Improved performances of organic light-emitting diodes with metal oxide as anode buffer

Abstract

We demonstrate extremely stable and highly efficient organic light-emitting diodes(OLEDs) based on molybdenum oxide ( Mo O 3 ) as a buffer layer on indiumtin oxide (ITO). The significant features of Mo O 3 as a buffer layer are that the OLEDs show low operational voltage, high electroluminescence(EL) efficiency and good stability in a wide range of Mo O 3 thickness. A green OLED with structure of ITO ∕ Mo O 3 ∕ N , N ′ -di(naphthalene-1-yl)- N , N ′ -diphenyl-benzidene (NPB)∕NPB: tris(8-hydroxyquinoline) aluminum ( Al q 3 ) :10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl- 1 H , 5 H , 11 H -(1)-benzopyropyrano(6,7-8- i , j )quinolizin-11-one (C545T)∕ Al q 3 ∕ Li F ∕ Al shows a long lifetime of over 50 000 h at 100 cd ∕ m 2 initial luminance, and the power efficiency reaches 15 lm ∕ W . The turn-on voltage is 2.4 V , and the operational voltage at 1000 cd ∕ m 2 luminance is only 6.9 V . The significant enhancement of the EL performance is attributed to the improvement of hole injection and interface stability at anode.