Direct current triboelectric nanogenerators: a review

Abstract Rapid advancements in the Internet of things (IoT) have revolutionized the world by creating a proliferation of low-power wireless devices and sensor nodes. The issue of powering these devices remains a critical challenge as they require a regulated direct current (DC) supply for their operation. Mechanical energy scavenging mechanisms are viewed and promoted as renewable powering solutions for low-power electronics. However, a majority of these energy harvesting mechanisms generate alternating current (AC). Converting AC to DC is a critical issue as it involves using a rectifier, which is not a preferred option considering additional circuitry, power requirements, and the significant threshold voltage of even the most state-of-the-art diodes. DC triboelectric nanogenerators (DC-TENG) have emerged as a direct powering solution, incorporating strategies like electrostatic breakdown, mechanical switching, and dynamic Schottky junction to generate a unidirectional current. Based on these strategies, different topologies for DC-TENG devices have been developed by researchers over time. Since its inception in 2014, the study on DC-TENG has rapidly emerged and expanded. This article reviews the progress associated with DC-TENG mechanisms and topologies, presents a theoretical and comparative study of these mechanisms, and highlights their applications. This article also examines the challenges, recent advancements, and future research prospects in this domain.