Flexible and monolithically integrated CIGS-Modules

The Effect of Film Composition on the Texture and Grain Size of CuInS2 Prepared by Chemical Spray Pyrolysis

Ternary single-source precursors were used to deposit CuInS2 thin films using chemical spray pyrolysis. We investigated the effect of the film composition on texture, secondary phase formation, and grain size. Films with either (112)- or (204/220)-preferred orientation were deposited with most often In-rich composition. The (112)-preferred orientation became more pronounced as the film composition became more In-poor. Films with a (204/220)-preferred orientation were both In-rich and contained a yet unidentified secondary phase. The phase was evaluated as an In-rich compound based on composition analysis and Raman spectroscopy. Further experiments showed that the phase could be removed by depositing a thin Cu layer prior to the growth of CuInS2. Similarly, as-grown Cu-rich (112)-oriented films did not exhibit the In-rich compound. The (204/220) preferred orientation of the film is likely related to the equivalent symmetry between planes of CuInS2 and the In-rich compound. The largest grain size (∼ 0.5μm) was achieved with Cu-rich (112)-oriented films.

Current Status and Future Prospects of CISCuT Based Solar Cells and Modules

CISCuT - CIS on Cu-Tape - has been established as a new thin film technology, in which Cu/In/S based solar cells are continuously fabricated on a Cu-tape in a series of consecutive roll-to-roll processes. Flexible modules encapsulated into polymer foils are assembled by interconnecting stripes of this tape cell in a roof-tile manner in an automated assembly line. J-V characteristics that show efficiencies of 9 % so far and that have been certified by the Frauenhofer Institut Solare Energiesysteme are presented. Stability tests over more than 8000 hours show promising results. Best results obtained from cells and from modules that have automatically been assembled to different areas are compared. This comparison gives insight into how the different roll-to-roll processes including the assembling of the module influence the overall quality of the module. Latest results including the unique mechanical properties of CISCuT-based solar cells and modules are highlighted. An outlook on the future prospects of this exciting technology is given.