PL and EL characterizations of ZnO:Eu3+ Li+ films derived by sol-gel process

ZnO:Eu3+, Li+ films prepared by the dip-coating method were characterized by photoluminescence (PL) and electroluminescence (EL). When the ZnO:EU3+, Li+ films were excited using UV light with energy corresponding to the band-to-band excitation of the host matrix, the PL spectra showed emissions front both ZnO and EU3+ ions, while their EL spectra showed emissions only from EU3+ ions, and no emission from ZnO could be detected. It is found that the EL emission intensity B is dependent on the applied voltage, B = B-o,exp(-b V-1/2). With increasing frequency, the EL intensity dramatically increases at lower frequencies (< 1000 Hz), and then increases gradually at higher frequencies (> 1000 Hz). (c) 2007 Elsevier B.V. All rights reserved.