Development and outlook of high output piezoelectric nanogenerators

With the rapid development of the Internet of things (IoT), wearable electronics, how to power them has been a great challenge, as the traditional powering method via batteries suffers from the problems of batteries’ limited capacity and lifetime. Piezoelectric nanogenerators (PENGs) is one of the most promising solutions, as they can convert the ubiquitous and versatile mechanical energy into electricity. Since its invention in 2006, the PENG has achieved tremendous progress. Its voltage has increased from a few millivolts to hundreds of volts, and its current has increased from nanoampere to hundreds of microamperes. In this review, the working mechanisms of PENGs are discussed at first to point out how to improve PENGs’ output theoretically. Then, according to the theoretical analysis, concrete methods including developing piezoelectric materials with high electromechanical response, structural optimization to scale up the electricity generated by individual nanomaterials are discussed. Next, considering the mismatch between the pulse signal generated by PENGs and the stable power supply requirement for conventional electronics, power extraction circuits are discussed. Finally, an outlook of future developments of high output PENGs is given.