Li Lin-Sui, Tan Yu-Hui, Wei Wen-Juan, Gao Hong-Qiang, Tang Yun-Zhi, Han Xiao-Bo
Engineering Research Institute, Jiangxi University of Science and Technology, Ganzhou 341000, China.
Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan 430205, China.
ACS Appl Mater Interfaces. 2021 Jan 13;13(1):2044-2051. doi: 10.1021/acsami.0c19507. Epub 2020 Dec 21.
Low-dimensional hybrid organic-inorganic perovskites (HOIPs) possess more localized electronic states and narrower conduction and valence bands to promote self-trapping of excitons and stronger exciton emission; therefore, they are widely used as building blocks for various applications in the fields of optoelectronics, photovoltaics, light-emitting diodes, luminescence, fluorescence, and so forth. Despite the past decades of intensive study, the discovered low-dimensional chiral HOIPs are rare as of the 1D chiral HOIP single crystals reported in 2003, as well as the low-dimensional chiral HOIP ferroelectrics are particularly scarce since the first chiral two-dimensional (2D) and/or one-dimensional (1D) HOIP ferroelectrics reported. Herein, two new low-dimensional HOIPs with the same conformational formula [R-MPA]CdCl (R-MPA = ()-(-)-1-methyl-3-phenylpropylamine) were successfully synthetized by means of regulating the stoichiometric proportion of R-MPA and CdCl in two ways of 1:1 () and 2:1 (). By combining single-crystal X-ray diffraction, circular dichroism (CD) spectroscopy, differential scanning calorimetry, temperature-dependent dielectric constant, temperature-dependent second-harmonic generation (SHG) effect, polarization-dependent SHG response, and - hysteresis loop, we reveal that is a 1D nonchiral molecular ferroelectric and is the first zero-dimensional (0D) chiral ferroelectric with distinct CD signals; meanwhile, exhibits increased properties of high-, large dielectric constant, SHG isotropy, and ferroelectricity than that of . These results not only shed light on the high tunability of the low-dimensional HOIP ferroelectrics but also open up an avenue to explore multifunctional chiral ferroelectrics.
低维有机-无机杂化钙钛矿（HOIPs）具有更多的局域电子态以及更窄的导带和价带，以促进激子的自陷和更强的激子发射；因此，它们被广泛用作光电子学、光伏、发光二极管、发光、荧光等领域各种应用的构建块。尽管在过去几十年进行了深入研究，但截至2003年报道的一维手性HOIP单晶，已发现的低维手性HOIPs仍然很少，而且自首次报道手性二维（2D）和/或一维（1D）HOIP铁电体以来，低维手性HOIP铁电体尤其稀少。在此，通过以1:1（）和2:1（）两种方式调节R-MPA和CdCl的化学计量比，成功合成了两种具有相同构象式[R-MPA]CdCl（R-MPA =（）-（-）-1-甲基-3-苯基丙胺）的新型低维HOIPs。通过结合单晶X射线衍射、圆二色性（CD）光谱、差示扫描量热法、温度依赖性介电常数、温度依赖性二次谐波产生（SHG）效应、偏振依赖性SHG响应和-滞后回线，我们揭示了是一维非手性分子铁电体，并且是具有明显CD信号的首个零维（0D）手性铁电体；同时，与相比，表现出更高的、大介电常数、SHG各向同性和铁电性。这些结果不仅揭示了低维HOIP铁电体的高可调性，而且为探索多功能手性铁电体开辟了一条途径。
