Efficiency improvement of solution processed blue phosphorescent organic light-emitting diodes using an alcohol soluble exciton blocking layer

High efficiency solution processed blue phosphorescent organic light-emitting diodes (PHOLEDs) were developed using a highly polar phosphine oxide exciton blocking material spin coated from an alcohol solution. An orthogonal film could be effectively deposited due to the insolubility of the emitting layer in alcohol solvent, and a multilayer device structure could be fabricated. The quantum efficiency of the solution processed blue PHOLEDs could be improved from 0.1 to 10.5% by using the alcohol soluble exciton blocking layer. The quantum efficiency of the blue PHOLED with spin coated exciton blocking layer was comparable to that of the blue PHOLED with vacuum deposited exciton blocking layer.