Ultrahigh output charge density achieved by charge trapping failure of dielectric polymers

Abstract

Charge density is a critical parameter for evaluating the output performance of a triboelectric nanogenerator (TENG). The charge excitation (CE) strategy is currently a prefered method for boosting output charge density. However, a high charge density leads to air breakdown. Exploring physical behaviors behind the air breakdown is the top priority for utilizing the CE strategy for achieving higher charge density. Here, the directional deposition of air ionized charge on a dielectric film surface and its consequent shielding effect on a charge excitation TENG (CE-TENG) are reported systematically. The charge trapping failure effect obtained by regulating the carrier trap state of a dielectric polymer ensures that the actual output efficiency of the CE-TENG reaches 100%. Consequently, a record-high stable charge density of 4.13 mC m⁻² for a contact-separation TENG is achieved in the atmospheric environment using the carbon powder–polyvinylidene difluoride composite film. Meanwhile, this work also provides important insight into charge trapping of dielectric polymers in the TENG field, and proposes an effective technology for quantifying trap states of dielectric polymers, which has far-reaching implications for guiding material selection of varied TENGs.