ECN publication
PROCIS : product identification, pilot plant design and market potential evaluation for copper indium disulphide (CuInS2) on copper tape substrates: publishable report
Wienke, J.A.; Winkler, M.; Burgelman, M.; Vleuten, P. van der
Published by: Publication date:
ECN Solar Energy 1-5-2002
ECN report number: Document type:
ECN-C--02-052 ECN publication
Number of pages: Full text:
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The new, innovative IST-technology for copper indium disulphide (CuInS2)solar cells on copper tapes (CISCuT) is a cost-effective series of consecutive roll-to-roll processes. One major feature of this technology is the multifunctionality of the copper tape (1 cm in width), serving as mechanical carrier, source for in-line CIS-formation and back contact of the solar cell, another is the potential to make flexible cells and modules. During the PROCIS project, the CISCuT technology has been further developed to a baseline for CuInS2 solar cell fabrication. In this sense, a major project effort has been the up scaling from the manually produced 2 mm2 dot cells at the beginning to large area tape (up to 10 cm in length). For the definition of the baseline equipment a comprehensive characterisation and modelling of CuInS2 material has been carried out. It was found that with standard processing conditions (a copper band speed of 3-4 cm/s and a temperature of 550 °C for the sulphurisation step) CuInS2 with an internal p-n junction is produced. This material consists of various Cu-In-S phases with the result that the photoelectrical properties of ?as-grown? CISCuT material differ from conventional CIS layers. Therefore, it requires different charge collecting layers with fortunately no need for the usually applied (toxic) CdS layer. The Cu/CuInS2/CuI/ZnO:Al configuration was selected as most promising in two aspects: the deposition equipment needed for the involved collecting layers could be integrated in the roll-to-roll technology and, with this cell concept the highest cell efficiency ( = 5.4 % on 400 mm2) is achieved. In parallel, a simpler Cu/CuInS2/CuI/metal grid configuration was investigated. In this case, the metal grid replaces the ZnO:Al window layer. However, the up scaling of this cell concept is still in its infancy. Intensive research has been done to find suitable contacting and interconnection technologies. As a result, roof-tile integrated modules with maximum dimensions of (10x20) cm2 and 10 V output have been produced. The favourable flexibility of the copper tape material could be retained in the module by using specific contacting/lamination methods. Preliminary stability and climate tests have been carried out on CISCuT devices. The results indicate that laminated devices are stable under continuous illumination at room temperature. Humidity in combination with high temperature (85 %, 85 °C) however resulted in delamination and cell corrosion. Therefore, improvement in lamination technology is urgently needed. A good understanding of device physics could be obtained by extension of standard measurement techniques with Light Beam Induced Current (LBIC) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), Parallel Resistance Analysis by Mapping of Potential (PRAMP) and thermography measurements.

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