Simple and rapid fabrication of pencil-on-paper triboelectric nanogenerators with enhanced electrical performance.

Paper and pencil have many advantages in triboelectric nanogenerators (TENGs) in terms of low-cost, light weight, and environment friendliness. In this work, a pencil-on-paper triboelectric nanogenerator (PP-TENG) with highly enhanced performance was introduced. In order to use paper as a friction layer and improve its triboelectric performance, a simple and rapid paper-coating process was utilized with polyvinylidene fluoride (PVDF), polyvinyledenedifluoride-trifluoroethylene (PVDF-TrFE), and poly(methyl methacrylate) (PMMA) solutions. The fabrication process of the PP-TENG was completed within 10 minutes via pencil drawing of an electrode followed by a solution coating. With an optimized electrode shape, the PP-TENG showed a maximum power density of 64 mW m-2, which is more than 19 times higher than that of the uncoated paper TENG. The electrical performance of the PP-TENG was sufficient to drive a few hundred LEDs and charge various capacitors. It was maintained after the paper was folded or even crumpled. The proposed PP-TENG is expected to be utilized with other wearable electronic devices.