Materials and structures for enhancing the performance of organic light emitting devices.

Abstract

Electroluminescent devices are described which comprise an anode; a cathode; a first electrophosphorescent org. layer disposed between the anode and the cathode; and an org. enhancement layer disposed between the first org. layer and the cathode, where the org. enhancement layer is in direct contact with the first org. layer and comprises a material of formula (I) where M is a metal; R3-6 are substituents, each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, alkylaryl, CN, CF3, CnF2n+1, trifluorovinyl, CO2R1, C(O)R1, NR1R2, NO2, OR1, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl or a heterocyclic group, where each of R1 and R2 is independently selected from the group consisting of hydrogen, alkyl, alkylaryl and aryl; ring A is an arom. heterocyclic or a fused arom. heterocyclic ring with at least 1 N atom that is coordinated to the metal M, where the ring can be optionally substituted; each Z may be the same or different, and is an ancillary ligand; x is a value from 1 to the max. no. of ligands that may be attached to the metal; and x+y is ≤ max. no. of ligands that may be attached to the metal. The enhancement materials are thermally stable and have a high energy band gap. [on SciFinder(R)]