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An organic electroluminescent device with a molecularly doped polymer hole transport layer
Author(s) -
Uemura Takashi,
Okuda Nobuyuki,
Kirmura Hiroya,
Okuda Yasuko,
Ueba Yoshinobu,
Shirakawa Tuguru
Publication year - 1997
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199707)8:7<437::aid-pat669>3.0.co;2-s
Subject(s) - materials science , electroluminescence , polymer , doping , crystallization , layer (electronics) , chemical engineering , biphenyl , optoelectronics , composite material , organic chemistry , chemistry , engineering
Electroluminescent(EL) devices have been fabricated using four different polymers with different glass transition temperatures (T g ) dispersed with N,N′‐bis‐(3‐methylphenyl)‐N,N′‐diphenyl‐1,1′‐biphenyl‐4,4′‐diamine (TPD) as a hole transport layer and tris(8‐hydroxyquinoline) aluminum (Alq 3 ) as an emitting layer. It was found that the higher the T g of the polymer, the longer the lifetime of the device. From observations of TPD‐doped polymer films with optical microscope and atomic force microscope, dispersing TPD in the polymers was found to suppress the crystallization that causes the roughness of the film surface. It was also observed that the higher the T g of the host polymers, the more difficult TPD crystallization was. The property of the EL device with polyethersulfone (PES) dispersed with TPD was also investigated. The lifetime of EL device with the TPD doped PES film was improved more than five times at a current density below 10 mA/cm 2 compared with the device with a conventional TPD hole transport layer. © 1997 John Wiley & Sons, Ltd.