Small molecule based white organic light-emitting diodes were fabricated by using an alignment free mask patterning method. A phosphorescent red/green emitting layer was patterned by a metal mask without any alignment and a blue phosphorescent emitting layer was commonly deposited on the patterned red/green emitting layer. A white emission could be obtained due to separate emission of red/green and blue emitting layers. A maximum current efficiency of 30.7cd/A and a current efficiency of 26.0cd/A at 1000cd/m 2 were obtained with a color coordinate of (0.39, 0.45). In addition, there was little change of emission spectrum according to luminance because of balanced red/green and blue emissions.