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Impact of Rubidium and Cesium Cations on the Moisture Stability of Multiple-Cation Mixed-Halide Perovskites
journal contribution
posted on 2017-08-30, 00:00 authored by Yinghong Hu, Meltem F. Aygüler, Michiel L. Petrus, Thomas Bein, Pablo DocampoRubidium and cesium cations have
been recently identified as enhancers
for perovskite solar cell performance. However, the impact of these
inorganic cations on the stability of the (FA0.83MA0.17)Pb(I0.83Br0.17)3 perovskite
crystal lattice has not been fully understood yet. Here, we show via
in situ X-ray diffraction and energy-dispersive X-ray spectrometry
measurements that the unsuitably small ionic radius of Rb+ can lead to several nonphotoactive side-products. During the perovskite
film synthesis, RbPb(I1–xBrx)3 is formed, while exposure to
humid air leads to the rapid formation of another hitherto unreported
side phase (RbPb2I4Br). The formation of the
Rb-rich side phases not only results in a loss of light absorption
but also extracts bromide ions from the photoactive perovskite phase,
thereby reducing its band gap. In comparison, the moisture-assisted
formation of a CsPb2I4Br phase upon Cs-addition
occurs on a significantly longer time scale than its Rb analog. While
the incorporation of Cs+ remains attractive for high-performance
solar cells, the severe moisture-sensitivity of Rb-containing mixed-halide
perovskites may create additional engineering challenges.
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extracts bromide ionsphotoactive perovskite phaseband gapimpactside phasetime scalecell performanceMoisture Stability4 Br phase4 BrX-ray diffractionRb analogMultiple-Cation Mixed-Halide Perovskites Rubidiummoisture-assisted formationRbPb 2CsPb 2cesium cationsMA3 perovskite crystal latticeFAlight absorption0.83nonphotoactive side-productsRb-rich side phases0.17Rb-containing mixed-halide perovskitesCesium Cationsengineering challengesperovskite film synthesisenergy-dispersive X-ray spectrometry measurements
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