Highly Integrated Triboelectric Nanogenerator for Efficiently Harvesting Raindrop Energy

The emergence of triboelectric nanogenerators (TENG) has promoted the harvesting of raindrop energy, which mainly includes the kinetic energy and electrostatic energy generated during the fall of raindrops. However, maximizing the use of such energy is quite challenging due to its fragmentary characteristics. A highly integrated TENG is developed that can efficiently collect raindrop energy. It consists of a saccular contact-separation mode TENG (SCS-TENG), a freestanding TENG with interdigitated electrodes (I-TENG), and strip-shaped I-TENGs (SI-TENG). At a water drop rate of 22 mL s(-1), it demonstrates a striking increase with short-circuit current of 95.4 mu A and open-circuit voltage of 42.2 V, whereas the output of single TENGs is only 8.1 mu A/5.9 V (SI-TENG), 75.1 mu A/29.3 V (I-TENG), and 9.1 mu A/28.9 V (SCS-TENG), respectively. Moreover, it can be used in self-powered devices and as a rain alarm system. It not only provides a promising step toward the efficient collection of raindrop energy but also provides a new perspective for the research and development of self-powered sensors based on rainfall.