A Flexible Composite Mechanical Energy Harvester from a Ferroelectric Organoamino Phosphonium Salt

A new binary organic salt diphenyl diisopropylamino phosphonium hexaflurophosphate (DPDP⋅PF₆ ) 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⋅PF₆ gave a well-saturated rectangular hysteresis loop with a remnant (P_r ) polarization value of 6 μC cm^-2 . Further, composite devices based on polydimethylsiloxane (PDMS) films for various weight percentages (3, 5, 7, 10 and 20 wt %) of DPDP⋅PF₆ were prepared and examined for power generation by using an impact test setup. A maximum output peak-to-peak voltage (V_PP ) of 8.5 V and an output peak-to-peak current (I_PP ) of 0.5 μA was obtained for the non-poled composite film with 10 wt % of DPDP⋅PF₆ . These results show the efficacy of organic ferroelectric substances as potential micropower generators.