Materials and structures for enhancing the performance or organic light emitting devices

Abstract

A device is provided, having an anode, a cathode, and a first organic layer disposed between the anode and the cathode. The first organic layer is capable of phosphorescent emissive when a voltage is applied between the anode and the cathode. A second organic layer disposed between the first organic layer and the cathode is also provided. The second organic layer is in direct contact with the first organic layer. The second organic layer may comprise a material having the structure:M may be selected from the group Ti, Zr, Hf, Nb, Re, Sn and Ge. The substituents R1 through R10 may be selected from the group consisting of alkyl and aryl groups. Each of R1 through R10 may represent no substitution, mono-, di-, or tri-substitution. The second organic layer may comprise a material having a dipole moment less than about 2.0 debyes, such that the device has an unmodified external quantum efficiency of at least about 3% and a lifetime of at least about 1000 hours at an initial photon flux of about 10photons/sr-sec. The second organic layer may comprise a metal complex having a plurality of ligands, wherein each ligand makes the same contribution to the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the metal complex. The second organic layer may be in direct contact with the cathode, or there may be a separate organic layer between the second organic layer and the cathode. Other metal complexes having quinolate ligands may be used.