Energy-Independent Barrier Strategy Stabilizes Proton-Irradiated Perovskite Solar Cells against Outgassing

Abstract

Perovskite solar cells (PSCs) have emerged as promising candidates for space photovoltaics, due to their high power-per-weight ratio. However, the space environment imposes harsh requirements, such as radiation tolerance. Especially, proton radiation induces defects in solids, reducing the lifetime of devices. While encapsulation can reduce damage, cover glasses are incompatible with the desirable development of flexible solar cells. Here, a thin-film encapsulation of ALD-AlOx is tested as an outgassing barrier against different space-relevant proton energies, i.e., 0.05, 1, and 3 MeV, with a fixed fluence of 5 × 1012 p+/cm2. While simulations confirm that even low-energy protons can easily overcome the barrier, the encapsulant works by preventing the outgassing of organic components displaced or thermally volatilized by protons. Thus, a detrimental increment of the PbI2 moiety within the perovskite absorber is prevented. The retained performance was improved from as low as 71% (unprotected devices) to as high as 99% (encapsulated).