Effect of ultraviolet light and ozone on electrification performance of polymers

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(O-3), 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 O-3. Additionally, we studied the photo-excitation electrification performance of polymers under UV light and O-3. It is found that polymers can be positively charged under UV light, and the photoexcitation electrification can be further enhanced by O-3. Meanwhile, the photoelectron excitation depends on the electron-withdrawing(EW) ability of polymers. Further, the photoelectron excitation model involving the photoexcitation and the change of the highest occupied energy levels of electrons is proposed to explain the effect of UV light and O-3 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.