cis‐Quinacridone‐Based Delayed Fluorescence Emitters: Seemingly Old but Renewed Functional Luminogens

Abstract Herein, we report a material design of linear cis ‐quinacridone ( cis ‐QA) derivatives as delayed fluorescence luminogens. In contrast to the widely studied traditional trans ‐isomers, the functionality of cis ‐QA and its derivatives remains unexplored and unclarified. Through combined computational and experimental investigations, we revealed that cis ‐QA derivatives can function as fascinating narrowband deep‐blue delayed fluorescence emitters for organic light‐emitting diodes (OLEDs). The best‐performing deep‐blue OLEDs incorporating these cis ‐QA luminogens achieved high external electroluminescence quantum efficiencies of up to 19.0 % and high color purity with chromaticity coordinates of (0.13, 0.14).