Energy Conversion Analysis of Multilayered Triboelectric Nanogenerators for Synergistic Rain and Solar Energy Harvesting.

The triboelectric nanogenerator (TENG) is an emerging technology that offers excellent potential for the conversion of mechanical energy from rain into electricity for hybrid energy applications. However, a high-performance TENG is yet to be achieved because a quantitative analysis method for the energy conversion process is still lacking. Herein, a quantitative analysis method, termed the "kinetic energy calculation and current integration" (KECCI) method, which significantly improves the understanding of the mechanical-to-electrical energy conversion process, is presented. Based on the KECCI method, a high-performance TENG is developed by systematically optimizing a biomimetic surface structure and instant switch design, with 1.25 mA short-circuit current (I ), 150 V open-circuit voltage (V ), and a high energy-conversion efficiency of 24.89%. Furthermore, a multilayered TENG device is proposed for continuously harvesting the kinetic energy of raindrops for further improvement in the energy-conversion efficiency. Finally, the multilayered TENGs are integrated with organic photovoltaics, achieving all-weather energy harvesting. This work presents a validated theoretical basis that will guide further development of TENGs toward higher performances, which will promote the commercialization of hybrid TENG systems for all-weather applications.