A flexible semitransparent dual-electrode hydrogel based triboelectric nanogenerator with tough interfacial bonding and high energy output

Triboelectric Nanogenerators (TENGs), as a novel tool that is capable of harnessing ubiquitous mechanical energy, have gained tremendous attention in recent years. Developing flexible and transparent TENGs with high triboelectric output performance is a major challenge towards adaptable and invisible energy harvesters. Previously developed transparent TENGs are normally used in a single electrode working mode or have relatively low output. Herein, a flexible semitransparent dual-electrode hydrogel-based TENG (DH-TENG) with high output was developed. The DH-TENG contains a thermoplastic polyurethane (TPU) tribopositive layer and a polydimethylsiloxane (PDMS) tribonegative layer. Both materials are highly transparent. NaCl containing polyacrylamide (PAM) hydrogels were used as electrodes, and polyethylene terephthalate (PET) sheets were used to provide mechanical stiffness. A benzophenone (BP) grafting method was used to enhance the interfacial bonding between hydrophobic triboelectric materials and hydrophilic hydrogels, which realized a significant improvement in tear strength of over 12 times. The DH-TENG demonstrated a high instant voltage and current of 311.5 V and 32.4 µA respectively. A maximum power density of 2.7 W m^-2was achieved on a 4.7 MO resistor. Furthermore, the DH-TENG showed a highly stable output under continuous running and demonstrated the capability to charge capacitors and power small electronics such as a timer, pedometer, and digital watch.