Issue 5, 2021

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

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 provide insight into the passivating role of MA, and also indicate the importance of the Br3 defect as well as predicts its stability. The occurrence and rate of self-healing are suggested to explain the low effective defect density in the HaPs and through this, their excellent performance. 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.

Graphical abstract: The pursuit of stability in halide perovskites: the monovalent cation and the key for surface and bulk self-healing

Supplementary files

Article information

Article type
Communication
Submitted
02 Jan 2021
Accepted
11 Mar 2021
First published
12 Mar 2021
This article is Open Access
Creative Commons BY license

Mater. Horiz., 2021,8, 1570-1586

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

D. R. Ceratti, A. V. Cohen, R. Tenne, Y. Rakita, L. Snarski, N. P. Jasti, L. Cremonesi, R. Cohen, M. Weitman, I. Rosenhek-Goldian, I. Kaplan-Ashiri, T. Bendikov, V. Kalchenko, M. Elbaum, M. A. C. Potenza, L. Kronik, G. Hodes and D. Cahen, Mater. Horiz., 2021, 8, 1570 DOI: 10.1039/D1MH00006C

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