No abstract

The lifetime and stability of organic photovoltaics (OPVs) are the key factors that influence the technology used to scale up and commercialize OPVs. High-performing and reliable devices are used to fabricate the devices of choice. Materials and methods that can be used to prevent the degradation of organic materials, enabling better OPV applications, are being increasingly researched in recent years. Herein, we present the surface modification process of a commercial, flexible barrier film based on polyethylene terephthalate (PET). A sol-gel deposition method was used to modify the surface. Two scalable coating techniques, spray- and bar-coating, were investigated as the processing methods. Treated films were optically, morphologically, and topologically characterized. The modification of the barrier film surface increased the surface hydrophobicity of the bar-coated and spray-coated treated films. This was validated by the contact angle measurements. OPV roll-to-roll (R2R) mini-modules with 4.2% power conversion efficiency were fabricated and encapsulated with the treated films. The lifetime and stability were assessed by conducting accelerated aging tests based on the ISOS-D-3 protocol. The spray-coating technique provided a more stable layer than the bar-coating technique, and the lifetime of the OPV modules encapsulated in spray-coated treated barrier films was increased. Surface modification has been demonstrated to be a promising approach for not only improving the barrier film properties (resulting in the improved lifetimes of the modules) but also reducing the extents of reflectance losses in the OPV modules post encapsulation.

Solar photovoltaic (PV) cells allow the direct conversion of sunlight into electricity without CO2 emission. Finding a way to cheaply utilize the vast amount of solar energy is one of the biggest challenges for this technology. The organic photovoltaic cells (OPV) are based on solution-processed photoactive polymers and can be fabricated via roll-to-roll (R2R) processes, which allow high production throughput with low costs. CSEM Brasil is building the foundations of future high-tech industries in Brazil and one of our key technology development areas is OPV modules production using R2R coating. In this work, polymer solar cells based on P3HT: PC[60]BM were prepared by R2R coating (electron transport, active and hole transport layers – ETL, AL and HTL) and by screen printing (top silver electrode). In order to save material and give more transparency of the OPV module were compared and evaluated the performance of two different suppliers of Ag paste (A and B) in three different top contact configurations, solid, grid and honeycomb. Additionally, were compared two different screen suppliers (I and II) for screen printing process and the Ag paste drying time studied. The comparisons were made with modules with an active area of 21.6 cm2 (6 stripes serially connected). Photovoltaic performance was evaluated in terms of Ag paste and screens suppliers, Ag pattern and drying time. Finally, modules were encapsulated in a R2R laminator using a flexible barrier film and evaluated in terms of lifetime.