Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
DOI: https://doi.org/10.29363/nanoge.hopv.2020.076
Publication date: 6th February 2020
In the field of photovoltaics, the recent concept of perovskite solar cells has attracted great interest due to their high efficiency combined with a potential low cost and good versatility. One of the main remaining challenges now concerns their intrinsic stability. There is a vital need for a better understanding of the degradation mechanisms and thereby the possible mitigation strategies. The presented work focuses on degradation mechanisms taking place in the double cation perovskite solar cells. The studied perovskite is the following: FA0,95Cs0,05Pb(I0,83Br0,17)3. This material is well known for its high and stabilized performances [1,2]. In order to validate the enhanced stability of mixed cation perovskite compared to the common MAPbI3 monocation one, ageing tests were conducted using an innovative device architecture compatible with both low temperature processes and semi-transparent devices for tandem cells development.
The conducted experiments are resumed on figure 1. Three conditions were tested to study the precise impact of each possible constraint: temperature, oxygen and humidity. Thanks to an optimized characterization set composed of X-ray diffraction, UV-visible absorption, photoluminescence, FTIR spectroscopy, power conversion and external quantum efficiencies, interlinked with special resolved mapping techniques such as photoluminescence and light beam induced current imagings and RGB analysis, the global degradation behaviour of mixed cation perovskite was draft. Ageing of partial stacks was also conducted in order to confirm obtained results. Interesting results such as the good humidity tolerance of the material were obtained. Under drastic conditions (85°C/Air/40%RH), even if an important loss of photovoltaic properties (62%) occurred during the first 150h, the performances were then exceptionally stabilized for more than 500h with a 5.2% power conversion efficiency.