Thin film tandem solar cells, comprising of a perovskite top device and a radiation hard CIGS bottom solar cell would be attractive for space applications since they can be lightweight, flexible, and efficient. In this work, the ability to withstand the harsh radiation environment in space, consisting mainly of high-energy protons is demonstrated. In-situ measurements of the J-V characteristics during proton irradiation with a proton energy of 68 MeV show that organic-inorganic perovskites are radiation hard. The investigated CH3NH3PbI3 based perovskite solar cells possess a negligible degradation for proton doses of up to 1012 p cm-2. [1,2]This exceeds the proton dose at which c-Si degrades by almost 3 orders of magnitude. Even more surprising is the observation that the solar cell performance improves with time after the proton irradiation is terminated. Hence, the localized defects caused by proton irradiation are metastable and vanish with time. In addition, proton irradiation partially compensated the photo-degradation effect of the perovskite solar cells. Compared to untreated devices the open circuit voltage and the fill factor improved. This is mainly attributed to smaller recombination losses due to a decrease of the density of localized defects. Simultaneously, proton irradiation caused the formation of shallow defects, which act as doping centers. The observed radiation hardness and self-healing capabilities render inorganic-organic perovskite absorbers highly attractive for space applications.
 F. Lang, N. H. Nickel, J. Bundesmann, S. Seidel, A. Denker, S. Albrecht, V. V. Brus, J. Rappich, B. Rech, G. Landi, H. C. Neitzert, Adv. Mater. 2016, 28, 8726.
 V. V Brus, F. Lang, J. Bundesmann, S. Seidel, A. Denker, B. Rech, G. Landi, H. C. Neitzert, J. Rappich, N. H. Nickel, Adv. Electron. Mater. 2017, 3, 1600438.