Two color white EML is proposed by using blending and spin-coating method through a co-host/dopant system. Device performances were systematically compared based on the optical property of with/without interlayer PVK. When 1-[1,1';3',1'']Terphenyl-5'-yl-6-(10-[1,1 ';3 ',1 ''] terphenyl-5 '-yl-anthracen-9-yl)-pyrene (TP-AP-TP) is a blue emitter with high luminance and external quantum efficiency, NPB is used as a co-host material which has HTL property and wide band gap like a blue emitter. DPAVBi and Rubrene were each used as blue dopant and yellow dopant. Luminance efficiency of the device used interlayer was 4.31cd/A, a value 30% higher than without interlayer (3.31 cd/A) at 10mA/cm(2).