Recently, under the sponsorship of the launch and cultivation fund of “Ten Scientific and Technological Issues of Southeast University”, the International Molecular Ferroelectric Science and Application Research Instituteof Southeast University and the “Molecular Ferroelectric Science and Application” Key Laboratory of Jiangsu Province proposed the rational fluorine-modified design strategy, the molecular ferroelectric. The research team is composed of undergraduates from the College of Chemistry and Chemical Engineering as the main team members, and is independently guided by the young professor You Yumeng.
The team's research result was included by “Advanced Materials”, an international top journal in the field of material with the title of “Fluorinated 2D lead iodide perovskite ferroelectrics”, the undergraduate students Sha Taiting and Xiong Yu’an from the School of Chemistry and Chemical Engineering of Southeast University as the co-first authors. In addition, other authors include undergraduate students Miao Shurong, Jing Zhengyin and Feng Zijie. This also represents one of their research achievements obtained in their participation in the “Challenge Cup” college students' extracurricular academic works. Besides, this achievement was also attributed to Pan Qiang, the special prize winner of the preceding “Challenge Cup”, Dr. Song Xianjiang, Dr. Chen Xiaogang and the graduate student Yao Jie for their joint efforts. The only correspondent of this paper is You Yumeng.
By using thefluorine-modified design strategy, the research team obtained a new two-dimensional fluoro-layered hybrid perovskite material (4,4-difluorocyclohexylammonium) 2PbI4 by improving the non-ferroelectric lead iodide perovskite; and its ferroelectricity has been also verified. Meanwhile, its strong UV-visible absorption and direct band gap of 2.38eV has also guaranteed that it can directly observe the polarization-induced ferroelectric photovoltaic effect. More importantly, its two-dimensional structure is also expected to improve the stability of perovskite photovoltaic materials, which has provided a new thought of solving the service life of perovskite photovoltaic materials. The two-dimensional fluorinated lead iodide with proven ferroelectricity as designed and synthesized by the research team is not only deemed as a new hybrid perovskite material highlighting solar photovoltaic application prospects, but also has provided an ideal research platform for studying the role of ferroelectricity and ferroelectric photovoltaic effects in the lead halide perovskite solar cells and other optoelectronic applications.