Molecular ferroelectrics with low power consumption offer environmental and economic advantages over conventional ferroelectrics and could lead to next-generation microelectronic devices. To this end, it is of great importance to understand the conditions under which molecules can be engineered to form large-area, highly oriented thin films, as their electrical properties depend on orientation. In the research field of molecular ferroelectrics, homochiral multifunctional organic molecules are often used to induce the self-assembly of molecules through non-covalent interactions to form polar crystal packings and consequently ferroelectric properties. Here, molecular ferroelectric thin films based on the natural Cinchona alkaloid, cinchoninium cation and chlorocobaltate(II) anion were prepared by a dip-coating technique without post-thermal treatment and assisted stabilization process. The deposition parameters (relative humidity, temperature, concentration and withdrawal speed) were modified to produce either completely dense or fully patterned films with randomly distributed holes on the surfaces. While non-covalent interactions are the main factor in determining the structure of cinchoninium-trichloro-cobalt(II) thin films, relative humidity is a key parameter in the simultaneous self-organization happening at the mesoscale, acting as a dewetting agent. Dense cinchoninium-trichloro-cobalt(II) films exhibit a stable ferroelectric switching at a low operating voltage, and patterned films were tested as resistive methanol sensors.

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基于天然生物碱的大规模分子铁电薄膜的湿度调制表面图案


与传统铁电体相比，低功耗的分子铁电体具有环境和经济优势，并可能导致下一代微电子器件。为此，了解分子可以被设计成大面积、高度取向的薄膜的条件非常重要，因为它们的电学特性取决于取向。在分子铁电体研究领域，同手性多功能有机分子经常被用来通过非共价相互作用诱导分子自组装，形成极性晶体堆积，从而产生铁电性质。在这里，基于天然金鸡纳生物碱、金鸡鎓阳离子和氯钴酸盐 （II） 阴离子的分子铁电薄膜是通过浸涂技术制备的，无需后热处理和辅助稳定过程。修改沉积参数（相对湿度、温度、浓度和提取速度）以产生完全致密或完全图案化的薄膜，表面有随机分布的孔。虽然非共价相互作用是决定金鸡鎓-三氯-钴 （II） 薄膜结构的主要因素，但相对湿度是在中尺度上同时发生的自组织的关键参数，充当去湿剂。致密的金鸡鎏-三氯-钴 （II） 薄膜在低工作电压下表现出稳定的铁电开关，并且图案薄膜作为电阻甲醇传感器进行了测试。