Multiaxial Molecular Ferroelectric Thin Films Bring Light to Practical Applications

Abstract

Though dominating most of the practical applications, inorganic ferroelectric thin films usually suffer from the high processing temperatures, the substrate limitation, and the complicated fabrication techniques that are high-cost, energy-intensive, and time-consuming. By contrast, molecular ferroelectrics offer more opportunities for the next-generation flexible and wearable devices due to their inherent flexibility, tunability, environmental-friendliness, and easy processability. However, most of the discovered molecular ferroelectrics are uniaxial, one major obstacle for improving the thin-film performance and expanding the application potential. In this Perspective, we overview the recent advances on multiaxial molecular ferroelectric thin films, which is a solution to this issue. We describe the strategies for screening multiaxial molecular ferroelectrics and characterizations of the thin films, and highlight their advantages and future applications. Upon rational and precise design as well as optimizing ferroelectric performance, the family of multiaxial molecular ferroelectric thin films surely will get booming in the near future and inject vigor into the century-old ferroelectric field.

2D Hybrid Perovskite Ferroelectric Enables Highly Sensitive X‐Ray Detection with Low Driving Voltage

“…Ferroelectricity of BA 2 EA 2 Pb 3 Br 10 was supported from the electric polarization ( P ) versus electric field ( E ) hysteresis loop measurements on a bulk single crystal of BA 2 EA 2 Pb 3 Br 10 at the external electric field of 20 kV cm −1 . It should be noted that normal P–E loops could be clearly observed along the crystallographic b ‐ and c ‐axes, indicating that BA 2 EA 2 Pb 3 Br 10 belongs to typical biaxial ferroelectric, which is analogous to the well‐known multiaxial ferroelectric BaTiO 3 . As shown in Figure c, a P–E loop with well‐defined rectangularity measured along b ‐axis identifies the credible ferroelectricity with moderate coercive field of 8 kV cm −1 and a decent saturation polarization of 4.5 µC cm −2 .…”

“…with an Aizu notation of 4/ mmmFmm2 according to Landau phase transition theory . Distinctly, 16 symmetric elements ( E , C 4 , C 2 , 4C 2′ , i , σh , 3S 4 , 4σv ) of point group 4/ mmm in paraelectric phase are quartered into four ( E , C 2 , 2σ v ) of mm 2 in ferroelectric phase, giving four equivalent polarization directions ( n = 16/4) . Therefore, BA 2 EA 2 Pb 3 Br 10 belongs to typical biaxial ferroelectric, which has been confirmed in the P–E loop measurements.…”

Organic enantiomeric high- T c ferroelectrics

“…Among these 88 species of potential ferroelectric phase transitions, there are 22 chiral-to-chiral ones ( Table 1) (26), providing a rational way to develop ferroelectrics. Recently, the demands of finding simple, flexible, low-cost, and environment-friendly supplements to inorganic ferroelectrics have stimulated a renaissance in molecular ferroelectrics and multiferroics (27)(28)(29)(30)(31)(32)(33)(34)(35)(36). The key obstacle of realizing a broad range of application of the emerged molecular ferroelectrics is the diverse material design in ferroelectric systems.…”

Designing and Constructing a High‐Temperature Molecular Ferroelectric by Anion and Cation Replacement in a Simple Crown Ether Clathrate

“…Af erroelectric always is af erroelastic, and the ferroelastic domains relatedt ot he boundary structure (ferroelastic domain walls) will appear before the phase transition. [52,53] Here we observed the ferroelastic domains of compound 1 by using the Atomic Force Microscope (AFM )e quipment. As shown in Figure 10, we recorded the surface morphologies of freshly crystal at 300 K ( Figure 10 ure 10 c) respectively.Obviously,there exist clear black boundaries before the phase transition (300 K).…”