N-coumarin derivatives as hole-transporting emitters for high efficiency solution-processed pure green electroluminescent devices

作者：Kotchapradist Palita; Prachumrak Narid; Sunonnam Thitiya; Tarsang Ruangchai; Namuangruk Supawadee; Sudyoadsuk Taweesak; Keawin Tinnagon; Jungsuttiwong Siri****; Promarak Vinich^*

来源：Dyes and Pigments, 2015, 112: 227-235.

DOI：10.1016/j.dyepig.2014.06.032

• N-coumarin
• Carbazole dendrimer
• Hole-transporting green emitter
• Solution process
• Non-doped emitter
• Organic light-emitting diode

A series of new N-coumarin dyes containing oligothiophenyl N-coumarins as cores and carbazole dendrons up to the third generation as substituents were synthesized and characterized. Their optical, thermal, electrochemical, and electroluminescent properties as non-doped solution-processed hole-transporting light-emitters for electroluminescent devices were investigated. It was found that by incorporating carbazole dendrons in the molecule, we were able to reduce the crystallization and maintain the high emissive ability of a planar N-coumarin fluorescent core in the solid state as well as improve the thermal stability of the material. These N-coumarins showed a bright green fluorescence and could form morphologically stable amorphous thin films with glass-transition temperatures as high as 299 degrees C. Simple structured solution-processed organic light-emitting diodes using these dyes as emissive layers emitted a stable green electroluminescence (lambda(EL) = 517 nm) with high luminance efficiencies (up to 9.45 cd A(-1) at 6.7 mA cm(-2)) and high green color purity.

• 出版日期2015-1