White organic light-emitting devices with a solution-processed small molecular emission layer

A white light-emitting device (WOLED) was fabricated with a solution-processed single emission layer composing a small molecular mixed-host (MH) of N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)-benzidine (NPB) and 4,4′-bis(2,2-diphenylvinyl)-1,1′-bibenyl (DPVBi) by codoping blue dye of 4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl (DPAVBi) and red dye of 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7- tetramethyljulolidyl-9,enyl)-4H-pyran (DCJTB) into the MH. White light emission was realized in an OLED with 1.15 wt.% DCJTB and 4 wt.% DPAVBi doping concentrations. A maximum luminance of 13,638 cd/m ² and a current efficiency of 5.7 cd/A were obtained in the device. These results demonstrate that WOLEDs can be realized through solution-processed small molecular emitting layer, which reduced the cost of devices and avoided the complicated co-evaporation of multiple dopants and host materials in the vacuum deposition.