Simultaneously scavenging multi-type energies via BaTiO3 film-based coupled nanogenerator with high coupling factors

Renewable energy harvesting has been a hot topic in recent years. Due to the excellent physical performance, ferroelectric materials are commonly used to fabricate coupled nanogenerators to scavenge energy such as light and thermal, but the obtained energy is insufficient and the devices are always placed in a dry and illuminated environment, which limits the application in rainy days. Here we construct a coupled nanogenerator based on BaTiO3 (BTO) ferroelectric films to simultaneously scavenge thermal, light and droplet-based mechanical energy. While the pyroelectricity is coupled with the photovoltaic effect, the obtained charge can be increased with a coupling factor of 1.19. Using the coupling of pyroelectricity, photovoltaic and triboelectricity, the output performances of coupled nanogenerators can be improved with a high coupling factor of 1.99 for energy and 3.21 for peak power. Moreover, we refined the performance indexes in Yang coupling factors and proposed a reference standard for evaluating the quality of coupled nanogenerators. This work fully exploits the application scenarios of ferroelectric films to scavenge more energy in diverse environments, and also provides a reference standard for the evaluation of coupling performance.