A Simple Molecular Design Strategy for Pure‐Red Multiple Resonance Emitters.

Though the flourishment of materials with multiple resonance (MR) in blue to green regions, red‐emissive MR emitters are still rare in literatures, which definitely should be resolved for further applications. Herein, we report a simple molecular design strategy for the construction of pure‐red MR emitters by conjugate charge transfer, which could greatly enhance the π‐conjugation degree and charge‐transfer property of the target molecule while maintaining the basic feature of MR, leading to a significant redshift of more than 128 nm compared to the selected parent MR core. The proof‐of‐concept emitter PPZ‐BN exhibited a pure‐red emission with a dominant peak at 613 nm and a small full‐width‐at‐half‐maximum of 0.16 eV (48 nm). The optimized organic light‐emitting diode showed a high external quantum efficiency of 26.9 %, a small efficiency roll‐off, and an excellent operation stability (LT99) of more than 43 hours at an initial luminance of 10 000 cd m−2. [ABSTRACT FROM AUTHOR]