Triboelectric nanogenerators (TENGs) are intriguing mechanical energy-harvesting devices that could power small portable devices and detectors or charge batteries.1 TENGs can also act as selfpowered sensor elements for mechanical displacement, chemical or acoustic sensors, and biomedical monitors. The working principles of TENG are based on friction-related contact electrification. Most commonly, a TENG consists of two connected conductive electrode layers from which at least one is covered with a polymer insulator. These two surfaces from distinct materials are then contacted and separated, creating opposite sign net charges on the surfaces, which in turn induce charges on underlying conductive electrodes. During separation the electric potential difference is established, and electrons are driven to flow between the two electrodes in order to balance the electric potential difference2 .