Nanogenerators were first invented by Zhong Lin Wang at the Georgia Institute of Technology in 2006, based on the piezoelectric effect, with the aim of converting wasted small-scale mechanical energy into electricity. Later, the field of nanogenerators has been expanded to include the triboelectric effect and the pyroelectric effect. Considering the recent growth of the internet of things (IoTs), a variety of electronic devices, such as sensors, actuators, and wireless transmitters/receivers, have been developed, which only consume power on the microwatt (μW)–milliwatt (mW) scale with high sustainability. Unlike previous battery power supplies, nanogenerators are an effective way to power these electronic devices and realize self-powering systems using the energy provided by the working environment.
During the past 10 yr, many researchers have developed various types of nanogenerators adapted for various applications, with many advantages such as high power output, flexibility, compactness (“all-in-one” design), light weight, cost-effective operation, and even excellent interfaces with a wide range of storage devices. These systems are ultimately targeting sustainable power source solutions in the microwatt (μW) to even gigawatt (GW) range. Their potential applications include smart/wearable/portable electronics, the internet of things (IoT), biomedical devices, sensor networks, and smart-grid systems.
Building on this background, this special issue of APL materials is devoted to research perspectives and reports on recent advances in the development of various nanogenerators, including representative piezoelectric, triboelectric, and thermoelectric devices, as well as their advanced material characterizations and various modes and mechanisms of device operation. We also suggest more practical guidelines to further develop these research concepts into manufacturing technologies. We hope that innovative nanogenerators with superior energy harvesting efficiency can be applied as practical energy devices in the future.