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Study of Configuration Differentia and Highly Efficient, Deep‐Blue, Organic Light‐Emitting Diodes Based on Novel Naphtho[1,2‐ d ]imidazole Derivatives
Author(s) -
Liu Ming,
Li XiangLong,
Chen Dong Cheng,
Xie Zhongzhi,
Cai Xinyi,
Xie Gaozhan,
Liu Kunkun,
Tang Jianxin,
Su ShiJian,
Cao Yong
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201502163
Subject(s) - imidazole , oled , materials science , benzimidazole , optoelectronics , diode , quantum efficiency , electroluminescence , layer (electronics) , photoluminescence , fluorescence , doping , luminescence , light emitting diode , cathode , photochemistry , nanotechnology , optics , chemistry , organic chemistry , physics
Two novel naphtho[1,2‐ d ]imidazole derivatives are developed as deep‐blue, light‐emitting materials for organic light‐emitting diodes (OLEDs). The 1 H ‐naphtho[1,2‐ d ]imidazole based compounds exhibit a significantly superior performance than the 3 H ‐naphtho[1,2‐d]imidazole analogues in the single‐layer devices. This is because they have a much higher capacity for direct electron‐injection from the cathode compared to their isomeric counterparts resulting in a ground‐breaking EQE (external quantum efficiency) of 4.37% and a low turn‐on voltage of 2.7 V, and this is hitherto the best performance for a non‐doped single‐layer fluorescent OLED. Multi‐layer devices consisting of both hole‐ and electron‐transporting layers, result in identically excellent performances with EQE values of 4.12–6.08% and deep‐blue light emission (Commission Internationale de l'Eclairage (CIE) y values of 0.077–0.115) is obtained for both isomers due to the improved carrier injection and confinement within the emissive layer. In addition, they showed a significantly better blue‐color purity than analogous molecules based on benzimidazole or phenanthro[9,10‐ d ]imidazole segments.