Moisture-Induced Non-Equilibrium Phase Segregation in Triple Cation Mixed Halide Perovskite Monitored by In Situ Characterization Techniques and Solid-State NMR

Energy & Environmental Materials

article

Mohammad Ali Akhavan Kazemi¹  Nicolas Folastre¹  Parth Raval²  Michel Sliwa³  Jean Marie Vianney Nsanzimana¹  Sema Golonu¹  Arnaud Demortiere¹  Jean Rousset⁴  Olivier Lafon²  Laurent Delevoye²  G. N. Manjunatha Reddy²  Frédéric Sauvage¹ 

[1] Laboratoire de Réactivité et Chimie des Solides ,(LRCS), UMR CNRS 7314 – Institut de Chimie de Picardie FR 3085, Université de Picardie Jules Verne;CNRS, Centrale Lille, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, Université de Lille, Université d'Artois;UMR 8516 – LASIRE – Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, CNRS, Université de Lille;EDF R&D, EDF Lab

关键词: liquid-cell transmission electron microscopy;    moisture degradation;    perovskite stability;    phase segregation;    solid-state NMR;   

DOI  :  10.1002/eem2.12335

来源: Wiley

【 摘 要 】

Environmental stability is a major bottleneck of perovskite solar cells. Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber. They mostly rely on ex situ experiments and on completely degraded samples, which restrict the assessment on initial and final stage. By combining in situ X-ray diffraction under controlled 85% relative humidity, and live observations of the water-induced degradation using liquid-cell transmission electron microscopy, we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-the-art mixed cation/anion (Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 (CsMAFA) into PbI2 through a dissolution/recrystallization mechanism and, on the other hand, to a non-equilibrium phase segregation leading to CsPb2Br5 and a Cesium-poor/iodide-rich Cs0.05-x(MA0.17FA0.83)0.95Pb(Br0.17−2yI0.83+2y)3 perovskite. This degradation mechanism is corroborated at atomic-scale resolution through solid-state 1H and 133Cs NMR analysis. Exposure to moisture leads to a film containing important heterogeneities in terms of morphology, photoluminescence intensities, and lifetimes. Our results provide new insights and consensus that complex perovskite compositions, though very performant as champion devices, are comparatively metastable, a trait that limits the chances to achieve long-term stability.

【 授权许可】

Unknown