Hybrid-Mode Triboelectric Nanogenerator Based on Cantilever Beam for Enhanced Droplet Energy Harvesting

Droplet triboelectric nanogenerator (D-TENG) offers a promising solution to harvest the low-frequency, low-actuation-force, and high-entropy droplet energy. Conventional attempts primarily focus on electrostatic energy collection at the liquid-solid interface, leaving the substantial kinetic energy from droplet impacts largely untapped, which restricts overall performance. In this work, utilizing fluorinated ethylene propylene (FEP) film as friction materials, we construct a hybrid-mode triboelectric nanogenerator based on cantilever beam structure that integrates a droplet triboelectric nanogenerator (D-TENG) with a freestanding triboelectric-layer mode (F-TENG), to synergistically capture both electrostatic and kinetic energy from droplet impacts (referred to as DF-TENG). Triggered by small droplets, the flexible cantilever beam, rather than conventional stiff ones, can easily vibrate multiple times with large amplitude, enabling frequency multiplication of F-TENG and producing amplified output charges. Hybrid-mode structures improve charge separation efficiency by utilizing droplet impact dynamics. The results show that the composite structure improves the charge output of the device by approximately 1.9 times and increases the charging speed by about 3 times. This study highlights the potential of DF-TENG for addressing key challenges in raindrop energy harvesting, advancing TENG technology toward scalable applications in self-powered systems and liquid energy collection.