Shi Pingping, a young teacher of Southeast University, reported the first case of fluorinated aromatic two-dimensional perovskite ferroelectrics

Recently, with the support of the "top ten scientific and technological issues of Southeast University" launch cultivation fund, Shi Pingping, a young teacher, worked together with the International Academy of molecular ferroelectric science and application of Southeast University and the key laboratory team of "molecular ferroelectric science and application" of Jiangsu Province to make important progress in the field of molecular ferroelectric research, The design and synthesis of two-dimensional organic-inorganic hybrid perovskite ferroelectrics with fluorinated aromatic groups are reported for the first time Relevant achievements were published in Journal of the American Chemical Society (DOI: 10.1021 / JACS 9b10048) under the title of "two dimensional organic Perovskite Ferroelectric semiconductor with the fluorinated territorial spacers" Compared with the traditional three-dimensional perovskite structure, the two-dimensional organic-inorganic hybrid perovskite system has more excellent stability and structural diversity, which provides a rich material platform for the design and control of related functions and device applications The research of this kind of materials is mainly concentrated in the fields of ferroelectricity, solar energy, light-emitting diodes, photodetectors and other high-tech fields Among them, two-dimensional organic-inorganic hybrid perovskite ferroelectrics have attracted special attention due to their considerable development potential in the application of multifunctional optoelectronic devices One of the biggest challenges is how to design and modulate ferroelectricity successfully by introducing polar structure into two-dimensional organic-inorganic hybrid perovskite system The similarity between fluorine and hydrogen in the van der Waals radius and other structural parameters can maintain the original stacking structure and crystal symmetry to the greatest extent, while the introduction of the most electronegative fluorine atom brings strong polarity and larger molecular dipole moment, which can help to enhance the crystal cell polarization Based on this, the team has successfully designed and synthesized the first two-dimensional organic-inorganic hybrid Perovskite Ferroelectric [2-fluorobenzylammonium] 2pbcl4 with fluoro aromatic group by using the "fluorination effect" modification strategy to obtain 2-fluorobenzylamine cation Its phase transition temperature is up to 448k, and it has outstanding ferroelectric properties and semiconductor characteristics This work provides a reliable way to expand the diversity of two-dimensional organic-inorganic hybrid Perovskite Ferroelectric system and improve the performance and stability of perovskite devices by using more complex conjugated aromatic cations, which will stimulate more relevant research The first author of this paper is Shi Pingping, a young teacher in the school of chemistry and chemical engineering of Southeast University.