Wearable triboelectric nanogenerators with the reduced loss of triboelectric charges by using a hole transport layer of bar-printed single-wall carbon nanotube random networks

Wearable triboelectric nanogenerators (TENGs) are considered viable for mobile applications of self-powered electronics operating on human body but limited by relatively low output performance. In this study, the effects of interfacial layers used as hole transport layers (HTLs) which affect triboelectric charge separation on the output performance of TENGs are investigated. Comparative analyses of different interfacial layers prove that the incorporation of single-wall carbon nanotube (SWCNT) random networks into TENGs can reduce the loss of triboelectric charges. Improvements in the charge-repelling force and hole-blocking barrier at the interface between the HTL and electrode enabled the wearable TENGs to achieve output voltages of ∼760 V and currents of ∼51 μA at 3 Hz. Such advances can be realized by optimizing SWCNT-based HTL through a simple and effective bar-printing technology in an ambient atmosphere. Moreover, a practical application of the wearable TENG exhibiting a maximum instantaneous power of 19.2 mW and a power density of 0.77 mWcm−2 with a load resistance of 5 MΩ is demonstrated. Mechanical finger-tapping on wearable TENGs enables operation of small electric devices without energy storage. The utilization of SWCNT-based HTLs fabricated by effective and practical bar-printing can stimulate the development of energy-harvesting technologies based on wearable TENGs.