Premium
Synthesis, Structure, Properties, and Application of a Carbazole‐Based Diaza[7]helicene in a Deep‐Blue‐Emitting OLED
Author(s) -
Shi Longqiang,
Liu Zhi,
Dong Guifang,
Duan Lian,
Qiu Yong,
Jia Jiong,
Guo Wei,
Zhao Dan,
Cui Deliang,
Tao Xutang
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200068
Subject(s) - helicene , oled , carbazole , materials science , thermal stability , fluorene , dopant , amorphous solid , photochemistry , molecule , crystallography , optoelectronics , chemistry , nanotechnology , doping , polymer , organic chemistry , layer (electronics) , composite material
Abstract A carbazole‐based diaza[7]helicene, 2,12‐dihexyl‐2,12‐diaza[7]helicene ( 1 ), was synthesized by a photochemical synthesis and its use as a deep‐blue dopant emitter in an organic light‐emitting diode (OLED) was examined. Compound 1 exhibited good solubility and excellent thermal stability with a high decomposition temperature ( T d =372.1 °C) and a high glass‐transition temperature ( T g , up to 203.0 °C). Single‐crystal structural analysis of the crystalline clathrate ( 1 ) 2 ⋅ cyclohexane along with a theoretical investigation revealed a non‐planar‐fused structure of compound 1 , which prevented the close‐packing of molecules in the solid state and kept the molecule in a good amorphous state, which allowed the optimization of the properties of the OLED. A device with a structure of ITO/NPB (50 nm)/CBP:5 % 1 (30 nm)/BCP (20 nm)/Mg:Ag (100 nm)/Ag (50 nm) showed saturated blue light with Commission Internationale de L’Eclairage (CIE) coordinates of (0.15, 0.10); the maximum luminance efficiency and brightness were 0.22 cd A −1 (0.09 Lm W −1 ) and 2365 cd m −2 , respectively. This new class of helicenes, based on carbazole frameworks, not only opens new possibilities for utilizing helicene derivatives in deep‐blue‐emitting OLEDs but may also have potential applications in many other fields, such as molecular recognition and organic nonlinear optical materials.