABSTRACT Monolithically integrated Cu(In,Ga)Se2-mini-modules (CIGS) have been fabricated on polymer as well as on metal foils. Preferred foils with view on costs and physical properties were ferritic steel, titanium, Fe/Ni-alloys (e.g. Kovar) and polyimide as the only appropriate low temperature candidate. The metal substrates were isolated by multiple layers of SiOx and Al2O3 which served both as diffusion barrier against substrate elements and dielectric barrier. Small area cell efficiencies of 13.8% on ferritic steel foils and 10.6% on polymer foils (both without antireflective coating) were obtained. First monolithically integrated submodules of up to 10x10cm2 substrate area were fabricated both on ferritic steel and polyimide substrates. Different patterning methods have been applied and matched to the respective substrate materials. INTRODUCTION Although the world-wide PV production in 2000 increased from 201.3 MW in 1999 to more than 288 MW [1], the demand is higher than the supply at present. The PV acceptance of consumers and architects is growing continuously and building integrated systems with a high aesthetic performance play an increasing role. Multiple functions such as semi-transparency and shadowing as well as facade integration enjoy great popularity but are not necessarily qualified for any PV cost reduction. Additional interesting and novel applications are expected from thin and bendable modules especially in the area of space, aeronautic and mobile applications. Several efforts have been reported within the past years on the development of flexible and lightweight Cu(In,Ga)Se2 (CIGS) modules [2-6], especially from the USA. Both the US and European activities were encouraged from relatively high small area cell efficiencies obtained on metallic as well as on polymer substrates aiming at high power densities of > 1kW/kg. An efficiency of η = 12.8% was reported [4] on a 20µm thin polyimide film and even η = 17.1% could be achieved on stainless steel substrates [2]. Nevertheless cell and module results on foils are still lower than on glass substrates. The fabrication of monolithically interconnected modules on foils is a big challenge and the high power-to-weight ratios calculated still have to be demonstrated on large areas. Various materials and material classes such as ceramics, metals and polymers were evaluated at ZSW and IPE to find appropriate foils fulfilling both technological and economic requirements. The device and layer quality is strongly influenced by the substrate material and surface morphology, especially on large areas. The combination of high chemical stability, extremely smooth surface, well matched thermal expansion coe
Data Loading...
