Efficiency Variations in Organic Light-Emitting Devices Utilizing the 4,4′,4″-tris(N-(2-naphthyl)-Nphenylamino) triphenylamine Hole Transport Layer Doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane

The electrical and the optical properties of organic light emitting devices (OLEDs) with a 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ) doped 4,4′,4″-tris(N-(2-naphthyl)-Nphenylamino)triphenylamine (2-TNATA) hole transport layer (HTL) were investigated. In comparison with that of the OLEDs containing an undoped 2-TNATA layer, the hole transport efficiency of OLEDs with a F4-TCNQ doped 2-TNATA HTL was significantly enhanced due to an increase in the doping concentration and resulted in enhancement of the luminance. The electroluminescence spectra for the OLEDs with a doped HTL showed a dominant emission peak corresponding to the Alq3 layer. This peak was not affected by the existence of the F4-TCNQ doped HTL.