R2R-Cigs Project Develops Roll to Roll CIGS PV Process
The lightweight and low cost nature of flexible copper indium gallium (di) selenide (CIGS) photovoltaic cells makes them attractive for use in a number of energy harvesting applications in the built environment, such as shading elements and industrial roofing. However the technology is not yet in the mass market as developmental progress is needed to produce flexible CIG modules that meet the price points, manufacturing volumes, and cell efficiency requirements that industry desires.
R2R-CIGS was a European, industry-led collaborative project which looked at overcoming these barriers to commercialisation by developing cost-effective, roll to roll processes and technologies for the continuous, high-volume manufacture of flexible CIGS photovoltaics. The project ran from April 2012 to September 2015 and included CPI alongside 9 partner organisations from Austria, Finland, Germany, the Netherlands, Spain, Switzerland and the UK.
R2R-CIGS used high-efficiency, thin-film CIGS absorber material on flexible polymer substrates and compared their performance to existing modules on glass substrates. The consortium demonstrated 20% cell efficiency and 16% module efficiency on flexible substrates. R2R-CIGS also established pilot scale roll to roll manufacturing processes and developed new materials with improved moisture barrier performance and reduced environmental impact.
The technical achievements realised during the project are summarised below:
- Multi-stage CIGS co-evaporation process for record cells transferred to an in-line roll to roll reactor
- Roll to roll spatial atomic layer deposition, chemical batch deposition and evaporation deposition processes and tools for cadmium free buffer layers
- Roll to roll deposition of transparent conductive pxide (TCO) front electrodes
- Roll to roll automatic laser scribing for monolithic interconnection
- Encapsulation and moisture barriers for flexible CIGS cells using roll spatial atomic layer deposition technology.
CPI’s contribution to R2R Cigs
CPI developed barrier layers to protect the cells from moisture and oxygen ingress; both as part of the transparent, weatherproof front-sheet, and as direct encapsulation on to the CIGS cells. CPI also managed the exploitation planning, IPR management and dissemination activities.
For the front-sheet materials, initially using our Beneq WCS600 roll to roll ALD coater, CPI produced large areas of barrier materials with a water vapour transmission rate (WVTR) in the 10^-3 g/m2/day range. During the project, with further process optimisation by CPI and Beneq, the tool produced ultra-barrier materials with WVTR performances of <10^-4 g/m2/day on PET film with 20 nm of AlOx at 1 m/min and 0.5 m wide.
Direct encapsulation work was also carried out. This was performed on 4 substrate types: CIGS modules on glass made by ZSW (100×100 mm) and Manz (300×300 mm) which were processed in batch using the roll-to-roll spatial ALD tool on flexible conductor material, and full CIGS cells made by project partner Flisom. The large glass cells and roll to roll cells are undergoing extended damp heat testing, but the smaller cells were shown to pass 1,000 hours damp-heat testing at 85 °C, 95% relative humidity with greater than 90%, and 2,000 hours with over 70% of the original efficiency.
- CPI – United Kingdom | Empa – Switzerland
- Flisom – Switzerland | ISOVOLTAIC AG – Austria
- Manz CIGS Technology – Germany | ZSW – Germany
- Mondragon Assembly – Spain | Beneq – Finland
- VDL – The Netherlands | TNO – The Netherlands
R2R-CIGS was a project of the European Union Framework Programme 7(FP7/2007 – 2013) under grant agreement 283974.
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