Efficiency Enhancement of Organic Light-Emitting Devices Fabricated Using a 1,4,5,8,9,11-Hexaazatriphenylene Hexacarbonitrile Silver Electrode

A 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN)/Ag/HAT-CN transparent electrode for organic light-emitting devices (OLEDs) was investigated. The current density of OLEDs was enhanced with an increase in the Ag layer thickness of a HAT-CN/Ag/HAT-CN anode. While the luminance of the OLEDs with a HAT-CN/Ag/HAT-CN anode slightly decreased with increasing thickness of the upper HAT-CN layer, the current efficiency of the OLEDs with thicknesses for the Ag layer of 20 nm and for the upper HAT-CN layer of 100 nm was almost two times higher than that of OLEDs with an ITO anode. Electroluminescence spectra of the OLEDs with a HAT-CN/Ag/HAT-CN anode were shifted due to the micro-cavity effect in the stacked anode, which was confirmed by the transmittance spectra.