Published February 23, 2023 | Version Accepted version
Journal article Open

Probing Proton Diffusion as a Guide to Environmental Stability in Powder-Engineered FAPbI3 and CsFAPbI3 Perovskites

  • 1. BCMaterials, Basque center for Materials
  • 2. École Polytechnique Fédérale de Lausanne
  • 3. Univ. Bordeaux, CNRS, Bordeaux INP, ENSCBP, IMS, CNRS UMR 5218, F-33400 Talence, France
  • 4. Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33405, Talence, France

Description

Formamidinium lead iodide-based solar cells show promising device reliability. The grain imperfection can be further suppressed by developing powder methodology. The water uptake capability is critical for the stability of α-formamidinium lead triiodide (FAPbI3) thin films, and elucidating the migration of hydrogen species is challenging using routine techniques such as imaging or mass spectroscopy. Here, we decipher the proton diffusion to quantify indirect monitoring of H migration by following the N–D vibration using transmission infrared spectroscopy. The technique allows a direct assessment of the perovskite degradation associated with moisture. The inclusion of Cs in FAPbI3, reveals significant differences in proton diffusion rates, attesting to its impact. CsFAPbI3’s ability to block the active layer access by water molecules is five times higher than α-FAPbI3, which is significantly higher than methylammonium lead triiodide (MAPbI3). Our protocol directly probes the local environment of the material to identify its intrinsic degradation mechanisms and stability, a key requirement for optoelectronic applications.

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Funding

European Commission
MOLEMAT - Molecularly Engineered Materials and process for Perovskite solar cell technology 726360