Thickness for optimizing of organic layer and multi-layer anode on luminance efficiency in white-light top-emission organic light-emitting diodes.

The multilayer contact structures in both the anode and organic layers for top-emission organic light emitting diodes (TEOLEDs) are studied in this paper. The anode consists of aluminum/gold (Al/Au). The Al is used for high reflectivity and Au for high work function by enhancing the hole injection from the anode into the organic hole injection layer. The organic layer thicknesses on the luminance characteristics were studied. The hole injection (HIL), hole transport (HTL) and electron transport layer (ETL) thicknesses were adjusted to balance the electron and hole recombination ratio. A highest brightness and best luminance efficiency of 8041 cd/m2 and 3 cd/A were obtained, respectively. After optimization of each organic layer thickness, the white top-emission organic light emitting diodes (white TEOLEDs) was also studied. The white TEOLEDs were achieved using two approaches with doped concentrations adjustment (CIE coordinates at x = 0.31, y = 0.38, density of 0.6%) and doped positions adjustment with CIE coordinates at x = 0.30, y = 0.34 at position = 15 nm away from carriers recombination interface.