Universal Display Corporation
Organic electroluminescent materials and devices

Abstract:

A composition formed of a mixture of two compounds having similar thermal evaporation properties that are pre-mixed into an evaporation source that can be used to co-evaporate the two compounds into an emission layer in OLEDs via vacuum thermal evaporation process is disclosed. The first and second compounds can have an evaporation temperature T.sub.1 and T.sub.2, respectively, of 150 to 350.degree. C., and the absolute value of T.sub.1-T.sub.2 can be less than 20.degree. C. The first compound can have a concentration C.sub.1 in the mixture and a concentration C.sub.2 in a film formed by evaporating the mixture in a vacuum deposition tool at a constant pressure between 1.times.10.sup.-6 Torr to 1.times.10.sup.-9 Torr, at a 2 .ANG./sec deposition rate on a surface positioned at a predefined distance away from the mixture being evaporated, where the absolute value of (C.sub.1-C.sub.2)/C.sub.1 is less than 5%.