Mylar Interlayer-Mediated Performance Enhancement of a Flexible Triboelectric Nanogenerator for Self-Powered Pressure Sensing Application

Abstract

A triboelectric nanogenerator (TENG) is a green energy harvester that transforms mechanical energy from the surroundings and body movements into useful electrical energy by the combined effect of triboelectrification and electrostatic induction. Here, we have developed a flexible organic–inorganic film-based contact separation mode TENG with polyvinyl butyral (PVB) and indium oxide (IO) films as contact materials. A biaxially oriented polyethylene terephthalate (BoPET) film (known as “Mylar”) has been used as the charge transition-blocking interlayer between the PVB triboelectric layer and the electrode, which prevents the recombination of generated charges with the interfacial charges on the electrode and thereby enhances the electrical output performance. The fabricated flexible PVB-IO TENG having a contact area of 4 cm2 and a separation gap of 5 mm generates an output voltage and a short-circuit current density of ∼700 V and ∼1.52 mA/m2, respectively. An enhancement of ∼85-fold in the peak power density is obtained for the PVB-IO TENG with the BoPET layer at a load resistance of 200 MΩ in comparison with the one without the BoPET interlayer. The as-fabricated device was used for capacitor charging and powering electronic gadgets such as digital thermometers, calculators, and LEDs. Also, the developed PVB-IO TENG has been demonstrated for the mechanical energy scavenging from human motions such as finger tapping, palm tapping, finger bending, and elbow bending. Moreover, the PVB-IO TENG was structurally modified into a self-powered pressure sensor by reducing its contact area and separation gap, which exhibits an excellent sensitivity of ∼4.38 V/kPa in the pressure range from 0.5 to 16 kPa.