Configuration Effects of Exciton Blocking Layer with Low Electron Mobility's Electron Transport Layer in Blue Phosphorescent Organic Light-Emitting Diodes

The structural change with the different location of exciton blocking layer's (EBL) in blue phosphorescent organic light-emitting diodes (PHOLEDs) were investigated, where N, N'-dicarbazolyl-3,5-benzene (mCP) with high triplet bandgap was used as the EBL. The change of recombination zone (RZ) were originated from the different formation of triplet excitons depending on the EBL location between hole/electron transporting layer (HTL/ETL) and emission layer (EML), resulting in the variation of the device performance and generating an optical micro-cavity effect in the electroluminescence (EL) spectrum around 500 nm. The device using the EBL between the HTL and the EML showed the highest device performance due to the good charge balance, avoiding the serious triplet exciton quenching and the reduced micro-cavity effect. (C) 2015 The Electrochemical Society. All rights reserved.