Direct current triboelectric nanogenerator nexus: Fundamentals to applications in self-powered systems

Direct Current Triboelectric Nanogenerators (DC-TENGs) have emerged as a promising technology for sustainable energy harvesting, enabling the direct conversion of mechanical energy into a stable DC output. Unlike traditional Alternating Current Triboelectric Nanogenerators (AC-TENGs), which require rectification, the output of DC-TENGs simplify system integration, thereby making them ideal for low-power devices such as wearable electronics, sensors, and Internet of Things (IoT) systems. This review highlights the recent progress in DC-TENGs, focusing on their fundamental working mechanisms, including those based on dual and electrostatic breakdown effects, material optimization, and structural enhancements. Key challenges in the field, which include material durability, efficiency of energy conversion, charge retention, and environmental sensitivity are explored in detail. In addition, future directions emphasize the development of advanced triboelectric materials, hybrid energy harvesting systems, scalable fabrication techniques, and the adaptation of DC-TENGs to a diverse range of environmental conditions. As a result of recent research and innovation, DC-TENG technology is well positioned to play a pivotal role in the next generation of energy harvesting solutions, providing a path toward decentralized, autonomous and self-sustaining power systems.