TY - JOUR
T1 - Indolo[3,2-b]carbazole/benzimidazole hybrid bipolar host materials for highly efficient red, yellow, and green phosphorescent organic light emitting diodes
AU - Ting, Hao-Chun
AU - Chen, You-Ming
AU - You, Hong-Wei
AU - Hung, Wen-Yi
AU - Lin, Sheng-Hsun
AU - Chaskar, Atul
AU - Chou, Shu-Hua
AU - Chi, Yun
AU - Liu, Rai-Hsung
AU - Wong, Ken-Tsung
PY - 2012/5/7
Y1 - 2012/5/7
N2 - 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)2Ir(acac), yellow (Bt)2Ir(acac), and two new red emitters (35dmPh-6Fiq)2Ir(acac) (i3) and (4tBuPh-6Fiq)2Ir(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)2(PPhMe2)2] achieved a maximum external quantum efficiency, current efficiency, and power efficiency of 22%, 28 cd A-1, and 22.1 lm W-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-2, suggesting balanced charge fluxes within the emitting layer, rendering devices with limited efficiency roll-off.
AB - 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)2Ir(acac), yellow (Bt)2Ir(acac), and two new red emitters (35dmPh-6Fiq)2Ir(acac) (i3) and (4tBuPh-6Fiq)2Ir(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)2(PPhMe2)2] achieved a maximum external quantum efficiency, current efficiency, and power efficiency of 22%, 28 cd A-1, and 22.1 lm W-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-2, suggesting balanced charge fluxes within the emitting layer, rendering devices with limited efficiency roll-off.
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U2 - 10.1039/c2jm30207a
DO - 10.1039/c2jm30207a
M3 - RGC 21 - Publication in refereed journal
SN - 0959-9428
VL - 22
SP - 8399
EP - 8407
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
IS - 17
ER -
