Low-voltage dc thin-film electroluminescence with an indium-tin-oxide/CaS : Pb/ZnS/Al structure

Abstract

A dc thin-film electroluminescent (TFEL) device has been fabricated to achieve low voltage operation and high-luminance blue emission. The device is based on an [Al/ZnS/luminescent CaS:Pb/indium-tin-oxide] structure in which electrons can be injected into the luminescent layer at high energy due to the field-induced acceleration of electron carriers within the ZnS layer. The blue-emitting CaS:Pb and ZnS layers were consecutively prepared by atomic layer deposition. Preliminary results obtained from this device indicate a threshold voltage for light emission of as low as 17 V and a higher luminous efficiency of 0.1-0.36 lm/W compared with that of CaS:Pb ac TFEL.