Liquid doping materials as micro-carrier of functional molecules for functionalization of triboelectric materials and flexible triboelectric nanogenerators for energy harvesting and gesture detection

The modification or functionalization of triboelectric materials is of great importance for improving triboelectric nanogenerator's triboelectric performance. Traditionally, chemical introduction was the major method for functionalization of TENG materials which relied on certain reactive molecules and complex chemical process. The variety of functionalization was limited as majority functionalization molecules such as halogens are not chemical reactive. Here, high permittivity liquid was dispersed in polydimethylsiloxane (PDMS) matrix by emulsion mixing and regarded as functional molecules micro-carrier for functionalization of triboelectric materials. Due to the solubility of liquid, functionalized PDMS composite could be facilely fabricated by corresponding functional additive dissolved liquid, avoiding functional additive's necessity of chemical reactivity and indicating great extensibility in functionalized triboelectric materials. Fluoroethylene carbonate (FEC) additive for fluorine functionalization and benzyl chloride additive for chloride functionalization were studied for demonstration of this concept. The PDMS composite possessed high permittivity and functional property synchronously and resulted enhancement of 5.7-fold in output voltage, 5.4-fold in current and 44.8-fold in power density as compared with pristine PDMS, which was obtained by fluorine functionalized composite, PDMS-FHD45. This work demonstrated that functional additive liquid doping composite was a promising method for functionalization of triboelectric materials for great extensibility.