Drop‐Location‐Insensitive Droplet‐Based Electricity Generator Using Polydimethylsiloxane Slippery Covalently Attached Liquid Coatings

ABSTRACT

Droplet‐based electricity generators (DEGs) offer a promising strategy for harvesting untapped water energy from sources such as rain. To ensure high energy harvesting performance, droplets must contact the surface and be rapidly detached. To enable this behavior, superhydrophobic surfaces have been considered a solution. However, conventional superhydrophobic‐DEGs often face difficulties in practical applications due to non‐uniform performance caused by droplet bouncing and splitting. Here, we introduce a polydimethylsiloxane slippery covalently attached liquid (PDMS‐SCAL) coating into a DEG platform to minimize contact line pinning and droplet rebound. The PDMS‐SCAL‐DEG exhibits high open‐circuit voltage output (162.2 ± 3.8 V) and excellent performance stability across various droplet heights, incline angles, and drop locations. In drop‐location sensitivity experiments performed 14.1 mm apart from the optimum point, only a ≤25% performance degradation was observed. Experiments on a superhydrophobic‐DEG revealed that the same conditions led to a more than 92% performance degradation. Developed PDMS‐SCAL‐DEG maintains stable energy‐harvesting performance even after 10000 energy‐harvesting cycles. The reliability of PDMS‐SCAL‐DEG was also demonstrated through field testing in rainy environments. We further confirmed the comprehensive durability, including mechanical and chemical durability. This work presents a previously unexplored DEG platform with drop‐location‐insensitive characteristics to expand the scope of DEG applications.