In most cases, glass is used to protect the active layers of the solar cells from environmental influences. In a new development, instead of working with individual glass plates, the solar cells could be printed onto a plastic film and then encapsulated with the barrier film. Being considerably lighter and flexible, plastic films make new production processes possible to enable significant reductions in manufacturing a photovoltaic module. The film and packaging developers were led by Dr. Klaus Noller along with Dr. Sabine Amberg-Schwab, as per physorg.com. Dr Sabine and her team worked almost 20 years on developing a coating material on the basis of ORMOCER that can be used as an effective barrier against oxygen and water vapor. What has been created is a barrier lacquer that the researchers combined with another known barrier material: silicon dioxide. A barrier effect that is far better than could be expected from adding only the two layers has been created. The reason for this is special effects that are generated between the two materials. For the ideal application on a film, the team in Würzburg developed an ORMOCER coating material that is easy to process and cure. The damp heat test was a particular obstacle: the cured lacquer coating must remain stable at 85 degrees Celsius and 85% humidity. The solar cells on the roof or the facade are intended to withstand extreme weather conditions and temperatures as long as possible. The team from the Freisinger Institute faced the challenge of developing a process with which the barrier layers can be applied to the film perfectly and economically. This was achieved with a roll-to-roll process. The painting line was optimized continuously to meet the special requirements: The ORMOCERs must be applied in a dust-free environment, with the layer thickness being extremely thin, yet as a continuous film. During this, the coated side must not touch one of the rollers at any time, as this would damage the layer. The patented process makes it possible to manufacture tough high barrier films in a cost-effective and environmentally friendly way. This process has already being used by industrial partners. Inorganic semiconductors are brittle, rigid materials, whose fracture limits are usually associated with strains of about 1%. However, another recent research in materials science has revealed that it is possible to combine the semiconductors with elastomeric substrates to yield systems that can tolerate strains up to several tens of percent. A group led by John A. Rogers from the University of Illinois, has developed a stretchable photovoltaic device with high areal coverage of about 70% that is composed of ultrathin GaAs solar cells on a structured polymeric substrate. The substrate surface features square islands with edge lengths of 800 µm, raised regions that are separated by trenches of 156 µm width and 200 µm depth. A mesh-like structure of GaAs solar cells that have the same size as the substrate islands and gold interconnects is deposited on the stretched substrate. After relaxation, the gold interconnects form little buckles in the trenches. The system can be twisted into complex shapes without damaging the solar cells: Upon deformation, most of the strain is taken up by the trenches, and the gold interconnects straighten; even at strains of 20%, the solar cells on the islands experience only strains of 0.22%. Compared to flexible systems with a flat, unstructured substrate, the mechanical stress for the solar cells in the new device is about eight times lower. The structure of the substrate is not limited to square islands; other lattice geometries maintain the same mechanical properties. These properties make the new design a promising candidate for flexible semiconductor devices – especially since its application is not limited to photovoltaics but can be extended to all kinds of semiconductor technologies. Ultrathin GaAs solar cells are combined with a structured stretchable substrate. This design allows for flexible devices with high areal coverage of photovoltaics. A well explored way to stretchable systems focuses on designs that allow for the rigid material to accommodate in-plane deformation through out-of-plane motion: A twisted or buckled component straightens with an applied strain. By applying this concept not to all parts of the system but only to the interconnections between active devices, the most flexible constructions are obtained. Unfortunately, the high efficacy of these designs requires a rather low areal coverage with active devices, a fact that so far has made them unfeasible for light capturing applications such as photovoltaics or photodetectors.