Improper molecular ferroelectrics with simultaneous ultrahigh pyroelectricity and figures of merit

Wenru Li; Gang Tang; Guangzu Zhang; Hasnain Mehdi Jafri; Jun Zhou; Di Liu; Yang Liu; Jiesu Wang; Kuijuan Jin; Yongmin Hu; Haoshuang Gu; Zhao Wang; Jiawang Hong; Houbing Huang; Long-Qing Chen; Shenglin Jiang; Qing Wang

doi:10.1126/sciadv.abe3068

Improper molecular ferroelectrics with simultaneous ultrahigh pyroelectricity and figures of merit

Sci Adv. 2021 Jan 29;7(5):eabe3068. doi: 10.1126/sciadv.abe3068. Print 2021 Jan.

Authors

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

Affiliations

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(Mg_1/3Nb_2/3)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.

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