Enhancement of High-Temperature Triboelectric Performance of Polyimide Nanofibers by Introducing Fluorinated Monomers

Triboelectric nanogenerators (TENGs) are typically constrained to operate below 200 °C due to the thermionic emission effect and material degradation at high temperatures. Herein, high-temperature-resistant fluorinated polyimide nanofibers (4,4′-(hexafluoroisopropylidene) diphthalic anhydride-4,4′-oxidianiline/2,2″-bis(trifluoromethyl)benzidine, 6FDA-ODA/TFDB) were designed to mitigate the thermionic emission effect through the introduction of trifluoromethyl (−CF3) groups. 6FDA-ODA/TFDB nanofibers exhibited a fine fiber structure and a large highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap, which enhanced its effective contact area and maintained more localized states for charge transfer. The TENG based on 6FDA-ODA/TFDB nanofibers generated a voltage of 33.72 V at room temperature, which was 2.60 and 1.69 times higher than those of pyromellitic dianhydride-ODA (PMDA-ODA) and 6FDA-ODA nanofibers, respectively. More importantly, 6FDA-ODA/TFDB nanofibers maintained 19.61% (6.61 V) of the initial voltage even at 300 °C and were still able to stably charge the capacitors and lit up 20 light-emitting diodes (LEDs), demonstrating great potential for high-temperature applications. This work provides an effective modification method to enhance the triboelectric performance and thermal charge stability of nanofiber membranes.