A β-cyclodextrin enhanced polyethylene terephthalate film with improved contact charging ability in a high humidity...

Moisture in the environment can severely decrease the contact charging properties of polymers, which usually reduce the output of solid-solid triboelectric nanogenerators (TENGs), hindering their further practical applications. To solve this problem, in this paper we fabricated a new type of polyethylene terephthalate (PET) based TENG, which can work stably in a high humidity environment with high output performance. The surface of the PET film is modified with β-cyclodextrin to introduce hydroxyl groups, which increase the ability to form hydrogen bonds with water molecules in a high humidity environment, immobilizing water molecules to participate in contact charging. Since water molecules are a more positive material, the PET film combined with water molecules will acquire more positive charges during the contact charging process, which will greatly increase the electrical output of PET-based TENGs. Different from the PET film-based TENG without hydroxyl on the surface, the electrical output of the β-cyclodextrin-modified PET-based TENG increases with the increase of environmental humidity. The circuit current (I _sc) of the TENG increases from 3.7 μA to 16 μA when the humidity increases from 15% to 95%. Moreover, the dielectric properties of the PET film increase due to the introduction of amino groups in β-cyclodextrin, which causes the I _sc of the TENG to increase by 3.7 times at 15% RH. This strategy highly expands the application scope of TENGs for energy harvesting and self-powered sensors in high humidity environments, especially in cloudy and foggy days or under water and sweat conditions.