Visitors to LOPEC in Munich, Germany were able to marvel at organic photovoltaic from the roll. In the future, a new power foil may be able to provide electricity as well as shade at bus stops, on shed roofs, and carports.
A six meter long, 50 centimeter wide solar module made from flexible, organic photovoltaic material was one of the things to marvel at during the recent LOPEC in Munich. Produced completely using a roll-to-roll process, the organic solar cells also need absolutely no indium tin oxide (ITO) as an anode material, which, as we all know, is rare and expensive. The power film is the result of the FabriGen European research project. The main focus for the six partners from four countries was to use membrane architecture.
The initiator of the project was Robert Carpenter, Managing Director of Inside2Outside, a UK-based SME. His textile membrane structures equipped with solar cells are designed to be fitted to large areas with flexible plastic structures that are well below the price and weight of glass roofs. The main focus is architectural areas, such as shading systems for pedestrian precincts, bus stops, shed roofs and carports.
Organic photovoltaic teamwork
The prototypes took just six months to produce and involved some real teamwork. This included vacuum processing of the metal electrode at the Centre for Process Innovation (CPI), coating the organic semiconductor at the Fraunhofer ISE, printing the silver pathways and lamination at Coatema, and high-frequency welding of the solar film on to the textile membrane at I2O. The solar cell structure and module design were developed by Fraunhofer ISE.
The scientists in Freiburg, Germany were also involved in developing the encapsulation, which took place at CPI in the UK. All the partners in the project were involved in integrating the organic photovoltaic system on to a fabric membrane, but especially CPI and the project coordinator Inside2Outside Ltd. (I2O). Coatema Coating Machinery GmbH in Germany was responsible for developing the large-scale lamination process. It may be a few years until the films are ready for the market.
Solar film number 2
Another fully flexible solar module from Fraunhofer ISE with an area of about 90 square centimeters also works without indium tin oxide (ITO). All the layers, with the exception of the metal electrodes, were produced on this system at Fraunhofer ISE. The silver fingers for the contacts on the front were applied with screen printing in cooperation with and in the pilot facility of the institute’s industrial partner Thieme. The module is sealed with a barrier film and is thus fully flexible. The cells in the module have passed the damp heat test for thin-film photovoltaics. In this test, solar cells or modules are tested for 1000 hours at 85°C and 85% relative humidity.
During this accelerated aging test, the output of the organic photovoltaic cells deteriorated by less than five percent. Fraunhofer ISE already believes in the long-term stability of the cells, predicting eight or more years. Yet another important step towards product maturity for this form of solar cell technology.