Unusual Pressure-Driven Phase Transformation and Band Renormalization in 2D vdW Hybrid Lead Halide Perovskites.,Advanced Materials

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Unusual Pressure-Driven Phase Transformation and Band Renormalization in 2D vdW Hybrid Lead Halide Perovskites.
Advanced Materials ( IF 27.4 ) Pub Date : 2020-01-28 , DOI: 10.1002/adma.201907364
Han Li ₁ , Ying Qin ₁ , Bohan Shan ₁ , Yuxia Shen ₁ , Fatih Ersan _{2,

3} , Emmanuel Soignard ₄ , Can Ataca ₃ , Sefaattin Tongay ₁

Affiliation

The application of high pressure allows control over the unit cell and interatomic spacing of materials without any need for new growth methods or processing while accessing their materials properties in situ. Under these extreme pressures, materials may assume new structural phases and reveal novel properties. Here, unusual phase transition and band renormalization effects in 2D van der Waals Ruddlesden-Popper hybrid lead halide perovskites, which have shown extraordinary optical properties and immense potential in light emission and conversion technologies, are reported. The results show that (CH3 (CH2 )3 NH3 )2 (CH3 NH3 )Pb2 Br7 (n = 2) layers undergo two distinct phase transitions related to PbBr6 octahedra, butylammonium (BA), and methylammonium (MA) molecule tilting motion that leads to rather unique/anomalous bandgap variation with pressure. In contrast, (CH3 (CH2 )3 NH3 )PbBr4 (n = 1) lacks MA molecules and possesses only one pressure-induced phase transition related to PbBr6 octahedra and BA tilting. In this range, the bandgap reduces monotonically, much similar to other inorganic semiconductors and display surprisingly large redshift from 3 to 2.4 eV. Together with theoretical calculations, this study offers unique insights into these pressure-induced changes and extends the understanding of these highly anisotropic layered soft organic perovskite materials under extreme conditions.

中文翻译：

二维vdW混合卤化钙钛矿中异常的压力驱动相变和能带重整化。

施加高压可控制材料的晶胞和原子间间距，而无需任何新的生长方法或加工，同时可就地获得其材料特性。在这些极端压力下，材料可能会呈现新的结构相并展现出新的特性。在此，报道了二维范德华·鲁德斯登-珀珀杂化卤化钙钛矿中不寻常的相变和能带重归一化效应，这些结果显示出非凡的光学性能以及在发光和转换技术中的巨大潜力。结果表明（CH3（CH2）3 NH3）2（CH3 NH3）Pb2 Br7（n = 2）层经历了与PbBr6八面体，丁基铵（BA）和甲基铵（MA）分子倾斜运动有关的两个不同的相变随压力产生的独特/异常带隙变化。相反，（CH3（CH2）3 NH3）PbBr4（n = 1）缺少MA分子，并且仅具有一个与PbBr6八面体和BA倾斜有关的压力诱导相变。在此范围内，带隙单调减小，与其他无机半导体非常相似，并且显示出令人惊讶的从3 eV到2.4 eV的大红移。连同理论计算，本研究对这些压力引起的变化提供了独特的见解，并扩展了在极端条件下对这些高度各向异性的层状柔软有机钙钛矿材料的理解。与其他无机半导体非常相似，并且显示出令人惊讶的3到2.4 eV的大红移。连同理论计算，本研究对这些压力引起的变化提供了独特的见解，并扩展了对在极端条件下这些高度各向异性的层状柔软有机钙钛矿材料的理解。与其他无机半导体非常相似，并且显示出令人惊讶的3到2.4 eV的大红移。连同理论计算，本研究对这些压力引起的变化提供了独特的见解，并扩展了在极端条件下对这些高度各向异性的层状柔软有机钙钛矿材料的理解。

更新日期：2020-03-24

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