Engineering Al-doped ZnO/PDMS flexible triboelectric nanogenerators through SiO2 interlayer and MoS2 nanofillers for enhanced performance

Abstract

This study reports the development and optimization of a flexible triboelectric nanogenerator (TENG) using ZnO as the tribopositive layer and PDMS as the tribonegative layer for vibration energy harvesting applications. The performance of the TENG was enhanced through a series of systematic modifications. Aluminum doping (2 at.%) increased the electron concentration of ZnO from ~4 × 10¹⁶ to ~1.8 × 10¹⁹ cm⁻³ and reduced its work function from ~4.26 to ~4.19 eV, resulting in an output improvement from ~115 V/8 µA to ~210 V/18 µA. Introducing a ~100 nm SiO₂ interlayer between the ZnO and ITO electrode further enhanced the output to ~288 V/25.8 µA by reducing electron diffusion and lowering the ZnO work function to ~4.10 eV, as verified through Kelvin probe force microscopy. Additionally, incorporating 6 wt.% MoS₂ nanofillers into the PDMS layer created a nanocapacitor network, improving its triboelectric properties and increasing the TENG output to ~369 V/28.3 µA with a maximum instantaneous power density of ~1.8 mW/cm². The optimized TENG demonstrated excellent mechanical durability over 10,000 cycles and stable performance for three months, effectively powering an array of LEDs and charging commercial capacitors. These results highlight the potential of ZnO-based flexible TENGs for sustainable and durable energy harvesting in micro- and nano-electronic devices.