Abstract

Two-dimensional (2D) metal halide perovskites feature several specific advantages over others 2D materials, such as facile wet chemical synthesis and layers exfoliation, high composition combination especially the choice of organic cations as well as 2D phase, excellent confinement for exciton. In this paper, we present a fundamental study of diaminonaphthalene lead iodide (DANPI) perovskite, a Dion–Jacobson 2D perovskite based on divalent cation organic spacer 1,5-diaminonaphthalene. We report its material synthesis, optical and structural characterization as well as DFT calculations. Hydro-iodic acid-based wet chemistry was used to prepare DANPI crystals and, by cast-capping, thin films as well. Both DANPI materials show a dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm. This peak coincides with the absorption edge of the material at 510 nm (2.43 eV) which suggests an exciton-related recombination process. According to single-crystal X-ray diffraction measurements the crystal structure could be either monoclinic P21/c or tetragonal P4212. DFT calculations including spin–orbit coupling show that the DANPI band gap is direct, with a valence band of s-symmetry and a conduction band of p-symmetry.

Graphical Abstract

• A dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm.

• The crystal structure could be either monoclinic P21/c or tetragonal P4212.

• The DANPI band gap is direct, at 2.43 eV, with a valence band of s-symmetry and a conduction band of p-symmetry.

• Suggested Dexter electron exchange process for Wannier excitons to organic Frenkel excitons.

中文翻译：

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Dion-Jacobson 二维钙钛矿的合成与表征

摘要

二维（2D）金属卤化物钙钛矿与其他2D材料相比具有一些特定的优势，例如容易的湿化学合成和层剥离、高成分组合尤其是有机阳离子和2D相的选择、对激子的优异限制。在本文中，我们提出了二氨基萘碘化铅（DANPI）钙钛矿的基础研究，这是一种基于二价阳离子有机间隔基1,5-二氨基萘的Dion-Jacobson 2D钙钛矿。我们报告了其材料合成、光学和结构表征以及 DFT 计算。基于氢碘酸的湿化学法用于制备 DANPI 晶体，并通过铸封法制备薄膜。两种 DANPI 材料均显示出约 519 nm 的主发射峰，半峰全宽小至 14 nm。该峰与材料在 510 nm (2.43 eV) 处的吸收边一致，这表明存在与激子相关的复合过程。根据单晶X射线衍射测量，晶体结构可以是单斜晶系P21/c或四方晶系P4212。包括自旋轨道耦合在内的 DFT 计算表明，DANPI 带隙是直接的，具有 s 对称的价带和 p 对称的导带。

图形概要

• 主发射峰位于约 519 nm 处，半峰全宽小至 14 nm。

• 晶体结构可以是单斜晶系 P21/c 或四方晶系 P4212。

• DANPI 带隙是直接带隙，为 2.43 eV，具有 s 对称的价带和 p 对称的导带。

• 建议的万尼尔激子到有机弗伦克尔激子的德克斯特电子交换过程。