Cheaper and more efficient flexible photovoltaics
Development of efficient PV cells is high on the EU Strategic Research Agenda (SRA). But for widespread market acceptance, the deployed technologies must be low cost and suitable for mass production. Therefore, the R2R-CIGS (Roll-to-roll manufacturing of high efficiency and low cost flexible CIGS solar modules) project developed and scaled-up roll-to-roll (R2R) processes to manufacture copper indium gallium selenide (CIGS) alloy based PV modules on a polymer substrate. This can enable further cost reductions compared to standard silicon technologies. Another benefit is that the modules are flexible and lightweight and can be fitted to irregular surfaces such as building walls. The ambitious target production costs set by R2R-CIGS are achievable when efficiencies of flexible solar cells are compared to those based on glass substrates. Power conversion module efficiencies of as much as 16 % can be expected. R2R-CIGS has improved state-of-the-art CIGS solar cells by modifying the structural, chemical and electrical characteristics at the nano-scale range. A vacuum based co-evaporation process was developed and up-scaled for R2R deposition of a nano-graded CIGS energy conversion layer on polymer foil. An innovative process using R2R atomic layer deposition (ALD) allowed to make cadmium-free buffer layers. The project also developed a R2R automated laser scribing process of thin-film layers on polymer substrates, which enabled monolithically interconnected flexible solar modules. In addition, scientists integrated a plasma-enhanced CVD injector into an industrial CVD reactor and installed new equipment for DC sputtering in a R2R pilot line. The consortium also explored different ways for developing moisture barrier coatings to ensure flexible solar modules and water-sensitive flexible products. R2R-CIGS accelerated the market introduction of flexible CIGS modules by providing industrial scale processes and equipment solutions. These are used for the production of highly efficient, low cost and lightweight CIGS modules. The polyimide substrate enabled the integration of CIGS modules in low cost and light weight building components and transport applications. The technologies and processes developed by R2R-CIGS can also be applied to the manufacturing of large area flexible electronics, lighting and displays.
Keywords
Photovoltaic, flexible, roll-to-roll, solar, module, manufacturing, atomic layer deposition.
