Lookup NU author(s): Dr Pablo Docampo
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
© 2017 American Chemical Society. Rubidium 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.
Author(s): Hu Y, Ayguler MF, Petrus ML, Bein T, Docampo P
Publication type: Article
Publication status: Published
Journal: ACS Energy Letters
Print publication date: 13/10/2017
Online publication date: 30/08/2017
Acceptance date: 30/08/2017
Date deposited: 18/12/2017
ISSN (electronic): 2380-8195
Publisher: American Chemical Society
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