Constructing Highly Efficient Blue OLEDs with External Quantum Efficiencies up to 7.5 % Based on Anthracene Derivatives.

Acquiring desirable device performance with deep‐blue color purity that fulfills practical application requirements is still a challenge. Bipolar fluorescent emitters with hybrid local and charge transfer (HLCT) state may serve to address this issue. Herein, by inserting anthracene core in the deep‐blue building blocks, the authors successfully developed two highly twisted D‐π‐A fluorescent emitters, ICz‐An‐PPI and IP‐An‐PPI, featuring different acceptor groups. Both exhibited superb thermal stabilities, high photo luminescent quantum yields and excellent bipolar transport capabilities. The non‐doped OLEDs using ICz‐An‐PPI and IP‐An‐PPI as the emitting layers showed efficient blue emission with an external quantum efficiency (EQEmax) of 4.32 % and 5.41 %, and the CIE coordinates of (0.147, 0.180) and (0.149, 0.150), respectively. In addition, the deep blue doped device based on ICz‐An‐PPI was achieved with an excellent CEmax of 5.83 cd A−1, EQEmax of 4.6 % and the CIE coordinate of (0.148, 0.078), which is extremely close to the National Television Standards Committee (NTSC) standard. Particularly, IP‐An‐PPI‐based doped device had better performance, with an EQEmax of 7.51 % and the CIE coordinate of (0.150, 0.118), which was very impressive among the recently reported deep‐blue OLEDs with the CIEy <0.12. Such high performance may be attributed to the hot exciton HLCT mechanism via T7 to S2. Our work may provide a new approach for designing high‐efficiency deep‐blue materials. [ABSTRACT FROM AUTHOR]