Wei Chuanxin, Li Liang, Zheng Yingying, Wang Lizhi, Ma Jingyao, Xu Man, Lin Jinyi, Xie Linghai, Naumov Panče, Ding Xuehua, Feng Quanyou, Huang Wei
State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 211816, China.
Chem Soc Rev. 2024 Apr 22;53(8):3687-3713. doi: 10.1039/d3cs00116d.
The cornerstones of the advancement of flexible optoelectronics are the design, preparation, and utilization of novel materials with favorable mechanical and advanced optoelectronic properties. Molecular crystalline materials have emerged as a class of underexplored yet promising materials due to the reduced grain boundaries and defects anticipated to provide enhanced photoelectric characteristics. An inherent drawback that has precluded wider implementation of molecular crystals thus far, however, has been their brittleness, which renders them incapable of ensuring mechanical compliance required for even simple elastic or plastic deformation of the device. It is perplexing that despite a plethora of reports that have in the meantime become available underpinning the flexibility of molecular crystals, the "discovery" of elastically or plastically deformable crystals remains limited to cases of serendipitous and laborious trial-and-error approaches, a situation that calls for a systematic and thorough assessment of these properties and their correlation with the structure. This review provides a comprehensive and concise overview of the current understanding of the origins of crystal flexibility, the working mechanisms of deformations such as plastic and elastic bending behaviors, and insights into the examples of flexible molecular crystals, specifically concerning photoelectronic changes that occur in deformed crystals. We hope this summary will provide a reference for future experimental and computational efforts with flexible molecular crystals aimed towards improving their mechanical behavior and optoelectronic properties, ultimately intending to advance the flexible optoelectronic technology.
柔性光电子学发展的基石是设计、制备和利用具有良好机械性能和先进光电子特性的新型材料。分子晶体材料由于预期能减少晶界和缺陷以提供增强的光电特性，已成为一类尚未充分探索但很有前景的材料。然而，迄今为止，阻碍分子晶体更广泛应用的一个固有缺点是它们的脆性，这使得它们甚至无法确保器件进行简单弹性或塑性变形所需的机械顺应性。令人困惑的是，尽管与此同时有大量报告支持分子晶体的柔韧性，但可弹性或塑性变形晶体的“发现”仍然局限于偶然且费力的试错方法的案例，这种情况需要对这些特性及其与结构的相关性进行系统而全面的评估。本综述全面而简要地概述了目前对晶体柔韧性起源的理解、塑性和弹性弯曲行为等变形的工作机制，以及对柔性分子晶体实例的见解，特别是关于变形晶体中发生的光电变化。我们希望这一总结能为未来旨在改善其机械行为和光电子特性的柔性分子晶体的实验和计算工作提供参考，最终推动柔性光电子技术的发展。
