Anomalously Long-Lasting Blue PhOLED Featuring Phenyl-Pyrimidine Cyclometalated Iridium Emitter
Journal
Chem
Journal Volume
3
Journal Issue
3
Pages
461-476
Date Issued
2017
Author(s)
Abstract
Simply replacing pyridine in cyclometalating ligands in FIrpic with pyrimidine affords the complex MS 2, which has a slight red-shifted emission but shorter excited-state lifetime and the capability to form a highly efficient blue phosphorescent organic light-emitting device (OLED) with long operation lifetime (T50 > 2,200 hr). Further replacement of the picolinate-based ancillary ligand of MS 2 with strong-field CF3-containing pyridine-azole ancillary ligands leads to bluer emitters (MS 17 and MS 19) with nearly unitary photoluminescence quantum yield and preferential horizontal emitting dipole orientations (with horizontal dipole ratios of 75%–77%) beneficial for OLED optical out-coupling. OLEDs using MS 17 and MS 19 as emitters gave bluer emission and very high external quantum efficiency exceeding 31% yet with comparably short device lifetimes as FIrpic-based devices. Theoretical analysis indicates that the distinct stability of the MS 2-based device might be attributed to its relatively large energy difference between 3MC (metal center d-d transition) and 3MLCT states.
SDGs
Type
journal article