Improving the Performance of a Triboelectric Nanogenerator by Using an Asymmetric TiO2/PDMS Composite Layer

To improve the output power of the polydimethylsiloxane (PDMS)-based triboelectric nanogenerators (TENGs), we fabricated an asymmetric TiO2/PDMS composite film in which a pure PDMS thin film was deposited as a capping layer on a TiO2 nanoparticles (NPs)-embedded PDMS composite film. Although in the absence of the capping layer, the output power decreased when the content of TiO2 NPs exceeded a certain value, the asymmetric TiO2/PDMS composite films showed that the output power increased with increasing content. The maximum output power density was approximately 0.28 W/m2 at a TiO2 content of 20 vol.%. The capping layer could be responsible not only for maintaining the high dielectric constant of the composite film but also for suppressing interfacial recombination. To further improve the output power, we applied a corona discharge treatment to the asymmetric film and measured the output power at a measurement frequency of 5 Hz. The maximum output power density was approximately 78 W/m2. The idea of the asymmetric geometry of the composite film should be applicable to various combinations of materials for TENGs.