Sustainable highly charged C₆₀-functionalized polyimide in a non-contact mode triboelectric nanogenerator

In this paper, we report on a new dielectric, a C60-containing block polyimide (PI-b-C60). This was realized by introducing C60 as pendent groups into a polymer backbone. When this dielectric was used in a non-contact mode triboelectric nanogenerator (TENG), it achieved high output power and reliable operation. Compared with perfluoroalkoxy alkane film-based TENGs, the TENG based on PI-b-C60 generated 4.3 times higher output power and a superior charge density of over 300 μC m-2 with a 3 times slower charge decay rate. These results are most likely due to the excellent charge-retention characteristics induced by the most negative electrostatic potential of C60 within the backbone, and these characteristics were confirmed by surface potential measurements. Furthermore, in the course of our work, two non-contact mode applications, a keyless electronic door lock system and a speed sensor with a tone wheel for a car, were developed. Without an ion injection process being needed, very sensitive and reliable operations of the speed sensor were successfully demonstrated, even under very humid conditions (∼99% RH).