Enhanced Horizontal Dipole Orientation by Novel Penta‐Helicene Anthracene‐Based Host for Efficient Blue Fluorescent OLEDs
Changchun Kuang, Siqi Li, Imran Murtaza, Zhimin Meng, Hongyang Li, Xinkang Zhang, Chengcheng Wu, Kai‐Ning Tong, Yifan Shang, Yaowu He, Yanan Zhu, Guodan Wei, Hong Meng
Abstract
Abstract Due to the relatively low photoluminescence quantum yield (PLQY) and horizontal dipole orientation of doped films, anthracene‐based fluorescent organic light‐emitting diodes (F‐OLEDs) have faced a great challenge to achieve high external quantum efficiency ( EQE ). Herein, a novel approach is introduced by incorporating penta‐helicene into anthracene, presented as linear‐shaped 3‐(4‐(10‐phenylanthracen‐9‐yl)phenyl)dibenzo[c,g]phenanthrene (BABH) and 3‐(4‐(10‐(naphthalen‐2‐yl)anthracen‐9‐yl)phenyl)dibenzo[c,g]phenanthrene (NABH). These blue hosts exhibit minimal intermolecular overlap of π – π stacking, effectively suppressing excimer formation, which facilitates the effective transfer of singlet energy to the fluorescent dopant for PLQY as high as 90%. Additionally, the as‐obtained two hosts of BABH and NABH have effectively demonstrated major horizontal components transition dipole moments (TDM) and high thermal stability with glass transitional temperature ( T g ) surpassing 188 °C, enhancing the horizontal dipole orientation of their doped films to be 89% and 93%, respectively. The OLEDs based on BABH and NABH exhibit excellent EQE of 10.5% and 12.4% at 462 nm and device lifetime up to 90% of the initial luminance over 4500 h at 100 cd m −2 , which has firmly established them as among the most efficient blue F‐OLEDs based on anthracene to date to the best knowledge. This work provides an instructive strategy to design an effective host for highly efficient and stable F‐OLEDs.