Effect of ultraviolet light and ozone on electrification performance of polymers

Highlights: • The contact electrification at solid-solid, liquid-solid, and gas-solid interface can be weakened by UV light and O₃. • Polymers can be positively charged under UV light, and the photo-excitation electrification can be further enhanced by O₃. • The relationship between the photoelectron excitation and the electron-withdrawing(EW) ability of polymer is studied. • The model involving the photo-excitation and the change of the highest occupied energy levels of electrons is proposed. Triboelectric nanogenerator (TENG) has become a promising energy harvesting system in recent years, while the electron transferring at the contact interface is a key element to decide its performance. Herein, we employed TENG to study the effect of ultraviolet (UV) light and ozone(O₃), which exists everywhere in near space, on the contact electrification(CE) of polymers. Testing results showed that the electron transfer at solid-solid, liquid-solid, and gas-solid interface can be weakened by UV light (light wavelength at 200 nm), and the inhibition can be further strengthen by O₃. Additionally, we studied the photo-excitation electrification performance of polymers under UV light and O₃. It is found that polymers can be positively charged under UV light, and the photo-excitation electrification can be further enhanced by O₃. Meanwhile, the photoelectron excitation depends on the electron-withdrawing(EW) ability of polymers. Further, the photoelectron excitation model involving the photo-excitation and the change of the highest occupied energy levels of electrons is proposed to explain the effect of UV light and O₃ on the electrification performance of polymers. The finding provides a strong evidence about the electron transfer process in the CE at solid-solid, liquid-solid, and gas-solid interface.