Organic light-emitting devices with a 2-(4-biphenyl)-5-(4-butylphenyl)-1, 3, 4-oxadiazole layer between the alpha-naphtylphenyliphenyl diamine and 8-hydroxyquinoline aluminum. - Su Zhan; Xie Ying-ge; Li Xia; Yu Tao (Microelectron. J., 2006)