A cathode structure of lithium quinolate (Liq)/Mg:Ag/Al was developed and device performances were investigated according to the thickness of Mg:Ag interlayer between Liq and Al. Device performances of Liq/Mg:Ag/Al were optimized at an interlayer thickness of 1.0 nm and power efficiency was enhanced by 50% by introducing Mg:Ag interlayer because of low driving voltage and high current efficiency. (C) 2008 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.