Effect of the thicknesses of asymmetric TiO2/polydimethylsiloxane films on the triboelectric output power

To improve the output voltage of the polydimethylsiloxane (PDMS)-based triboelectric nanogenerators, we investigated the effect of thicknesses of TiO2 nanoparticles (NPs)/PDMS composite films on the output power. The composite film was composed of TiO2 NPs-embedded PDMS film (base film) and pure PDMS thin film (capping layer) which was deposited on the base film. We found that the moderate thickness of the capping layer was approximately 3 μm, which is the thinnest film thickness that can completely cover the particulates exposed on the surface. The TiO2 NPs/PDMS composite films with moderate thicknesses showed a maximum output voltage of 51.4 V when the capping layer thickness was approximately 3 μm and the base film thickness was approximately 0.25 mm. Moreover, we obtained that the inverse of the output voltage is linearly proportional to the thicknesses of the capping layer and the base film.