Details

Autor(en) / Beteiligte

• Ting, Hao-Chun
• Chen, You-Ming
• You, Hong-Wei
• Hung, Wen-Yi
• Lin, Sheng-Hsun
• Chaskar, Atul
• Chou, Shu-Hua
• Chi, Yun
• Liu, Rai-Hsung
• Wong, Ken-Tsung

Titel

Indolo[3,2-b]carbazole/benzimidazole hybrid bipolar host materials for highly efficient red, yellow, and green phosphorescent organic light emitting diodes

Ist Teil von

• Journal of materials chemistry, 2012-01, Vol.22 (17), p.8399-8407

Erscheinungsjahr

2012

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• By incorporating electron-accepting benzimidazole and electron-donating indolo[3,2-b]carbazole into one molecule, two novel donor-acceptor bipolar host materials, TICCBI and TICNBI, have been synthesized. The photophysical and electrochemical properties of the hybrids can be tuned through the different linkages (C- or N-connectivity) between the electronic donor and acceptor components. The promising physical properties of these two new compounds made them suitable for use as hosts doped with various Ir or Os-based phosphors for realizing highly efficient phosphorescent organic light emitting diodes (PhOLEDs). PhOLEDs using TICCBI and TICNBI as hosts incorporated with Ir-based emitters such as green (PPy) sub(2)Ir(acac), yellow (Bt) sub(2)Ir(acac), and two new red emitters (35dmPh-6Fiq) sub(2)Ir(acac) (i3) and (4tBuPh-6Fiq) sub(2)Ir(acac) (i6) accomplished high external quantum efficiencies ranging from 14 to 16.2%. Nevertheless, the red PhOLED device incorporating TICNBI doped with the red emitter osmium(ii) bis[3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1, 2,4-triazolate]dimethylphenylphosphine [Os(bpftz) sub(2)(PPhMe sub(2)) sub(2)] achieved a maximum external quantum efficiency, current efficiency, and power efficiency of 22%, 28 cd A super(-1), and 22.1 lm W super(-1), respectively, with CIE coordinates of (0.65,0.35). The external quantum efficiency remained high (20%) as the brightness reached to 1000 cd m super(-2), suggesting balanced charge fluxes within the emitting layer, rendering devices with limited efficiency roll-off.