Mesoporous surface control of PVDF thin films for enhanced piezoelectric energy generation

Highlight
• We developed a novel and facile method to increase piezoelectric output of PVDF films by utilizing porous surface on the top of conventional films.
• By controlling the volume ratio of mixed organic solvents, we can achieve controlled pore formation and conversion of a polymer from liquid to solid state.
• We achieved high PVDF material crystallinity, compressibility and charge collecting area through porous structure.
• We increased the piezoelectric efficiency through nanostructuring while maintaining mass producibility.

We demonstrate that nanostructured thin films play a significant role in compact energy harvesting polyvinylidene fluoride (PVDF) nanogenerators. In this work, we introduced a surface control technique for preparing mesoporous PVDF thin films toward high piezoelectric output. We demonstrated that the morphology of the film could be controlled by varying the solvent evaporation rate. The material crystallinity was experimentally confirmed by X-ray diffraction (XRD) and differential scanning calorimeter (DSC) measurement. The multilayer PVDF structure with porous surface significantly increased the compressibility and charge collecting area which contributes to the significant output enhancement. The piezoelectric output increased 100% with the modified mesoporous layer. The charging capacity increased 107% compared with the same thickness solid PVDF film.