Hole blocking layer free phosphorescent organic light-emitting diodes by using a charge confining structure

Phosphorescent organic light-emitting diodes without hole blocking layer were developed by using a charge confining device structure which can confine excitons within light-emitting layer. Narrow triplet bandgap host material was sandwiched between wide triplet bandgap host materials and excitons could be effectively confined in narrow bandgap host light-emitting layer. The charge confining devices showed excellent device performances even without hole blocking layer because excitons were confined inside light-emitting layer.