Natural ginkgo tree leaves as piezo-energy harvesters

Abstract

Ginkgo biloba has outlasted the dinosaurs, and is the oldest surviving tree on this planet. Here, we report for the first time the discovery of natural ginkgo tree leaves as an efficient piezoelectric energy harvester. The ginkgo leaves finalize the naturally-driven self-polarization during leaf growth, thus allowing the highly preferential alignment of the internal piezo-phase cellulose crystals. The ginkgo leaves are used directly as an effective piezoactive layer to fabricate a self-polarized, mechanically flexible, shape adaptable piezoelectric nanogenerator. The voltage output, current output, and power density reach up to 131 V cm⁻³, 2.5 μA cm⁻³, and 25.7 μW cm⁻³, respectively. The measured piezoelectric output is among the highest levels in the state-of-the-art bioorganic material based piezoelectric devices. Moreover, the ginkgo-leaf nanogenerator exhibits an ultrahigh linear piezo-sensitivity in the very small stress states. It possesses the ability for human speech recognition. As a proof of concept, the ginkgo-leaf device is employed as a self-powered wearable tactile sensor for real time monitoring of sports activities. It demonstrates great potential in athletic big data collection and analysis for intelligent sports. We propose that natural ginkgo tree leaves can be a compelling green piezoelectric material for developing a new generation of eco-friendly transient energy devices.