东南大学张闻团队报道了低共熔温度大可熔窗口二维金属卤化物钙钛矿的合理设计。相关研究成果于2024年3月22日发表在《美国化学会杂志》。

金属卤化物钙钛矿（MHPs）由于其独特的光学和电子性能，以及优异的加工性能而引起了人们的极大关注。然而，这些材料的热特性往往被忽视，可以用来满足不同的应用场景。

该文中，研究人员展示了采用通过N-甲基化和I-取代修饰柔性烷基铵的策略，来降低层状2D MHPs的一致熔融温度（Tm）的功效。结构-性能分析表明，N-甲基化和I-取代在减少有机成分和无机成分之间的氢键相互作用、降低阳离子的旋转对称数，和限制阳离子的残余运动方面发挥着关键作用。额外的I··I相互作用增强了分子间的相互作用，并导致熔融稳定性的提高，如更高的粘度所证明的。

该研究中讨论的2D MHPs具有低Tm和宽的可熔融加工窗口，例如，（DMIPA）₂PbI₄表现出98°C的低Tm和约145°C的大的可熔融处理窗口。当应用于溴取代的2D MHPs时，该策略的有效性得到了进一步验证。降低Tm和提高MHPs的熔融稳定性在各种应用中都有很大的前景，包括玻璃形成、用于光电检测的高质量薄膜的制备和柔性器件的制造。

附：英文原文

Title: Rational Design of 2D Metal Halide Perovskites with Low Congruent Melting Temperature and Large Melt-Processable Window

Author: Wei Wang, Cheng-Dong Liu, Chang-Chun Fan, Xiao-Bin Fu, Chang-Qing Jing, Ming-Liang Jin, Yu-Meng You, Wen Zhang

Issue&Volume: March 22, 2024

Abstract: Metal halide perovskites (MHPs) have garnered significant attention due to their distinctive optical and electronic properties, coupled with excellent processability. However, the thermal characteristics of these materials are often overlooked, which can be harnessed to cater to diverse application scenarios. We showcase the efficacy of lowering the congruent melting temperature (Tm) of layered 2D MHPs by employing a strategy that involves the modification of flexible alkylammonium through N-methylation and I-substitution. Structural–property analysis reveals that the N-methylation and I-substitution play pivotal roles in reducing hydrogen bond interactions between the organic components and inorganic parts, lowering the rotational symmetry number of the cation and restricting the residual motion of the cations. Additional I···I interactions enhance intermolecular interactions and lead to improved molten stability, as evidenced by a higher viscosity. The 2D MHPs discussed in this study exhibit low Tm and wide melt-processable windows, e.g., (DMIPA)2PbI4 showcasing a low Tm of 98 °C and large melt-processable window of 145 °C. The efficacy of the strategy was further validated when applied to bromine-substituted 2D MHPs. Lowering the Tm and enhancing the molten stability of the MHPs hold great promise for various applications, including glass formation, preparation of high-quality films for photodetection, and fabrication of flexible devices.

DOI: 10.1021/jacs.4c00768

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c00768