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Room temperature ferroelectricity of hybrid organic-inorganic perovskites with mixed iodine and bromine


Ferroelectricity has been reported in organic-inorganic perovskites, and it can enhance the power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) because ferroelectricity can facilitate charge carrier separation and charge transport through the perovskite layer. However, the existence of ferroelectricity in perovskites has been in hot debate, particularly at room temperature. Here, we report the ferroelectric polarization switching of MAPb(I1-xBrx)3 which showed a high dependence on its composition. The ferroelectric behavior of MAPbI3-50% PbBr2 is confirmed with domain switching by Piezoelectric Force Microscopy (PFM) imaging and bias-off “butterfly-like” amplitude loops and piezoresponse hysteresis loops at room temperature. The possible factors, such as film electrical property attributing to the enhanced room-temperature ferroelectricity in MAPb(I1-xBrx)3 films are clarified by using conductive atomic force microscopy (C-AFM). In addition, the charge separation and charge transport in the perovskite MAPb(I1-xBrx)3 films are further investigated by Kelvin probe force microscopy (KPFM). Finally, the possible influences of the polarization orientations, the trapping effects and ions migrations within the MAPb(I1-xBrx)3 films on the J-V characteristics of PSC devices are discussed in detail. It begins to discover the polarization switching under positive tip biased condition in the PSCs with 50% PbBr2, which could hinder the photovoltaic performance. These findings help better understanding on the electronic structure of hybrid organic-inorganic perovskites and provide guidance for the improvement of the PSC performance and other electronic applications of perovskites.

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Publication details

The article was received on 12 Nov 2017, accepted on 15 Apr 2018 and first published on 17 Apr 2018

Article type: Paper
DOI: 10.1039/C7TA09967C
Citation: J. Mater. Chem. A, 2018, Accepted Manuscript
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    Room temperature ferroelectricity of hybrid organic-inorganic perovskites with mixed iodine and bromine

    J. Xiao, J. Chang, B. Li, F. H. Isikgor, Z. Fan, D. Wang, Z. Lin, J. Ouyang, K. Zeng and J. Chen, J. Mater. Chem. A, 2018, Accepted Manuscript , DOI: 10.1039/C7TA09967C

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