Phase Transition of Low-dimensional Lead Halide Perovskite-type Compounds

低维卤化铅钙钛矿型化合物的相变

• 批准号: 10640297
• 负责人: MATSUISHI Kiyoto
• 金额: $ 1.86万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640297/
• 关键词: Low-dimensional Semiconductors; Perovskite Compounds; Phase Transition; Raman Scattering; Phonon; Pressure Effects; Optical Properties; Luminescence; ペロブスカイト化合物; 熱分析

Single crystals of leadhalide perovskite-type compounds (3D : CHィイD23ィエD2NHィイD23ィエD2Pb(ClィイD21-XィエD2BrィイD2XィエD2)ィイD23ィエD2, 2D : (CィイD2mィエD2HィイD22m+1ィエD2NHィイD23ィエD2)ィイD22ィエD2(CHィイD23ィエD2NHィイD23ィエD2)ィイD2n-1ィエD2PbィイD2nィエD2XィイD23n+1ィエD2 (m=4, 6, 8, n=1, 2, X : Cl, I), 1D : CィイD25ィエD2HィイD210ィエD2NHィイD22ィエD2PbXィイD23ィエD2 (X : I, Br), 0D : (CHィイD23ィエD2NHィイD23ィエD2)ィイD24ィエD2PbIィイD26ィエD22HィイD22ィエD2O), in which the connectivity of [PbXィイD26ィエD2]ィイD14-ィエD1 octahedra (X : Cl, I, Br) was varied from 0 to 3 dimension, were prepared by a solution method. The structural dimension dependence of the phase transition was studied systematically (1) through vibrational properties of intramolecular modes, phonon modes, and quasi-elastic modes by Raman scattering and IR measurements, (2) through electronic properties by optical absorption, photoconductivity and photoluminescence measurements, (3) through thermal properties by differential scanning calorimetry measurements. We have found that the successive stru … More ctural phase transitions are governed, in common in these compounds except for the 0D sample, by the rotational and/or orientational ordering of the organic molecules, which induces a change in the electronic state of the [PbXィイD26ィエD2]ィイD14-ィエD1 sublattice. The results suggest that the structural distortion of the [PbXィイD26ィエD2]ィイD14-ィエD1 octahedra sublattice due to the rotational and orientational order/disorder transformation of the organic molecules plays an important role on the change in the electronic states at the structural phase transitions. We have clarified the dynamics and the kinetics of the rotational/orientational transformation of the organic molecules by the analyses of the linewidths of intramolecular modes and quasi-elastic modes. For the 1D sample, we discovered for the first time the successive phase transitions at 248, 253, and 284.5 K and the pressure-induced phase transition at 0.4 GPa due to the rotational/orientational ordering of CィイD25ィエD2HィイD210ィエD2NHィイD22ィエD2. For the 2D sample, we measured the optical absorption and photoluminescence spectra up to 25 GPa, and found the disappearance of the excitonic band around 10 GPa, indicating an electronic transition from a direct to an indirect band structure. Less

卤化铅钙钛矿型化合物单晶（3D：CHィイD23ィエD2NHィイD23ィエD2Pb（ClィイD21-XィエD2BrィイD2XィエD2）ィイD23ィエD2，2D： (CィイD2mィエD2HィイD22m+1ィエD2NHィイD23ィエD2)ィイD22ィエD2(CHィイD2 3ィエD2NHィイD23ィエD2)ィイD2n-1ィエD2PbィイD2nィエD2XィイD23n+1ィエD2 (m=4, 6, 8, n=1, 2, X : Cl, I), 1D : CィイD25ィエD2HィイD210ィエD2NHィイD22ィエD2PbXィイD23ィエD2 (X : I, Br), 0D : (CHィイD23ィエD2NHィイD23ィエD2)ィイD24ィエD2PbIィイD26ィエD22HィイD22ィエD2O)，其中连通性[PbXィイD26ィエD2]ィイD14-ィエD1八面体（X：Cl、I、Br）从0维到3维变化，通过溶液法制备。系统地研究了相变的结构尺寸依赖性：(1) 通过拉曼散射和红外测量，通过分子内模式、声子模式和准弹性模式的振动特性，(2) 通过光吸收、光电导和光致发光测量，通过电子特性，(3) 通过差示扫描量热法测量，通过热特性。我们发现，除了 0D 样品外，这些化合物中的连续结构相变普遍受到有机分子的旋转和/或取向排序的控制，这会引起 [PbXィイD26ィエD2]ィイD14-ィエD1 子晶格的电子态发生变化。结果表明，由于有机分子的旋转和取向有序/无序转变而导致的[PbXィイD26ィエD2]ィイD14-ィエD1八面体亚晶格的结构畸变对结构相变时电子态的变化起着重要作用。通过分析分子内模式和准弹性模式的线宽，阐明了有机分子旋转/取向转变的动力学和动力学。对于一维样品，我们首次发现由于 CィイD25ィエD2HィイD210ィエD2NHィイD22ィD2 的旋转/取向排序而在 248、253 和 284.5 K 处发生连续相变，以及在 0.4 GPa 处压力引起的相变。对于二维样品，我们测量了高达 25 GPa 的光吸收和光致发光光谱，发现激子带在 10 GPa 左右消失，表明电子从直接能带结构转变为间接能带结构。较少的

项目成果

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