Coexistence of Contact Electrification and Dynamic p-n Junction Modulation Effects in Triboelectrification.

The triboelectric effect occurs when two dissimilar materials are in physical contact, attributed to the combination of contact electrification (CE) and electrostatic induction. It has been extensively explored for the development of high-performance triboelectric nanogenerators (TENGs). In this paper, we report on, besides the CE-related charge generation, an additional charge generation phenomenon associated with the modulation of the p-n junction when two semiconductor materials [methylammonium lead iodide (MAPI) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)] are put in contact and separated dynamically. The electrical outputs generated by the CE effect are determined by the surface potential difference between the two friction materials, while the ones induced by the p-n junction modulation are determined by the dynamic variations in the depletion widths of the two semiconductor friction materials. The outputs generated by the CE effect and the p-n junction effect are well separated in time scale; the p-n junction modulation contributes ∼20% of the total charge generated and could be varied by changing the chemical composition of the semiconductors. The results may provide an alternative method for the development of high-performance TENGs by utilizing this additional p-n junction modulation effect.