Effect of hole injection layer/hole transport layer polymer and device structure on the properties of white OLED.
Copolymers containing carbazole and aromatic amine unit were synthesized by using Pd-catalyzed polycondensation reaction. The polymers were characterized in terms of their molecular weight and thermal stability and their UV and PL properties in solution and film state. The band gap energy of the polymers was also determined by the UV absorption and HOMO energy level data. The polymers had high HOMO energy level of 5.19-5.25 eV and work function close to that of ITO. The polymers were thus tested as hole injection/transport layer in the white organic light emitting diodes (OLED) by using 4,4'-bis(2,2-diphenyl-ethen-1-yl)diphenyl (DPVBi) as blue emitting material and 5,6,11,12-tetraphenylnaphthacene (Rubrene) as orange emitting dopant. The synthesized polymer, poly bis[6-bromo-N-(2-ethylhexyl)-carbazole-3-yl] was found to be useful as hole injection layer/hole transport layer (HIL/HTL) multifunctional material with high luminance efficiency and stable white color coordinate in the wide range of applied voltage.
Cho
Ho Young
HY
Department of Polymer Science, Kyungpook National University, Daegu 702-701, Korea.
Park
Eun Jung
EJ
Kim
Jin-Hoo
JH
Park
Lee Soon
LS