Extremely Foldable and Highly Porous Reduced Graphene Oxide Films for Shape-Adaptive Triboelectric Nanogenerators.

Here, a thin and foldable porous reduced graphene oxide (rGO) fabricated by a solvent casting method (SC-rGO) is introduced. The SC-rGO is superior to aluminum as a positive triboelectric material in triboelectric nanogenerators (TENGs), significantly enhancing TENG output performance. The film shows extremely foldable features, where it could be folded by 1/16 size. The electrical properties and device performance of SC-rGO are optimized varying thicknesses from 5 to 30 µm. A 30 µm thick TENG with a non-annealed SC-rGO film (STENG) shows the highest output of about 255 µW cm due to its high carrier concentration, low work function, and high surface area. After annealing, STENG performance is optimized with a 10 µm thick SC-rGO because their work functions decreases, while the corresponding carrier concentrations decrease according to the thickness of the SC-rGO films. The SC-rGO films are highly durable and stable, where their output and conductivity show negligible changes after 100 000 cycles of mechanical deformation. A large SC-rGO with a size of 13 × 3 cm is fabricated and is attached inside a person's arm to demonstrate the shape-adaptive characteristics. Consequently, 170 V is obtained and it turns on 19 green light emitting diodes by simply touching the STENG.