Issue 39, 2023

Control of electronic polarization via charge ordering and electron transfer: electronic ferroelectrics and electronic pyroelectrics

Abstract

Ferroelectric, pyroelectric, and piezoelectric compounds whose electric polarization properties can be controlled by external stimuli such as electric field, temperature, and pressure have various applications, including ferroelectric memory materials, sensors, and thermal energy-conversion devices. Numerous polarization switching compounds, particularly molecular ferroelectrics and pyroelectrics, have been developed. In these materials, the polarization switching usually proceeds via ion displacement and reorientation of polar molecules, which are responsible for the change in ionic polarization and orientational polarization, respectively. Recently, the development of electronic ferroelectrics, in which the mechanism of polarization change is charge ordering and electron transfer, has attracted great attention. In this article, representative examples of electronic ferroelectrics are summarized, including (TMTTF)2X (TMTTF = tetramethyl-tetrathiafulvalene, X = anion), α-(BEDT-TTF)2I3 (BEDT-TTF = bis(ethylenedithio)-tetrathiafulvalene), TTF–CA (TTF = tetrathiafulvalene, CA = p-chloranil), and [(n-C3H7)4N][FeIIIFeII(dto)3] (dto = 1,2-dithiooxalate = C2O2S2). Furthermore, polarization switching materials using directional electron transfer in nonferroelectrics, the so-called electronic pyroelectrics, such as [(Cr(SS-cth))(Co(RR-cth))(μ-dhbq)](PF6)3 (dhbq = deprotonated 2,5-dihydroxy-1,4-benzoquinone, cth = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraaza-cyclotetradecane), are introduced. Future prospects are also discussed, particularly the development of new properties in polarization switching through the manipulation of electronic polarization in electronic ferroelectrics and electronic pyroelectrics by taking advantage of the inherent properties of electrons.

Graphical abstract: Control of electronic polarization via charge ordering and electron transfer: electronic ferroelectrics and electronic pyroelectrics

Article information

Article type
Perspective
Submitted
05 7 2023
Accepted
31 8 2023
First published
08 9 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 10631-10643

Control of electronic polarization via charge ordering and electron transfer: electronic ferroelectrics and electronic pyroelectrics

S. Su, S. Wu, S. Kanegawa, K. Yamamoto and O. Sato, Chem. Sci., 2023, 14, 10631 DOI: 10.1039/D3SC03432A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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