Two new molecular organic−inorganic hybrid halogenometallates [BnNMe 2 R]CdBr 4 (Bn = benzyl; 1: R = Me; 2: R = n-Pr) have been synthesized and found to crystallize in the acentric crystal systems suitable for ferroelectric behavior. Both these compounds exhibit well-resolved rectangular polarization vs electric field (P−E) hysteresis loops at room temperature for their polycrystalline thin films. Compounds 1 and 2 exhibited fairly high remnant polarization (P r ) values of 18.59 and 14.24 μC cm −2 , respectively. Moreover, flexible composite thin films of these halogenometallate salts with poly-(dimethylsiloxane) (PDMS) were prepared and employed as mechanical energy-harvesting devices using an impact test setup operating at a frequency of 25 Hz and an applied force of 40 N. The maximum output voltages of 52.9 and 63.8 V have been recorded for the PDMS-fabricated devices of 5 wt % of 1 and 10 wt % of 2, respectively. Also, the obtained power densities of 13.8 and 37.1 μW cm −2 for the respective 5 wt % 1−PDMS and 10 wt % 2−PDMS devices are much higher than all known devices made up of organic− inorganic hybrid materials embedded in PDMS. The energy harvested from these devices was further utilized to charge a capacitor through a full wave-bridge rectifier.

A new binary organic salt diphenyl diisopropylamino phosphonium hexaflurophosphate (DPDP⋅PF ) was shown to exhibit a good ferroelectric response and employed for mechanical energy harvesting application. The phosphonium salt crystallizes in the monoclinic noncentrosymmetric space group Cc and exhibits an H-bonded 1D chain structure due to N-H⋅⋅⋅F interactions. Ferroelectric measurements on the single crystals of DPDP⋅PF gave a well-saturated rectangular hysteresis loop with a remnant (P ) polarization value of 6 μC cm . Further, composite devices based on polydimethylsiloxane (PDMS) films for various weight percentages (3, 5, 7, 10 and 20 wt %) of DPDP⋅PF were prepared and examined for power generation by using an impact test setup. A maximum output peak-to-peak voltage (V ) of 8.5 V and an output peak-to-peak current (I ) of 0.5 μA was obtained for the non-poled composite film with 10 wt % of DPDP⋅PF . These results show the efficacy of organic ferroelectric substances as potential micropower generators.

Organic−inorganic ABX 3 hybrids with perovskite structures have drawn enormous attention owing to their intriguing chemical variability, structural tunability, and diversity of application-worthy properties. Herein, we report the synthesis of a new neutral ABX 3 hybrid ferroelectric compound [Me 3 NCH 2 CH 2 OH]CdCl 3 (1), which exhibits a 1D chain structure of edge-sharing CdCl 5 O octahedra that are connected to cationic [Me 3 NCH 2 CH 2 OH] + units via its peripheral OH functionality. The single-crystal X-ray diffraction analysis of the compound at 363 K reveals the conversion of 1 to its coordination isomer 1′, in which the anionic chain consists of face-sharing CdCl 6 octahedra and the cations are uncoordinated. The piezoresponsive force microscopy analysis performed on a single crystal of 1 confirms the existence of polarizable domains in it. The ferroelectric P−E loop measurements on 1 show a high remnant polarization value of 17.1 μC cm −2 . Composite devices based on 1 and polydimethylsiloxane (PDMS) prepared with varying wt % compositions are examined for mechanical energy harvesting applications. The highest open-circuit voltage of 55.2 V and a maximum power density of 70.9 μW cm −2 at an optimal load of 4 MΩ were obtained for the 15 wt % 1−PDMS device. The harvested energy is shown to be effective for capacitor charging and light-emitting diode (LED) flash lighting applications.

Organic–inorganic hybrid ferroelectrics are an exciting class of molecular materials with promising applications in the area of energy and electronics. The synthesis, ferroelectric and piezoelectric energy harvesting behavior of a 3d metal ion‐containing A4BX6 type organic–inorganic hybrid salt [Ph3MeP]4[Ni(NCS)6] (1) is now presented. P‐E hysteresis loop studies on 1 show a remnant ferroelectric polarization value of 18.71 μC cm−2, at room temperature. Composite thermoplastic polyurethane (TPU) devices with 5, 10, 15 and 20 wt % compositions of 1 were prepared and employed for piezoelectric energy harvesting studies. A maximum output voltage of 19.29 V and a calculated power density value of 2.51 mW cm−3 were observed for the 15 wt % 1‐TPU device. The capacitor charging experiments on the 15 wt % 1‐TPU composite device shows an excellent energy storage performance with the highest stored energies and measured charges of 198.8 μJ and 600 μC, respectively.