Surface Engineering of Graphene Composite Transparent Electrodes for High-Performance Flexible Triboelectric Nanogenerators and Self-Powered Sensors.

High-performance transparent and flexible triboelectric nanogenerators (TENGs) based on graphene composite electrodes via surface engineering are proposed and demonstrated. Through modifying the CVD-grown graphene with the conductive polymer poly(3,4-ethylenedioxy-thiophene):polystyrenesulfonate (PEDOT:PSS), composite electrodes with excellent optoelectronic performances were fabricated, which exhibited a high transmittance up to 83.5% and sheet resistance of 85 Ω/□, decreasing from the initial value of 725 Ω/□. As a consequence, the output current density and power of the corresponding TENG were enhanced by 140% to 2.4 μA/cm and by 118% to 12 μW, respectively, comparing with the counterpart composed of the pristine graphene electrodes. Furthermore, the composite electrode exhibited an outstanding durability of the physical and electrical characteristics after 10 000 bending cycles and can be readily extended to a large area up to 100 cm. Such flexible, transparent, stable TENGs pave the way for the application of self-powered body sensors due to their unique characteristics, such as portability, wearability, and human compatibility.