We have fabricated organic white light emitting diodes by mixing two colors from very thin rubrene doped and non-doped DPVBi layers. The device structure was ITO/2-TNATA(15 nm)/${alpha}$-NPD(35 nm)/DPVBi:rubrene(5 nm)/DPVBi(30 nm)/$Alq_{3}(5;nm)$/BCP(5 nm)/LiF(0.5 nm)/Al(150 nm). The yellow-emitting rubrene of 0.7 wt % was doped into the blue-emitting DPVBi host for the white light. CIE coordinate of the device was (0.31, 0.33) at 8 V. The color coordinates were stable at wide ranges of driving voltages. The luminance was over $1,000;cd/m^{2}$ at 8 V and increases to $14,500;cd/m^{2}$ at 12 V. The maximum current efficiency of the device was 8.2 cd/A at $200;cd/m^{2}$.