Investigation of Mechanoluminescent Light-Emitting Devices Based on ZnS:Cu Composite Embedded Elastomer Film

A mechanically driven light-generating composite flims consisted of ZnS:(Cu,Al) and polydimethylsiloxane (PDMS) were fabricated by spin coating method. Effects of mechanical stresses on the structural, optical properties of composite films were investigated. X-ray diffraction(XRD) measurements showed the ZnS:(Cu,Al) microparticle based composite films showed a hexaginal zinc blende type crystal peaks without any other distinguishable phase. Field emission scanning electron microsope (FE-SEM) images showed that the ~ 900 um thick composite films fabricated and the mixed ZnS:(Cu,Al) microparticles were mostly surrounded by PDMS matrix. The mechanoluminescence intensity and color of composite films were strongly related to the external mechanical stress. The mechanoluminescence intensity increased with increasing mechanical stress and a color of the ZnS:(Cu,Al) based composite films shifted from green to blue [Commission internationale de L'Eclairage (CIE) color coordinates of (0.225, 0.444) to (0.171, 0.304)] as the increased mechanically stress. The best brightness of the composite films was 140 cd/m 2 when it was exposed to external gas flow of 700 kPa.