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Halide Remixing under Device Operation Imparts Stability on Mixed-Cation Mixed-Halide Perovskite Solar Cells.

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Gałkowski, Krzysztof  ORCID logo
Abfalterer, Anna 


Mixed-halide mixed-cation hybrid perovskites are among the most promising perovskite compositions for application in a variety of optoelectronic devices due to their high performance, low cost, and bandgap-tuning capabilities. Instability pathways such as those driven by ionic migration, however, continue to hinder their further progress. Here, an operando variable-pitch synchrotron grazing-incidence wide-angle X-ray scattering technique is used to track the surface and bulk structural changes in mixed-halide mixed-cation perovskite solar cells under continuous load and illumination. By monitoring the evolution of the material structure, it is demonstrated that halide remixing along the electric field and illumination direction during operation hinders phase segregation and limits device instability. Correlating the evolution with directionality- and depth-dependent analyses, it is proposed that this halide remixing is induced by an electrostrictive effect acting along the substrate out-of-plane direction. However, this stabilizing effect is overwhelmed by competing halide demixing processes in devices exposed to humid air or with poorer starting performance. The findings shed new light on understanding halide de- and re-mixing competitions and their impact on device longevity. These operando techniques allow real-time tracking of the structural evolution in full optoelectronic devices and unveil otherwise inaccessible insights into rapid structural evolution under external stress conditions.


Funder: Taiwan Cambridge Scolarship

Funder: Winton Studentship

Funder: Lloyd's Register Foundation; Id:

Funder: Royal Academy of Engineering; Id:


diffraction, electrostriction, perovskites, photosegregation, photovoltaics

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Adv Mater

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Royal Society (UF150033)
European Research Council (756962)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (841386)
EPSRC (1948703)
Leverhulme Trust (RPG-2021-191)
EPSRC (via University of Surrey) (RB3671)
Engineering and Physical Sciences Research Council (EP/R023980/1)
EPSRC (EP/T02030X/1)
Engineering and Physical Sciences Research Council (EP/S030638/1)
Engineering and Physical Sciences Research Council (EP/V027131/1)
The authors acknowledge the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (HYPERION, grant agreement No. 756962), and the Engineering and Physical Sciences Research Council (EPSRC) (grant agreement No. EP/R023980/1). E.R. was par- tially supported by an EPSRC Departmental Graduate Studentship. K.G. appreciates support from the Polish Ministry of Science and Higher Education within the Mobilnosc Plus program (grant agreement No. 1603/MOB/V/2017/0). A.A. acknowledges the Royal Society for funding. Y.-H.C. acknowledges funding from a Taiwan Cambridge Scholarship. K.J. acknowledges funding from the Royal Society (RGFR1180002). Z.A.-G. acknowledges funding from a Winton Studentship, and ICON Studentship from the Lloyd’s Regi- ster Foundation. M.A. acknowledges funding from the Marie Skłodowska-Curie actions (grant agreement No. 841386) under the European Union’s Horizon 2020 research and innovation programme, and from the Leverhulme Early Career Fellowship (grant agreement No. ECF-2019-224) funded by the Leverhulme Trust and the Isaac Newton Trust. S.D.S. also acknowledges the Royal Society and Tata Group (UF150033). This work utilized beamline I07 at the Diamond Light Source (Proposal SI17223).