Narrowband Macrocycles: A New Paradigm for High‐Color‐Purity Organic Light‐Emitting Diodes

Macrocyclic molecules, with their three‐dimensional rigid frameworks and precisely modifiable cavity structures, provide a unique platform for the development of high‐performance organic light‐emitting diodes (OLED) emitters. To meet the stringent demands of ultrahigh‐definition and three‐dimensional displays for narrowband emission and circularly polarized luminescence, three major challenges must be addressed for current multiresonance (MR) narrowband emitters: further spectral narrowing, maintaining high emission efficiency in aggregated states despite their large planar structures, and achieving both narrow full‐width at half‐maximum and high asymmetry factors simultaneously. The introduction of postfunctionalized macrocycles offer a novel solution to this dilemma: their three‐dimensional rigid skeletons act as steric spacers that effectively isolate emissive centers, suppress intermolecular aggregation, and exciton annihilation, thereby preserving narrowband emission while significantly reducing the dependence of device performance on doping concentration. Furthermore, incorporating chiral groups or constructing chiral environments within macrocyclic frameworks can endow narrowband systems with circularly polarized luminescence (CPL) properties, opening new avenues for high‐color‐purity, high‐efficiency circularly polarized OLEDs (CP‐OLEDs), and advanced three‐dimensional displays. Thus, macrocyclic narrowband materials are not only expected to overcome the limitations of conventional small‐molecule narrowband emitters in terms of spectral broadening and aggregation‐induced quenching but also serve as an ideal molecular platform for the integration of chiral optoelectronic functions.