TENG are prepared in this study. After introducing initial charges on the Al 2 O 3 surface of the TENGs, the long-term evolution of surface charge quantity is investigated at different temperatures. The results show that charge variation of all the TENGs is analogous to exponential decay and is in accord with the thermionic emission model, verifying the electron transfer dominated mechanism of CE. Additionally, it is explored for the first time that the potential barrier of materials can be regulated by changing the contacting metals or dielectrics. Regulation of the barrier at high temperatures fully excludes the influence of ions from moisture and functional groups, which further indicates the dominant role played by electron transfer in CE. Surface state models for explaining barrier regulation during CE for both metal-dielectric and dielectric-dielectric pairs are proposed. This study provides a new perspective of the exploration of CE, and a novel method for further increasing or rapidly eliminating electrification of charged materials.

Contact electrification (CE) (or triboelectrification) is the phenomena where charges are produced through physical contact between two materials. Here we report the atomic featured photon emission spectra during CE between two solid materials. Photon emission provides the evidence that electron transfer takes place at the interface from an atom in one material to another atom in the other material during CE. This process is the contact electrification induced interface photon emission spectroscopy (CEIIPES). It naturally paves a way to a spectroscopy corresponding to the CE at an interface, which might impact our understanding of the interaction between solids, liquids, and gases. The physics presented here could be expanded to Auger electron excitation, x-ray emission, and electron emission in CE for general cases, which remain to be explored. This could lead to a general field that may be termed as contact electrification induced interface spectroscopy (CEIIS).

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