The related studies and applications of ZnS-based phosphorescent materials involve various aspects such as lighting, display, sensing, electronic signatures, and confidential information. Here, triboelectrification-induced electroluminescence (TIEL) of the ZnS:Cu due to the triboelectric leakage field is discovered via a gently horizontal sliding between a ZnS:Cu particle-doped polydimethylsiloxane (PDMS) film and a polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP) film, whose intensity is positively correlated with the temperature, the doping ratio of ZnS:Cu, the pressure, and the frequency. It is also demonstrated that the TIEL mainly occurs inside the bulk film, where the ZnS:Cu phosphor particles can be polarized instantaneously by the leakage electric field of triboelectrification. The polarization will lead to a tilted energy band of the ZnS, resulting in an emitting of green light due to electrons detrapped into the conduction band and recombined with holes in the impurity state. This study not only reveals great fundamental physics for understanding of luminescence induced by a simple sliding between two triboelectric materials but also indicates another way for triboelectrification to be used in advanced optoelectronic devices.
Keywords: ZnS:Cu; electroluminescence; flexible; phosphor; triboelectrification.