Investigation of The Plasma Polarization Parameters Effect on The Polyvinylidene Fluoride Film Piezoelectric Properties Used for Flexible Nanogenerators

This work is devoted to the investigation of the influence of the polarization process parameters of polyvinylidene fluoride (PVDF) film in the glow discharge plasma on its piezo properties, which determine the efficiency of flexible nanogenerators based on PVDF. The influence of the nonlinear character of the current density parameter on the d33 value of PVDF film is demonstrated. The most effective mode of plasma polarization has been determined, which allows to give a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25 \ \mu\mathrm{m}$</tex> thick PolyK film a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d_{33}$</tex> response of ~27 pC/N at a current density of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$15 \ \mu\mathrm{A}/\text{cm}^{2}$</tex> and a discharge voltage of 13 kV for 1 minute of processing. The influence of the presence of electrodes on the surface of PVDF film on the plasma polarization process was investigated at varying current density from 10 to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25 \ \mu\mathrm{A}/\text{cm}^{2}$</tex>, discharge voltage of 13 kV and treatment time of 3 min. The influence of a copper electrode on the PVDF surface facing the glow discharge plasma on the polarization process was recorded. The possibility and efficiency of plasma polarization of PVDF film with two thin-film electrodes were demonstrated for the first time, and the record value of piezo response d33 ~28 pC/N at current density of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$17,5 \ \mu\mathrm{A}/\text{cm}^{2}$</tex> was achieved for plasma polarization.