Trapped-Hydrogen-Induced Energy Loss in Tin-Based Hybrid Perovskite Solar Cells

Abstract

The hitherto subdued power conversion efficiencies of Sn-based hybrid perovskite solar cells are generally attributed to severe nonradiative recombination; however, the responsible deep-level defects are still unclear. Here, we report an important nonradiative energy loss mechanism in the prototypical FASn⁢I3 [FA = HC⁢(NH2)2, formamidinium]. High-density tin vacancies (𝑉Sn) can effectively capture hydrogen to form 𝑉Sn −H2 complexes that act as highly detrimental nonradiative recombination centers. We quantitatively show that they can give rise to strong carrier recombination and thus energy loss due to a high nonradiative recombination rate constant. These key findings identify a hidden yet critical origin for the low performance of FASn⁢I3-based devices and highlight the significance of controlling the hydrogen environment in the development of broad high-efficiency nontoxic halide perovskite device applications.