A method of fabricating an organic light emitting device includes forming a first electrode layer on a substrate, surface-treating the first electrode layer with CF4 plasma, forming a first common layer containing pentacene on the surface-treated first electrode layer, forming an organic light emitting layer on the first common layer, forming a second common layer on the organic light emitting layer, and forming a second electrode layer on the second common layer. The CF4 plasma treatment enhances the luminous efficiency of the organic light emitting device.