Layer-by-layer assembly-induced triboelectric nanogenerators with high and stable electric outputs in humid environments

We introduce a layer-by-layer (LbL) assembly-induced triboelectric nanogenerator (TENG) with a high and stable electric output under a wide range of humidity conditions. In this study, highly porous (cationic poly(allylamine hydrochloride) (PAH)/anionic poly(acrylic acid) (PAA))_n multilayer films were prepared via a pH-controlled electrostatic LbL assembly with a subsequent acid treatment and were used as a mold for the triboelectric poly(dimethylsiloxane) (PDMS) replica. The electrical output of the TENGs composed of a protuberant PDMS plate and Al electrodes significantly increased based on the evolution of the nano-/micro-structured PDMS bumps. Particularly, the protuberant PDMS film molded from the porous (1.5 mg mL⁻¹ PAH/0.5 mg mL⁻¹ PAA)₂₀ multilayers displayed a high open-circuit voltage output of 242 V and a short-circuit current density of 16.2 μA cm⁻² under a compressive force of 90 N in a relative humidity (RH) of 20%. When this hierarchical PDMS surface was additionally modified by fluorine self-assembled monolayer, the voltage output and current density of the resultant TENG at the same experimental conditions were increased up to approximately 288 V and 17 μA cm⁻², respectively, exhibiting a remarkably high humidity-resistant electrical performance (16% loss of the initial voltage at 80% RH).