A United Triboelectrification Mechanism for Contacts between All Types of Materials

摘要

Triboelectrification for contacts between three types of materials—metals, polymers, and semiconductors—are investigated. The results show that triboelectrification is a charge exchange process between the surfaces of two friction materials, and its output is the synergetic effects of the electrostatic induction (ESI) and dynamic junction modulation (DJM). There are four current/voltage peaks in output of triboelectrification: two of them are attributed to the ESI effect and determined by the surface state densities and electron affinity difference of the materials, while the other two are associated with the DJM effect and determined by the charging exchange between the surface states and the depletion region. However, metals and polymers have no-modulation of depletion region due to their high conductivity and insulating nature, respectively, thus only two peaks induced by the ESI effect are observable no matter what types of metals and polymers are in pair for contacting. Semiconductors have a depletion region, there will be two more output current/voltage peaks induced by the junction modulation when a semiconductor is in contact with any type of materials. The observations reveal a universal triboelectrification mechanism for contacts between materials, and provide an intuitive guidance for the development of high-performance triboelectric nanogenerators.