Ambipolar Conductive 2,7-Carbazole Derivatives for Electroluminescent Devices

A series of 2,7‐disubstituted carbazole (2,7‐carb) derivatives incorporating arylamines at the 2 and 7 positions are synthesized via palladium‐catalyzed C–N or C–C bond formation. These compounds possess glass transition temperatures ranging from 87 to 217 °C and exhibit good thermal stabilities, wi...

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Bibliographic Details
Published in:Advanced functional materials 2007-04, Vol.17 (6), p.983-995
Main Authors: Shen, J.-Y., Yang, X.-L., Huang, T.-H., Lin, J. T., Ke, T.-H., Chen, L.-Y., Wu, C.-C., Yeh, M.-C. P.
Format: Article
Language:English
Subjects:
Carbazoles
Electroluminescence
Light-emitting diodes
Light‐emitting diodes, organic
optical
organic
Structure-property relationships
Structure–property relationships, optical
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Summary:A series of 2,7‐disubstituted carbazole (2,7‐carb) derivatives incorporating arylamines at the 2 and 7 positions are synthesized via palladium‐catalyzed C–N or C–C bond formation. These compounds possess glass transition temperatures ranging from 87 to 217 °C and exhibit good thermal stabilities, with thermal decomposition temperatures ranging from 388 to 480 °C. They are fluorescent and emit in the purple‐blue to orange region. Two types of organic light emitting diodes (OLEDs) were constructed from these compounds: (I) indium tin oxide (ITO)/2,7‐carb (40 nm)/1,3,5‐tris(N‐phenylbenzimidazol‐2‐yl)benzene (TPBI, 40 nm)/Mg:Ag; and (II) ITO/2,7‐carb (40 nm)/tris(8‐hydroxyquinoline) aluminum (Alq3, 40 nm)/Mg:Ag. In type I devices, the 2,7‐disubstituted carbazoles function as both hole‐transporting and emitting material. In type II devices, light is emitted from either the 2,7‐disubstituted carbazole layer or Alq3. The devices appear to have a better performance compared to devices fabricated with their 3,6‐disubstituted carbazole congeners. Some of the new compounds exhibit ambipolar conductive behavior, with hole and electron mobilities up to 10–4 cm2 V–1 s–1. Carbazole derivatives incorporating arylamines at the 2 and 7 positions (see figure) are synthesized. Devices that incorporate these light‐emitting materials exhibit ambipolar conducting behavior with good hole and electron mobilities (ca. 10‐4 cm2 V–1 s–1). These materials can be used as hole‐transporting and/or emitting layer in double‐layered electroluminescent devices.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.200600921