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Mixed organic–inorganic halide perovskite-based solar cells have attracted interest in recent years due to their potential for both terrestrial and space applications. Analysis of interfaces is critical to predicting device behavior and optimizing device architectures. Most advanced tools to study buried interfaces are destructive in nature and can induce further degradation. Ion beam techniques, such as Rutherford backscattering spectrometry (RBS), is a useful non-destructive method to probe an elemental depth profile of multilayered perovskite solar cells (PSCs) as well as to study the inter-diffusion of various elemental species across interfaces. Additionally, PSCs are becoming viable candidates for space photovoltaic applications, and it is critical to investigate their radiation-induced degradation. RBS can be simultaneously utilized to analyze the radiation effects induced by He+ beam on the device, given their presence in space orbits. In the present work, a 2 MeV He+ beam was used to probe the evidence of elemental diffusion across PSC interfaces with architecture glass/ITO/SnO2/Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3/spiro-OMeTAD/MoO3/Au. During the analysis, the device active area was exposed to an irradiation equivalent of up to 1.62 × 1015 He+/cm2, and yet, no measurable evidence (with a depth resolution ∼1 nm) of beam-induced ion migration was observed, implying high radiation tolerance of PSCs. On the other hand, aged PSCs exhibited indications of the movement of diverse elemental species, such as Au, Pb, In, Sn, Br, and I, in the active area of the device, which was quantified with the help of RBS. 

The high tolerance and stability of triple halide perovskite solar cells is demonstrated in practical space conditions at high irradiation levels. The solar cells were irradiated for a range of proton energies (75 keV, 300 keV, and 1 MeV) and fluences (up to 4 × 1014 p/cm2). The fluences of the energy proton irradiations were varied to induce the same amount of vacancies in the absorber layer due to non-ionizing nuclear energy loss (predominant at <300 keV) and electron ionization loss (predominant at >300 keV). While proton irradiation of the solar cells initially resulted in degradation of the photovoltaic parameters, self-healing was observed after two months where the performance of the devices was shown to return to their pristine operation levels. Their ability to recover upon radiation exposure supports the practical potential of perovskite solar cells for next-generation space missions.