Organic light-emitting devices with an n-type bis(ethylenedithio)-tetrathiafulvalene-doped 4,7-diphenyl-1,10-phenanthroline electron transport layer operating at low voltage

The electrical and optical properties of organic light-emitting devices (OLEDs) with bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF)-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) electron transport layers (ETLs) were investigated. The current density–voltage characteristics of the OLEDs with BEDT-TTF-doped BPhen ETLs and electron only devices with BEDT-TTF-doped BPhen layers showed that the electrons injected from the cathode were increased by inserting a BEDT-TTF-doped BPhen layer. OLEDs containing BEDT-TTF-doped BPhen layers at a doping concentration of 1 wt.% demonstrated the highest current density and luminance values. Enhancements of the electron injection and luminance as well as a decrease in the operating voltage of the OLEDs were achieved by inserting a BEDT-TTF-doped BPhen layer.