Highly stretchable PTFE particle enhanced triboelectric nanogenerator for droplet energy harvestings

Liquid-solid based triboelectric nanogenerator (TENG) can be widely utilized for droplet energy harvesting, in which the hydrophobicity of triboelectric layer is crucial for output enhancement. However, poor mechanical properties of hydrophobic triboelectric layers prepared in classic methods greatly limit the TENG's application. Here, a stretchable hydrophobic triboelectric nanogenerator (SH-TENG) with excellent output, and durability is devised by strongly bonding PTFE micro particles on a flexible substrate even under extreme stretching or abrasion. By synergistic enhancement of the PTFE particles on both contact-separation and charge-transfer between droplet and triboelectric layer, the transfer charge density of SH-TENG is increased to ∼4.74 × 10⁻³ C/m²·L, along with the open circuit voltage (V_OC) and short circuit current (I_SC) over 7 times and 6 times higher than TENG without PTFE modified, respectively. Moreover, under a stretching rate of 500%, the SH-TENG shows less 20% decline of its output performance to guarantee applications in flexible electronics. A miniature watch can be sufficiently powered by the SH-TENGs with total area of 0.016 m² under the simulated raindrop flow rate of 50 mL/min. With such outstanding performance and environmental adaptability, the SH-TENG can be integrated with various objects to collect droplet energy and supply electronic devices.