Summary of the project
Flexible photovoltaics based in thin film Cu(In,Ga)Se2 (CIGS) technologies can largely contribute to the fast penetration of solar energy production in residential and low weight infrastructures applications. These flexible devices can reduce the weight of a conventional glass-glass solar panel in almost one order of magnitude, representing a clear advantage for their application in building integrated concepts. Nevertheless, for a cost-competitive full market entry, flexible CIGS photovoltaic (PV) technologies require the availability of innovative encapsulation solutions with both, very low costs and excellent barrier properties guaranteeing a long operating time of the devices, while keeping the lightweight characteristics. Even if there are already existing solutions with acceptable performance levels, costs remain a relevant issue that needs to be solved in order to keep the stringent cost reduction targets established for these technologies. To solve these problems, DURACIS will explore new alternative encapsulation and optical glue materials and concepts, compatible with their implementation into already existing industrial CIGS pilot lines and allowing a significant extension of the lifetime while substantially reducing costs. To achieve this goal, transfer of concepts previously developed for organic technologies (with very stringent encapsulation requirements) will be investigated. In particular, three innovative approaches will be fully developed and tested, including:
i. Liquid encapsulant based strategies that have been previously developed and applied in OLED technologies;
ii. Self-stratifying polymers concepts that have been developed for encapsulation of organic PV (OPV) devices;
iii. Alternative front sheet and Polyolefin embedding encapsulant concepts.
The final goal of DURACIS is the development of a novel encapsulation technology with costs below 15 Euros/m2 and ensuring a durability higher than 25 years for flexible CIGS devices. The project will adopt a global strategy including solutions for the main industrial substrate technologies that have been developed for flexible CIGS (polyimide, steel substrates) and will also include the analysis of their transfer into industrial pilot lines available in the consortium. The implications of the different kinds of substrates on these new encapsulation concepts will be specifically addressed aiming at the development of optimized cost efficient solutions compatible with very long term stability.
The project will also include the development of advanced methodologies for the non-destructive monitoring of the encapsulation processes and layers. In particular, IREC will work in the development of optical methodologies (Raman scattering, photoluminescence, reflection based methodologies), to assess and provide fast and reliable tools for control and monitoring of the degradation of the different encapsulant solutions proposed in DURACIS. This involves both monitoring of the deposition processes as well as the definition of fast methodologies for detection of potential degradation effects affecting the encapsulation and device lifetime.
DURACIS is coordinated by the Solar Energy Materials & Systems (SEMS) group from IREC and has involved a strong inter-sectoral and interdisciplinary consortium including research groups from ZSW (Germany), IPVF (France), Univ. of Innsbuck (Austria) and relevant companies from the Organic chemistry, Energy and Photovoltaic sectors as Ecopol Tech (Spain), AC&CS (Belgium), Eliosys (Belgium), EDF R&D (France), Sunplugged (Austria) and Lenzing Plastics (Austria).