Triboelectrification: Backflow and Stuck Charges Are Key

To understand the most intrinsic mechanism of triboelectrification (TE), a straightforward framework of TE between metal and single-crystal dielectrics is designed by utilizing both experiments and first-principles calculations. Various theoretical models on charge transfer are examined with first-principles calculations. Interestingly, the measured charge density shows a proportional relation with the interface barrier, which is in contrast with the previous theories. On the basis of the results, a backflow-stuck charge model is proposed where the charge density is determined by the amount of backflow and the remaining stuck charges at separation. We also validated this model by comparing the theoretically predicted barrier and the extracted barrier from the temperature-dependent triboelectrification. The results soundly support that backflow-stuck charges determine the charge density at TE, where the interface barrier plays a key role. The model provides a new perspective of the charge transfer mechanism on the TE and can be generally applied to TE of conventional materials.