Regulation of deep and shallow hole/electron trap states and charge conducting behaviors of dielectric tribo-materials for maximizing retained charges

Abstract

Recently, ultra-fast and high-efficiency charge self-injection technology (UH-CSI) utilizing the charge excitation strategy has effectively increased the charge density of triboelectric nanogenerators (TENGs). However, the air breakdown effect caused by excessive injection charge and the charge de-trapping effect resulting from the shallow trap of the polymer leads to severe charge dissipation. Herein, we utilize the HUSCI strategy to quantify the ability of 30 conventional tribo-materials to trap and de-trap positive/negative charges and reveal that the polymer's group composition influences trap states. Specifically, the density and proportion of deep and shallow hole/electron trap states determine the storage and dissipation of injected charges. Moreover, we identify three paths for dynamic charge dissipation and propose optimizing trap distribution and constructing a charge transport and blocking layer to suppress dissipation. Finally, the modified P(VDF-TrFE) film, with reasonable doping of SiO₂ and MoS₂, achieves a high retained charge density of 3.88 mC m⁻², and the charge dissipation rate is reduced by 50%, setting a new record for material modification. Surprisingly, the high trap state density of PVDF results in an ultra-high injected charge density of 26.2 mC m⁻². This study provides a fundamental methodology for quantifying charge trapping in dielectric materials and suppressing charge de-trapping.