Keiji Okinaka

Substituent effects of iridium complexes for highly efficient red OLEDs

This study reports substituent effects of iridium complexes with 1-phenylisoquinoline ligands. The emission spectra and phosphorescence quantum yields of the complexes differ from that of tris(1-phenylisoquinolinato-C2,N)iridium(iii)(Irpiq) depending on the substituents. The maximum emission peak, quantum yield and lifetime of those complexes ranged from 598-635 nm, 0.17-0.32 and 1.07-2.34 micros, respectively. This indicates the nature of the substituents has a significant influence on the kinetics of the excited-state decay. The substituents attached to phenyl ring have an influence on a stability of the HOMO. Furthermore, those substituents have effect on the contribution to a mixing between 3pi-pi* and (3)MLCT for the lowest excited states. Some of the complexes display the larger quantum yield than Irpiq, which has the quantum yield of 0.22. The organic light emitting diode (OLED) device based on tris [1-(4-fluoro-5-methylphenyl)isoquinolinato-C2,N]iridium(iii)(Ir4F5Mpiq) yielded high external quantum efficiency of 15.5% and a power efficiency of 12.4 lm W(-1) at a luminance of 218 cd m(-2). An emission color of the device was close to an NTSC specification with CIE chromaticity characteristics of (0.66, 0.34).

11.2: Novel Fluorene-Based Blue Emitters for High Performance OLEDs

High performance new blue-emitting host-dopant systems, which consist of pyrene-substituted fluorene hosts such as DPYFL01 and diarylamino-substituted origo(fluorenylene)s represented by BDT3FL as dopants, have been developed. The new host material,DPYFL01 showed high electron-mobility with 1×10−3 cm2/Vs. A device using DPYFL01 demonstrated blue emission (CIE: x, y = 0.15–0.16, 0.20–0.21) with high power efficiency of 4.5 lm/W at 200 cd/m2. The use of 20%BDT3FL inDPYFL01 resulted in deep-blue emission (CIE: 0.15, 0.15) while keeping high power efficiency of 4.6 lm/W at 3.1 V. The device-structure optimization together with the use of an additional host,C-H01 afforded deep-blue emission (CIE: 0.15, 0.14) and higher power efficiency of 4.9 lm/W and external quantum efficiency of 3.9 % at 4.3 mA/cm2 with 200 cd/m2. Lifetime of the optimized device using 10 %BDT3FL was estimated to be over 10,000 hour at an initial luminance of 200 cd/m2.

P‐109: High‐Performable Green‐Emitting OLEDs

High-performance green emitters for OLEDs have been studied. New green emitters, C-GEM1, C-GEM2 and C-GEM3, showed high efficiency and long lifetime when making devices using each material as an emitter. The optimized device demonstrated an external quantum efficiency of over 6% and a power efficiency of 26 lm/W at 1,000 cd/m2 with the lifetime of over 25,000 hours.