comCIGS - Integrative Framework of Experimental and Virtual Lab
ABSTRACT An overview is given on the present status of the comCIGS project funded by the German BMU (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit). Five partners are heading this effort which represents a framework of virtual and experimental Labs: IBM Germany, Schott AG, Helmholtz Zentrum Berlin, Universities of Mainz and Jena. All the partners have capabilities for computational Materials Science, whereas the HZ Berlin and University of Jena have pilot lines for CIGS processes. Schott AG mainly concentrates on optimization and production of specialty glass substrates for CIGS manufacturing. Aim of the project is an improvement of the overall efficiency of CIGS solar cells by replacing the presently used CdS buffer layer, optimizing CIGS layer process and using a specially designed glass substrate. As first results a number of >200 ternary alloys (Heusler phases) were identified by numerical simulation that could replace CdS based on the lattice structure and band gap. The improvement of the CIGS process itself seems to be mainly driven by the combination of a specialty glass substrate with defined TG, CTE and Na-content, together with a CIGS layer process that produces a homogeneous layer at elevated process temperatures > 600$,^circ$C. Solar cell efficiencies of η=19.2% could be obtained using process parameters that are applicable to a manufacturing environment.