Synthesis and characterization of thin film electroluminescent devices all-prepared by ultrasonic spray pyrolysis

Abstract

Alternating current thin film electroluminescent devices have been fabricated using aluminum-doped zinc oxide (ZnO:Al) as transparent conducting layer, aluminum oxide (Al2O3) as insulating layers, and manganese-doped zinc sulfide (ZnS:Mn) as electroluminescent layer. All these films were deposited by the ultrasonic spray pyrolysis technique at the same temperature (450°) on glass substrates, forming a standard MISIM (metal–insulator–semiconductor–insulator–metal) configuration. The electroluminescence of MISIM devices with a total thickness of ~1330nm was investigated by applying a sinusoidal voltage with a frequency of 10kHz. The devices showed orange-emission spectra centered at approximately 570nm, characteristic of 4T1→6A1 radiative transitions of Mn2+ ions in the ZnS host, with a sharp intensity increase upon increasing the root mean square voltage above a threshold of 25V and a rapid saturation for voltages higher than 38V. The electroluminescent emission of these MISIM structures can be observed with the naked eye under ambient illumination.