Electronic devices in the context of this application are understood to mean what are called organic electronic devices, which contain organic semiconductor materials as functional materials. More particularly, these are understood to mean OLEDs.
The structure of OLEDs in which organic compounds are used as functional materials is described, for example, in U.S. Pat. No. 4,539,507, U.S. Pat. No. 5,151,629, EP 0676461 and WO 98/27136. In general, the term OLEDs is understood to mean electronic devices which have one or more layers comprising organic compounds and emit light on application of electrical voltage.
In electronic devices, especially OLEDs, there is great interest in improving the performance data, especially lifetime, efficiency and operating voltage. In these aspects, it has not yet been possible to find any entirely satisfactory solution.
A great influence on the performance data of electronic devices is possessed by layers having a hole-transporting function, for example hole-injecting layers, hole transport layers, electron blocker layers and also emitting layers. For use in these layers, there is a continuous search for new materials having hole-transporting properties.
It is known in the prior art that triarylamines can be used in these layers as materials having hole-transporting properties. The triarylamines may be monotriarylamines as described, for example, in JP 1995/053955, WO 2006/123667 and JP 2010/222268, or bis- or other oligoamines, as described, for example, in U.S. Pat. No. 7,504,163 or US 2005/0184657. Known examples of triarylamine compounds as materials having hole-transporting properties for OLEDs include tris-p-biphenylamine, N,N′-di-1-naphthyl-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) and 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (MTDATA).
Additionally known in the prior art is the use of spirobifluorene-arylamino compounds in OLEDs, including as hole transport materials (WO 2012/034627 and WO 2013/120577).