Ultra-High DC Current Output with Low impedance for Free-Standing Triboelectric Nanogenerator by Integrating Device Structure Design and Charge-Pumping Circuit

Energy harvesting technologies have been enormously attained over the years due to
the demand for reserve power sources instead of the battery, especially low power electronic
devices similar to self-powered sensor systems. One of the promising types of energy harvester
is triboelectric nanogenerator (TENG) that converts ambient mechanical energy into alternative
current, utilizing the principle of triboelectrification effect. Although it exhibits a high opencircuit
output voltage of up to hundreds or even thousands of volts, the output power density
and transferred charges remain relatively low due to high impedance in the transmission path,
inducing potentially unstable voltage levels upon powering. In this study, we demonstrate a
straightforward strategy to control and enhance opposite charges by integrating device structure
design with PN-junction–like characteristics in a free-standing mode, combined with an
optimized charge-pumping circuit. As a result, the fabricated TENG is capable of delivering
open-circuit output voltage and instantaneous output power density (at external output
impedance of ~1MΩ) that are increased by 3-folded and 6-folded, respectively, compared to
the conventional free-standing structure. Furthermore, to increase the surface charge density,
an optimized charge-pumping circuit was employed into the fabricated TENG, inducing ultrahigh
direct current (DC), which improve to 10-folded, compared to optimized structure. This
work provides a combined device structure design and charge-pumping circuit to obtain ultrahigh
DC and low impedance output for application in energy harvesting.