Solar cells made of silicon have been around for 70 years. Organic solar cells, on the other hand, are quite new, but open up new possibilities for emission-free electricity production. These solar cells made of organic compounds achieve efficiencies of up to 19 percent, yet they are extremely thin, light and flexible. Applied to transparent film, they can be used in a wide variety of geometric shapes and colours in areas for which silicon-based solar cells are unsuitable. One problem so far, however, has been their short lifespan: organic solar cells deteriorate quite quickly, which is why they are still of little commercial importance. This is now to change: Under the leadership of Graz University of Technology (TU Graz), the "OPVStability" network brings together international partners from science and industry who will be conducting research over the next four years to increase the durability of organic solar cells. The European Commission is funding the project with around 2.7 million euros.
Ten research institutes across seven countries
"There are thousands of material combinations that can be used to produce organic solar cells," says project director Gregor Trimmel from the Institute for Chemistry and Technology of Materials at TU Graz. "We want to find out which of them are the most suitable: i.e. particularly durable and yet efficient in terms of electricity output." Ten research institutes in seven countries will each create a PhD position in the next few months to drive forward the development work in cooperation with the industry partners InfinityPV, ASCA and Sunnybag. "In principle, organic photovoltaic cells have the potential to produce electricity at similarly low costs as silicon-based products," says Trimmel.
Analysis of decomposition
The researchers want to study the decomposition processes of various potentially suitable materials in detail. For this purpose, the organic compounds are exposed to artificial sunlight in the laboratory, but also tested under real weather conditions in Europe as well as the Negev desert. The precise analysis of gradual degradation is a challenge: "Organic solar cells are no more than 200 nanometres thick. To be able to isolate decomposition products in them, very special methods and instruments are needed," Trimmel explains. Furthermore, the researchers are using approaches based on artificial intelligence and machine learning to analyse the large amounts of data that are generated in high-throughput experiments. The results of the investigations will allow detailed deductions of the chemical decomposition processes. In addition to the physical tests, digital simulations of chemical compounds will be run to find the most suitable materials for the next generation of organic photovoltaic cells.
The OPVStability network partners
In addition to TU Graz, the OPVStability network includes Johannes Kepler University Linz, Consejo Superior de Investigaciones Científicas, Ben-Gurion University of the Negev, University of Potsdam, Karlstad University, Central European Research Infrastructure Consortium, University of Bayreuth, Friedrich Alexander Universität Erlangen Nürnberg, University of Southern Denmark as well as the associated partners InfinityPV, ASCA GmbH, Universitat Autonoma de Barcelona, Sunnybag GmbH, Zentrum für Elektronenmikroskopie, and Forschungsverbund Berlin e.V.
This research is anchored in the Field of Expertise "Advanced Materials Science", one of five strategic foci of TU Graz.