# The pursuit of stability in halide perovskites: the monovalent cation and the key for surface and bulk self-repair

Source: [The pursuit of stability in halide perovskites: the monovalent cation and the key for surface and bulk self-repair](<https://www.sota2.com/research/paper/68fa3ce61e209131ce8de491>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-25T01:22:56.037Z

Authors: D R Ceratti, A V Cohen, R Tenne, Y Rakita, L Snarski, L Cremonesi, I Goldian, I Kaplan-Ashiri, T Bendikov, V Kalchenko, M Elbaum, M A C Potenza, L Kronik, G Hodes, D Cahen

Published: 2020-09-30T12:42:18.000Z

## Abstract

We find significant differences between degradation and healing at the surface or in the bulk for each of the different APbBr3 single crystals (A=CH3NH3+, methylammonium (MA); HC(NH2)2+, formamidinium (FA); and cesium, Cs+). Using 1- and 2-photon microscopy and photobleaching we conclude that kinetics dominate the surface, and thermodynamics the bulk stability. Fluorescence-lifetime imaging microscopy, as well as results from several other methods, relate the (damaged) state of the halide perovskite (HaP) after photobleaching to its modified optical and electronic properties. The A cation type strongly influences both the kinetics and the thermodynamics of recovery and degradation: FA heals best the bulk material with faster self-healing; Cs+ protects the surface best, being the least volatile of the A cations and possibly through O-passivation; MA passivates defects via methylamine from photo-dissociation, which binds to Pb2+. DFT simulations not only provide insight into the latter conclusion, but also show the importance and stability of the Br3- defect. These results rationalize the use of mixed A-cation materials for optimizing both solar cell stability and overall performance of HaP-based devices, and provide a basis for designing new HaP variants.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2009.14617>)

[PDF](<https://arxiv.org/pdf/2009.14617.pdf>)