Triboelectric nanogenerators with transfer-printed arrays of hierarchically dewetted microdroplets

Triboelectric nanogenerators (TENG) is of great interest as an emerging power harvester due to its simple device architecture and high efficiency. Despite development of various surface modification techniques for enhancing the performance of a TENG with a given triboelectric pair of materials, a method capable of being used universally on a variety of surfaces and improving the performance of TENGs with diverse surfaces remains a challenge. Here, we demonstrate a novel transfer-printing technique of hierarchically dewetted polymer droplets on various TENG surfaces for performance enhancement of the TENGs. Our method is based on controlled dewetting of a thin supramolecular assembled film of two end-functionalized polymer blends on a prepatterned poly(dimethyl siloxane) mold, followed by the physical pattern-transfer of arrays of the dewetted droplets consisting of supramolecular assembled nanostructures on a TENG contact surface. The hierarchically dewetted microdroplets comprising soft-etched nanopores efficiently improve the performance of a TENG by more than three times compared to one without the transferred pattern. The pattern-transfer is successfully achieved on various surfaces including not only oxides, plastics, rubbers, and metals, but also fabrics, coins, vegetables, and shells, making our approach a convenient way for enhancing the triboelectric performance of a given TENG.