Abstract

In this article we prepared a novel layered hybrid halide perovskite (Ac,MA)PbI₄ containing acetamidinium (Ac⁺) and methylammonium (MA⁺) cations in form of single crystals and thin films. This compound exhibits a rare for (100)‑oriented perovskites crystal structure with an alternating cations in the interlayer space (ACI) where rotating distortions of adjacent inorganic layers results in alternating cuboctahedral voids of different sizes: the larger ones are occupied by Ac⁺ and the smaller ones by MA⁺. The crystal structure is also characterized by an unusually short distance (4.23 Å) between axial iodine atoms of adjacent layers, which is less than the sum of corresponding Van der Waals radii. In addition, we proposed an easy route for the preparation of single-phase smooth and homogenous (Ac,MA)PbI₄ thin films and studied their optical properties by means of absorption spectroscopy and photoluminescence spectroscopy. The material has an optical bandgap about 2.22 eV which is significantly smaller than typical (100)‑oriented layered iodide perovskites and demonstrates a relatively large Stokes shift of photoluminescence with a maximum at 590 nm (2.10 eV).

中文翻译：

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乙脒-甲基铵基层状杂化卤化物钙钛矿 [CH3C(NH2)2][CH3NH3]PbI4：合成、结构和光学性质

摘要

在本文中，我们制备了一种新型层状杂化卤化物钙钛矿 (Ac,MA)PbI ₄ ，其含有单晶和薄膜形式的乙脒 (Ac ⁺ ) 和甲基铵 (MA ^{+ ) 阳离子。}该化合物表现出罕见的 (100) 取向钙钛矿晶体结构，在层间空间 (ACI) 中具有交替的阳离子，其中相邻无机层的旋转扭曲导致不同尺寸的交替立方八面体空隙：较大的空隙被 Ac ⁺和较小的 MA ⁺. 晶体结构的特征还在于相邻层的轴向碘原子之间的距离异常短（4.23 Å），小于相应范德华半径的总和。此外，我们提出了一种制备单相光滑均质(Ac,MA)PbI ₄薄膜的简单途径，并通过吸收光谱和光致发光光谱研究了它们的光学性质。该材料的光学带隙约为 2.22 eV，明显小于典型的 (100) 取向层状碘化物钙钛矿，并表现出相对较大的光致发光斯托克斯位移，最大值为 590 nm (2.10 eV)。