Toward Fluorinated Spacers for MAPI-Derived Hybrid Perovskites: Synthesis, Characterization, and Phase Transitions of (FC2H4NH3)2PbCl4
Toward Fluorinated Spacers for MAPI-Derived Hybrid Perovskites: Synthesis, Characterization, and Phase Transitions of (FC2H4NH3)2PbCl4
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DOI：
10.1021/acs.chemmater.6b02151
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发表时间：
2016-09-27
影响因子：
8.6
通讯作者：
Lotsch, Bettina V.
中科院分区：
文献类型：
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作者：
Lermer, Claudia;Birkhold, Susanne T.;Lotsch, Bettina V.
混合型钙钛矿型甲基碘化铅(MAPI)固有的水分敏感性要求采用新的合成策略来提高防潮性，从而提高长期稳定性。在这里，我们结合了两种策略：(I)通过插入更大的A位阳离子作为间隔体，从3D杂化钙钛矿过渡到2D杂化钙钛矿，以及(Ii)使用氟化连接物来增强材料的疏水性-并鉴定了两种新的杂化钙钛矿型化合物，(FC2H4NH3)(2)PbCl4和(FC2H4NH3)PbBr3中心点DMF，携带2-氟乙基铵(FC2H4NH3)(+)作为一种有希望的有机阳离子合成抗潮杂化钙钛矿。(FC2H4NH3)(2)PbCl4具有二维结构，经单晶和粉末X射线衍射证实具有明显的长期稳定性。用热分析、变温粉末X-射线衍射法和H-1、C-13和Pb-207固体核磁共振谱研究了在87℃和107℃观察到的可逆相变，分别归因于无机氯化铅和有机亚晶格的变化，两者在固体核磁共振谱上都有明显的指纹。密度泛函理论计算表明，(FC2H4NH3)(2)PbCl4中观察到的无机亚晶格严重扭曲的根源可追溯到结构特征，包括形成氢键。利用光学吸收光谱和时间分辨光致发光光谱研究了(FC2H4NH3)(2)PbCl4的光学性质，探讨了有机亚晶格和无机亚晶格之间的相互作用。由于激发态与晶格扭曲的强烈耦合，激子具有宽广的光致发光光谱和特殊的吸收特性，这与激子自陷有关。
The intrinsic moisture sensitivity of the hybrid perovskite methylammonium lead iodide (MAPI) calls for new synthetic strategies to enhance moisture resistance and, thus, long-term stability. Here, we combine two strategies: (i) transitioning from 3D to 2D hybrid perovskites by inserting larger A-site cations as spacers and (ii) using fluorinated linkers to enhance the hydrophobicity of the material-and identify two new hybrid perovskite-type compounds, (FC2H4NH3)(2)PbCl4 and (FC2H4NH3)PbBr3 center dot DMF, carrying 2-fluoroethylammonium (FC2H4NH3)(+) as a promising organic cation for the synthesis of moisture-resistant hybrid perovskites. (FC2H4NH3)(2)PbCl4 features a two-dimensional structure and pronounced long-term stability as confirmed by single-crystal and powder X-ray diffraction. The observed reversible phase transitions at 87 and 107 C investigated with thermal analysis, temperature-dependent powder X-ray diffraction measurements, and H-1, C-13, and Pb-207 solid-state NMR spectroscopy can be assigned to changes in the inorganic lead chloride and organic sublattices, respectively, both having clearly observable fingerprints in the solid-state NMR spectra. DFT calculations trace the origin of the observed severe distortion of the inorganic sublattice in (FC2H4NH3)(2)PbCl4 back to structural features including the formation of hydrogen bonds. The optical properties of (FC2H4NH3)(2)PbCl4 were characterized by optical absorption spectroscopy and time-resolved photoluminescence measurements with a view toward the interaction between the organic and inorganic sublattices. The broad photoluminescence spectrum as well as specific absorption characteristics are assigned to exciton self-trapping due to a strong coupling of the excited states to lattice distortions.