Designable Skin-like Triboelectric Nanogenerators Using Layer-by-Layer Self-Assembled Polymeric Nanocomposites

An ultra-thin, stretchable, and transparent hydrogen-bonded poly(ethylene oxide) and poly(acrylic acid) ([PEO/PAA]n) bilayer (BL) positive triboelectric film was developed using a low-cost and eco-friendly layer-by-layer method. [PEO/PAA]n films exhibited remarkable output performance, enabling designability, foldability, and sustainability for versatile application of triboelectric nanogenerators (TENGs). The dependence of TENG behaviors on thickness was investigated by varying the number of BLs in [PEO/PAA]n films. It was demonstrated that a 1.6-μm-thick [PEO/PAA]20 TENG resulted in an optimal electrical output performance of 303 V and 36.1 mA m-2, owing to a higher affinity for electron donation and the lowest work function. A free-standing (FS) skin-like [PEO/PAA]100 TENG was designed for shape-adaptive kirigami-type nanogenerators, exhibiting ∼100% ultra-high transparency, ∼900% super-stretchability, and extraordinary foldability to 1/32 its original size. Thus, FS-TENG could be attached to the skin, a wall, or the insole of a shoe, showing an output of 321, 501, and 319 V, respectively, enough to simultaneously turn on 39 green LEDs by manually tapping or running.