Wenru Li1, Gang Tang2, Guangzu Zhang3, Hasnain Mehdi Jafri4, Jun Zhou1, Di Liu4, Yang Liu5, Jiesu Wang6, Kuijuan Jin6, Yongmin Hu7, Haoshuang Gu7, Zhao Wang7, Jiawang Hong8, Houbing Huang9, Long-Qing Chen5, Shenglin Jiang1, Qing Wang10. 1. School of Optical and Electronic Information, and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China. 2. School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China. 3. School of Optical and Electronic Information, and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China. zhanggz@hust.edu.cn hongjw@bit.edu.cn hbhuang@ustb.edu.cn wang@matse.psu.edu. 4. School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China. 5. Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA. 6. Institute of Physics, Chinese Academy of Sciences, Beijing, China. 7. Hubei Key Laboratory of Ferro- & Piezoelectric Materials and Devices, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, China. 8. School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China. zhanggz@hust.edu.cn hongjw@bit.edu.cn hbhuang@ustb.edu.cn wang@matse.psu.edu. 9. School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China. zhanggz@hust.edu.cn hongjw@bit.edu.cn hbhuang@ustb.edu.cn wang@matse.psu.edu. 10. Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA. zhanggz@hust.edu.cn hongjw@bit.edu.cn hbhuang@ustb.edu.cn wang@matse.psu.edu.
Abstract
Although ferroelectric materials exhibit large pyroelectric coefficients, their pyroelectric figures of merit (FOMs) are severely limited by their high dielectric constants because of the inverse relationship between FOMs and dielectric constant. Here, we report the molecular ferroelectric [Hdabco]ClO4 and [Hdabco]BF4 (dabco = diazabicyclo[2.2.2]octane) exhibiting improper ferroelectric behavior and pyroelectric FOMs outperforming the current ferroelectrics. Concurrently, the improper molecular ferroelectrics have pyroelectric coefficients that are more than one order of magnitude greater than the state-of-the-art pyroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 Our first-principles and thermodynamic calculations show that the strong coupling between the order parameters, i.e., the rotation angle of anions and polarization, is responsible for the colossal pyroelectric coefficient of the molecular ferroelectrics. Along with the facile preparation and self-poling features, the improper molecular ferroelectrics hold great promise for high-performance pyroelectric devices.
Although ferroelectric materials exhibit large pyroelectric coefficients, their pyroelectric figures of merit (FOMs) are severely limited by their high dielectric constants because of the inverse relationship between FOMs and dielectric constant. Here, we report the molecular pan class="Chemical">ferroelectric [Hdabco]ClO4 and [Hdabco]BF4 (dabco = diazabicyclo[2.2.2]octane) exhibiting improper ferroelectric behavior and pyroelectric FOMs outperforming the current ferroelectrics. Concurrently, the improper molecular ferroelectrics have pyroelectric coefficients that are more than one order of magnitude greater than the state-of-the-art pyroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 Our first-principles and thermodynamic calculations show that the strong coupling between the order parameters, i.e., the rotation angle of anions and polarization, is responsible for the colossal pyroelectric coefficient of the molecular ferroelectrics. Along with the facile preparation and self-poling features, the improper molecular ferroelectrics hold great promise for high-performance pyroelectric devices.