Outdoor Stability Testing of Printed Organic Solar Cells for Indoor Applications

Abstract: Renewable energy is required for a sustainable future and one way to meet this is with organic solar cells (OSCs). The OSC can be easily manufactured at a low cost, be lightweight and be used on flexible surfaces. If the efficiency in high illumination intensities and stability in harsh environments increase for OSCs, they can com- pete with the other technologies even in outdoor conditions. Another advantage of OSCs is their good performance under low-light and indoor conditions. This is utilized by Epishine, a Swedish company based in Linköping working with small, thin and flexible organic printed solar cells optimized for indoor applications. The goal of this thesis is to determine how Epishine’s solar cells for low-light indoor usage work in more challenging conditions and to identify which are the factors that are detrimental for the lifetime of the cells. The result showed that all modules had a similar initial electrical performance which indicates that the modules have high reproducibility and degradation in darkness is negligible (since the initial measurements were made at different times). The tests showed that the temperature affected the modules. The test in the oven showed a little less than half the degradation compared to tests under the solar simulator, although both tests were subjected to the same temperature. The hu- midity test and the test exposed to LED-light showed almost no degradation. For the levels exposed to the sun or simulated sunlight, the decrease of the short circuit current density shows a burn-in time, which is typical for organic solar cells. After the first couple of hours, the decrease slows down to a more linear behaviour. All modules that were exposed to bright light also showed some recovery effect for short circuit current density and efficiency after they have been kept in the dark. It would be interesting to investigate the behaviour of the modules after even more exposure and look into how the recovery effect works.