A europium shuttle for launching perovskites to space: using Eu2+/Eu3+ redox chemistry to boost photostability and radiation hardness of complex lead halides

Abstract

Perovskite solar cells have already demonstrated high radiation hardness substantially exceeding that of crystalline silicon and GaAs based solar panels commonly used in space. However, aerospace applications of PSCs require a number of other important prerequisites, among which the stability towards a combination of multiple stress factors characteristic of the outer space environment is of particular importance. Herein, we present an in-depth investigation of the influence of the Eu²⁺/Eu³⁺ redox pair on the intrinsic photostability of PbI₂ and complex lead halides. We confirm that the incorporation of europium effectively suppresses the photochemical production of metallic lead and other aging products. Furthermore, the Eu-modified methylammonium-free double cation perovskite formulation Cs_0.12FA_0.88Pb_0.99Eu_0.01I₃ demonstrated excellent radiation hardness under exposure to ultrahigh doses of gamma rays (5.5 MGy) and 8.5 MeV electron beams (fluences up to 3 × 10¹⁶ e per cm²) owing to the mitigated aging pathways such as radiochemical Pb⁰ formation and segregation of CsPbI₃ and/or FAPbI₃ δ-phases. Thus, the stabilizing effect of the Eu²⁺/Eu³⁺ redox shuttle was exploited here for the first time to substantially increase the stability of perovskite absorber materials with respect to three different stress factors simultaneously: light, gamma-rays and high-energy electrons. Further development of this research direction might facilitate commercialization of PSCs for aerospace applications.