Hybrid organic–inorganic perovskites (HOIPs) have garnered widespread interest, yet stability remains a critical issue that limits their further application. Compared to their three-dimensional (3D) counterparts, two-dimensional (2D)-HOIPs exhibit improved stability. 2D-HOIPs are also appealing because their structural and optical properties can be tuned according to the choice of organic ligand, with monovalent or divalent ligands forming Ruddlesden–Popper (RP) or Dion–Jacobson (DJ)-type 2D perovskites, respectively. Unlike RP-type 2D perovskites, DJ-type 2D perovskites do not contain a van der Waals gap between the 2D layers, leading to improved stability. However, bifunctional organic ligands currently used to develop DJ-type 2D perovskites are limited to commercially available aliphatic and single-ring aromatic ammonium cations. Large conjugated organic ligands are in demand for their semiconducting properties and their potential to improve materials stability further. In this manuscript, we report the design and synthesis of a new set of larger conjugated diamine ligands and their incorporation into DJ-type 2D perovskites. Compared with analogous RP-type 2D perovskites, DJ 2D perovskites reported here show blue-shifted, narrower emissions and significantly improved stability. By changing the structure of rings (benzene vs thiophene) and substituents, we develop structure–property relationships, finding that fluorine substitution enhances crystallinity. Single-crystal structure analysis and density functional theory calculations indicate that these changes are due to strong electrostatic interactions between the organic templates and inorganic layers as well as the rigid backbone and strong π–π interaction between the organic ligands themselves. These results illustrate that targeted engineering of the diamine ligands can enhance the stability of DJ-type 2D perovskites.

中文翻译：

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用于稳定 Dion-Jacobson 型二维钙钛矿的刚性共轭二胺模板

杂化有机-无机钙钛矿（HOIPs）引起了广泛的兴趣，但稳定性仍然是限制其进一步应用的关键问题。与其三维 (3D) 对应物相比，二维 (2D)-HOIP 表现出更高的稳定性。2D-HOIPs 也很有吸引力，因为它们的结构和光学特性可以根据有机配体的选择进行调整，单价或二价配体分别形成 Ruddlesden-Popper (RP) 或 Dion-Jacobson (DJ) 型 2D 钙钛矿。与 RP 型 2D 钙钛矿不同，DJ 型 2D 钙钛矿在 2D 层之间不包含范德华间隙，从而提高了稳定性。然而，目前用于开发 DJ 型 2D 钙钛矿的双功能有机配体仅限于市售的脂肪族和单环芳香族铵阳离子。大的共轭有机配体因其半导体特性和进一步提高材料稳定性的潜力而受到需求。在这份手稿中，我们报告了一组新的更大的共轭二胺配体的设计和合成，以及它们与 DJ 型二维钙钛矿的结合。与类似的 RP 型 2D 钙钛矿相比，此处报道的 DJ 2D 钙钛矿显示出蓝移、更窄的发射和显着提高的稳定性。通过改变环的结构（苯与噻吩）和取代基，我们建立了结构-性能关系，发现氟取代增强了结晶度。单晶结构分析和密度泛函理论计算表明，这些变化是由于有机模板和无机层之间的强静电相互作用以及刚性骨架和有机配体本身之间的强 π-π 相互作用。这些结果表明，二胺配体的靶向工程可以增强 DJ 型 2D 钙钛矿的稳定性。