Piezoelectric Energy Harvesting from a Ferroelectric Hybrid Salt [Ph 3 MeP] 4 [Ni(NCS) 6 ] Embedded in a Polymer Matrix

Nonlinear Optical Glass-Ceramic From a New Polar Phase-Transition Organic-Inorganic Hybrid Crystal

Melt-quenched glasses of organic-inorganic hybrid crystals, i.e., hybrid glasses, have attracted increasing attention as an emerging class of hybrid materials with beneficial processability and formability in the past years. Herein, we present a new hybrid crystal, (Ph₃ PEt)₃ [Ni(NCS)₅ ] (1, Ph₃ PEt⁺ =ethyl(triphenyl)phosphonium), crystallizing in a polar space group P1 and exhibiting thermal-induced reversible crystal-liquid-glass-crystal transitions with relatively low melting temperature of 132 °C, glass-transition temperature of 40 °C, and recrystallization on-set temperature of 78 °C, respectively. Taking advantage of such mild conditions, we fabricated an unprecedented hybrid glass-ceramic thin film, i.e., a thin glass uniformly embedding inner polar micro-crystals, which exhibits a much enhanced intrinsic second-order nonlinear optical effect, being ca. 25.6 and 3.1 times those of poly-crystalline 1 and KH₂ PO₄ , respectively, without any poling treatments.

Discrete Molecular Copper(II) Complex for Efficient Piezoelectric Energy Harvesting Above Room-Temperature

Developing robust, wearable, and biocompatible energy harvesting devices with bulk oxides (ceramics and perovskites) is extremely hard to achieve due to their zero mechanical flexibility, heavy metal toxicity, and tunability of properties. Alternatively, discrete inorganic complexes can be an excellent choice to overcome the above-stated issues, thanks to appropriate molecular engineering. Herein, we report an above-room-temperature ferroelectric discrete molecular complex [Cu(L-phe)(bpy)(H₂ O)]PF₆ ⋅H₂ O (1) which is suitable for piezoelectric energy harvesting due to its large values of piezoelectric co-efficient (d₃₃ =10 pm V^-1 ) and spontaneous polarization (P_s =1.3 μC cm^-2 ). Among the devices prepared with the composite films of polyvinyl alcohol (PVA) and various weight % composition of 1, the 10 Wt % composite shows the highest output voltage of 8 V, a power density of 0.85 μW cm^-2 , and output current of 5 μA, which is highest for any discrete inorganic complex reported to date.

Exploring Helical Peptides and Foldamers for the Design of Metal Helix Frameworks: Current Trends and Future Perspectives

Flexible and biocompatible metal peptide frameworks (MPFs) derived from short and ultra-short peptides have been explored for the storage of greenhouse gases, molecular recognition, and chiral transformations. In addition to short flexible peptides, peptides with specifically folded conformations have recently been utilized to fabricate a variety of metal helix frameworks (MHFs). The secondary structures of the peptides govern the structure-assembly relationship and thereby control the formation of three-dimensional (3D)-MHFs. Particularly, the hierarchical structural organization of peptide-based MHFs has not yet been discussed in detail. Here, we describe the recent progress of metal-driven folded peptide assembly to construct 3D porous structures for use in future energy storage, chiral recognition, and biomedical applications, which could be envisioned as an alternative to the conventional metal-organic frameworks (MOFs).

A Ferroelectric Aminophosphonium Cyanoferrate with a Large Electrostrictive Coefficient as a Piezoelectric Nanogenerator

Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A₃ BX₆ type cyanometallate [Ph₂ (ⁱ PrNH)₂ P]₃ [Fe(CN)₆ ] (1), which shows a ferroelectric saturation polarization (P_s ) of 3.71 μC cm^-2 . Compound 1 exhibits a high electrostrictive coefficient (Q₃₃ ) of 0.73 m⁴  C^-2 , far exceeding those of piezoceramics (0.034-0.096 m⁴  C^-2 ). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1-TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 μW cm^-2 .

Metal ion induced dual switchable dielectric and luminescent properties in hybrid halides

A new multi-functional organic-inorganic hybrid compound was successfully obtained by regulating metal halides. Apart from excellent luminescence properties, in particular, the introduction of a Mn halide successfully achieved a dual-switchable dielectric property, which could lead to very interesting exploration in sensors.

Efficient Piezoelectric Energy Harvesting from a Discrete Hybrid Bismuth Bromide Ferroelectric Templated by Phosphonium Cation

Bismuth containing hybrid molecular ferroelectrics are receiving tremendous attention in recent years owing to their stable and non-toxic composition. However, these perovskite-like structures are primarily limited to ammonium cations. Herein, we report a new phosphonium based discrete perovskite-like hybrid ferroelectric with a formula [Me(Ph)₃ P]₃ [Bi₂ Br₉ ] (MTPBB) and its mechanical energy harvesting capability. The Polarization-Electric field (P-E) measurements resulted in a well-defined ferroelectric hysteresis loop with a remnant polarization value of 2.1 μC cm^-2 . Piezoresponse force microscopy experiments enabled visualization of the ferroelectric domain structure and evaluation of the piezoelectric strain coefficient (d₃₃ ) for an MTPBB single crystal and thin film sample. Furthermore, flexible devices incorporating MTPBB in polydimethylsiloxane (PDMS) matrix at various concentrations were fabricated and explored for their mechanical energy harvesting properties. The champion device with 20 wt % of MTPBB in PDMS rendered a maximum peak-to-peak open-circuit voltage of 22.9 V and a maximum power density of 7 μW cm^-2 at an optimal load of 4 MΩ. Moreover, the potential of MTPBB-based devices in low power electronics was demonstrated by storing the harvested energy in various electrolytic capacitors.