Quinuclidinium salt ferroelectric thin-film with duodecuple-rotational polarization-directions

Abstract

Ferroelectric thin-films are highly desirable for their applications on energy conversion, data storage and so on. Molecular ferroelectrics had been expected to be a better candidate compared to conventional ferroelectric ceramics, due to its simple and low-cost film-processability. However, most molecular ferroelectrics are mono-polar-axial, and the polar axes of the entire thin-film must be well oriented to a specific direction to realize the macroscopic ferroelectricity. To align the polar axes, an orientation-controlled single-crystalline thin-film growth method must be employed, which is complicated, high-cost and is extremely substrate-dependent. In this work, we discover a new molecular ferroelectric of quinuclidinium periodate, which possesses six-fold rotational polar axes. The multi-axes nature allows the thin-film of quinuclidinium periodate to be simply prepared on various substrates including flexible polymer, transparent glasses and amorphous metal plates, without considering the crystallinity and crystal orientation. With those benefits and excellent ferroelectric properties, quinuclidinium periodate shows great potential in applications like wearable devices, flexible materials, bio-machines and so on.

Piezoelectric Energy Harvesting Based on Multiaxial Ferroelectrics by Precise Molecular Design

“…Considering the application as polycrystalline ferroelectric materials or thin films, molecular-based multiaxial ferroelectrics are highly desirable because of their mechanical flexibility, structural tunability, environmentally friendly synthesis, and easy processing into thin films, and have great potential as next-generation flexible devices. [25][26][27] Studies on molecular ferroelectrics have been greatly developed in the past decade by the emergence of numerous excellent ferroelectrics, especially those with multiple polar axes and luminescence, as well as high spontaneous polarization and large piezoelectrics. [28][29][30][31] However, to date multiaxial molecular ferroelectrics have been greatly limited to very few plastic crystals composed of spherical ions.…”

Plastic/Ferroelectric Crystals with Easily Switchable Polarization: Low-Voltage Operation, Unprecedentedly High Pyroelectric Performance, and Large Piezoelectric Effect in Polycrystalline Forms

“…The perrhenate and periodate anions adopt nonpolar tetrahedral structures. These crystals exhibit ferroelectricity in the polycrystalline forms, due to the reorientation of the polar [AH] + cations, which is reminiscent of ferroelectric crystals composed of similarly structured molecules such as quinuclidinium perrhenate ( 3 ) and quinuclidinium periodate ( 4 ) . While the ferroelectric performance of 2 was limited to below room temperature, the low E c values of 1 in the room-temperature phase enabled low-voltage switching (<5 V) of the ferroelectric polarization.…”

Order–disorder transition of a rigid cage cation embedded in a cubic perovskite

“…Another familiar spheroidal cation quinuclidinium (Q + , Table 1 ) has not been reported to be contained in a framework. Several binary salts of Q + have been studied 25 , 26 to reveal the existence of an intermediate-temperature (IT) phase, where Q + rotates around its three-fold axis like an ellipsoid. Taking a lesson from the downsides of TMA + and Q + , a polycyclic ammonium with 5–6 carbons, i.e., a small molecular cage, would better resemble a rigid sphere.…”