Perovskite solar cells under protons irradiation: From in-situ IV-monitoring to root cause degradation elucidation

In recent years, the mixed halide Perovskite Solar Cells (PSCs) triggered huge amount of R & D activities, thanks to their excellent optoelectronic properties, fast progressing power conversion efficiencies and low cost potential. On top of that, with their high specific power & compatibility with flexible substrate, PSCs appear as a promising mid/long-term alternative photovoltaic technology for space applications. However, the harsh space environ-ment requires particularly robust PV solutions, especially against electrons & protons irradiations; detailed evaluation and comprehension of ageing under irradiations are thus key steps on PSCs development path. In this paper, we focus on perovskite materials and subsequently solar cells proton radiation hardness, with a fluence up to 5 x 1014 protons/cm2 at 1 MeV. Optical, microstructural and electrical characterisations, both in-situ and ex-situ, are used to track the evolutions of 4 different perovskite stoichiometries under irradiation. To this end, single layers, sub-assemblies and full solar cells stack were exposed to protons flux. This systematic approach allowed us to highlight the differences in radiation hardness of PSCs constituting layers: the photo-active Cs0.05FA0.95Pb(I1-xBrx)3 materials exhibits outstanding radiation hardness under the tested conditions, while the PTAA Hole Transport Layer (HTL) appears as a weak contact layer driving cells performance degradation at high fluences.