Enhancement of the power efficiency for p-i-n OLEDs containing organic p-type HAT-CN and n-type LCV materials

Abstract

The p-i-n organic light-emitting devices (OLEDs) with a low turn-on voltage and a high power efficiency were fabricated by organic p-type 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) layer and organic n-type 4,4',4 ''-methylidynetris (N,N-dimethy-laniline) (LCV) materials. The lowest operating voltage of the electron-only devices with a 2.5-wt.% LCV-doped BPhen layer was 4.02 V. The highest values of the current density and the luminance of the p-i-n OLEDs were 429.8 mA/cm(2) at 7.0 V and 10,950 cd/m(2) at 6.8 V, respectively. The turn-on voltage and the power efficiency of the p-i-n OLEDs with a HAT-CN layer and a LCV-doped BPhen ETL were 2.46 V and 2.76 lm/W, respectively. The enhancement of the power efficiency and the decrease in the turn-on voltage of the p-i-n OLEDs were attributed to the improvement of the hole and electron injections due to the utilization of the p-type HAT-CN and the n-type LCV-doped BPhen layers.