Large piezoelectric response in a Jahn-Teller distorted molecular metal halide

Abstract

Piezoelectric materials convert between mechanical and electrical energy and are a basis for self-powered electronics. Current piezoelectrics exhibit either large charge (d33) or voltage (g33) coefficients but not both simultaneously, and yet the maximum energy density for energy harvesting is determined by the transduction coefficient: d33*g33. In prior piezoelectrics, an increase in polarization usually accompanies a dramatic rise in the dielectric constant, resulting in trade off between d33 and g33. This recognition led us to a design concept: increase polarization through Jahn-Teller lattice distortion and reduce the dielectric constant using a highly confined 0D molecular architecture. With this in mind, we sought to insert a quasi-spherical cation into a Jahn-Teller distorted lattice, increasing the mechanical response for a large piezoelectric coefficient. We implemented this concept by developing EDABCO-CuCl4 (EDABCO = N-ethyl-1,4-diazoniabicyclo[2.2.2]octonium), a molecular piezoelectric with a d33 of 165 pm/V and g33 of ~2110 × 10−3 V m N−1, one that achieved thusly a combined transduction coefficient of 348 × 10−12 m3 J−1. This enables piezoelectric energy harvesting in EDABCO-CuCl4@PVDF (polyvinylidene fluoride) composite film with a peak power density of 43 µW/cm2 (at 50 kPa), the highest value reported for mechanical energy harvesters based on heavy-metal-free molecular piezoelectric.

Broadband Achromatic Quarter-Waveplate Using 2D Hybrid Copper Halide Single Crystals

“…An orthorhombic unit cell of PEA 2 CuCl 4 was determined from SCXRD, which showed a layered structure composed of inorganic octahedra and organic cation layers, as illustrated in Figure a . The 3d 9 electronic configuration of Cu 2+ gives rise to significant JT distortion. − As shown in Figure b, the weak absorption feature induced by the d–d transition of the copper chloride octahedra can be observed in the NIR (800–1000 nm) region. , The JT distortion plays a crucial role in reducing the energy and results in elongated copper halide octahedra, enabling anisotropic lattice distortions in both out-of-plane and in-plane directions . The presence of in-plane structural anisotropy is essential for generating in-plane optical birefringence which is still challenging for common 2D hybrid halide perovskites.…”

Review of Piezoelectric Properties and Power Output of PVDF and Copolymer-Based Piezoelectric Nanogenerators

“…In the columns labeled power density, loading, resistor, Xc, and % β-phase are the electrical power produced by the PENG per unit area, loading conditions on the PENG during the power measurement, the value of the external resistor connected to the PENG during power measurements, degree of crystallinity, and percentage of % β-phase in the total composite (including amorphous regions), respectively. The power output of the PENGs is compared based on power density divided by the product of loading force and frequency to account for operating conditions [79]. Tables 3-5 also follow this convention.…”

“…Wang et al added 10% piezoelectric EDABCO-CuCl 4 (EDABCO = N-ethyl-1,4diazoniabicyclo[2.2.2] octonium) nanoparticles to a PVDF matrix [79]. In contrast to pure PVDF, the introduction of EDABCO-CuCl 4 nanoparticles resulted in an enhancement, with a two-fold increase in output voltage (OC), a three-fold increase in current density (SC), and a remarkable twenty-eight-fold increase in output power.…”

Intrinsic Ferromagnetic Semiconductors with High Saturation Magnetization from Hybrid Perovskites

“…[ 25 ] Particularly, 2D hybrid perovskite combines the tunable magnetic properties of inorganic components with the structural diversity of organic components, making them an excellent platform for designing and synthesizing novel functional materials. Spin‐polarized photoluminescence in chiral hybrid perovskite, [ 26–27 ] large piezoelectric response [ 28 ] and ferroelectric switching [ 29 ] have been demonstrated in 2D hybrid perovskites, highlighting their potential for creating new functional materials. Despite much attention on the magnetic properties of hybrid perovskite, very few ferromagnetic materials based on perovskite structure have been prepared so far.…”