Stable and efficient sky-blue organic light emitting diodes employing a tetradentate platinum complex

A tetradentate Pt(II) complex platinum (II) [10-(9-(4-tert-butylpyridin-2-yl-κN)-9H-carbazol-2-yl-κC1)-9,10-dihydro-9,9-dimethyl-3-(1H-pyrazol-1-yl-κN2)acridine-1-yl-κC1] (PtN′1N-tBu) incorporating pyrazolyl-acridine as the lumophore was demonstrated to act as a stable and efficient sky-blue emitter. Phosphorescent organic light-emitting diode (OLED) employing PtN′1N-tBu without the electron blocking layer (EBL) achieved a high external quantum efficiency (EQE) of 15.9% and an estimated operational lifetime LT70 of 635 h at an initial luminance of 1000 cd/cm2. The device efficiency could be further improved by adding TrisPCz as EBL, reaching EQE of 17.3% and operational lifetime up to 482 h at 1000 cd/cm2.