Photovoltaic and Piezoelectric Power Generation Characteristics of Flexible Poly(Vinylidene Fluoride-Ran-Trifluoroethylene) Thin Films

We investigated the photovoltaic and piezoelectric power generation characteristics of ferroelectric poly(vinylidene fluoride-ran-trifluoroethylene, PVDF-TrFE) thin films on flexible indium tin oxide (ITO)/polyethylene terephthalate (PET) substrates. The solar cells and piezoelectric hybrid devices provide consistent energy to extend battery life and improve self-charging. The flexible PVDF-TrFE thin films with a transmittance of about 60% in the visible region showed a remanent polarization of about 10.5 μC/cm² (2P_r ~ 21.0 μC/cm²) with excellent β-phase formation. The flexible PVDF-TrFE thin films exhibited optimal ferroelectric and piezoelectric properties by exhibiting β-phase without α-phase. Since β-phase is the phase that carries high dipole alignment of the material, which is important for maximizing power output, the performance of the material in photovoltaic and piezoelectric applications is enhanced. The PVDF-TrFE capacitor exhibited not only a piezoelectric generation characteristic with an approximate voltage of 1.1 V under compression, but also a photovoltaic generation feature with an open-circuit voltage of about 0.23 V and a short-circuit current of approximately 0.13 mA/cm².