KPFM Study of Flexible Ferroelectric Polymer/Water Interface for Understanding the Working Principle of Liquid–Solid Triboelectric Nanogenerator

Abstract In the present work, the triboelectric phenomenon is explored in the ferroelectric polymer (ZnO‐PVDF film) surface when water drops fall on it. Using Kelvin probe force microscopy (KPFM), it is found that negative charges are generated on the surface of the film as the water drop comes into contact with the ZnO‐PVDF film, and the induced charges are found to stay on the surface for about 5 min. It is also observed that when subsequent water drops fall on the polymer surface, the charge remains almost constant. Based on the KPFM results, a mechanism for electricity generation in liquid–solid interface triboelectric nanogenerator (LSTENG) is proposed. An LSTENG has been fabricated using ZnO‐PVDF film, which shows an open‐circuit voltage of ≈1.3V and a short circuit current of ≈0.34 µA. The electrical characteristics of the LSTENG device agree with the proposed mechanism.