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 from 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=Bo exp(−bV−1/2). With increasing frequency, the EL intensity dramatically increases at lower frequencies (<1000 Hz), and then increases gradually at higher frequencies (>1000 Hz).