Dual‐Multiple Resonances Groups Construct Through‐Space Charge‐Transfer Narrowband Electroluminescent Emitters

Abstract A simple and efficient strategy is developed to effectively reduce the emission spectral width of through‐space charge‐transfer (TSCT) electroluminescent (EL) emitters by incorporating dual multiple resonance (dual‐MR) groups into a single molecule and utilizing a spatially hindered connection approach. Based on this design principle, three proof‐of‐concept EL emitters, m ‐CzFBN, o ‐NOFBN, and o ‐CzFBN is successfully developed, featuring a rigid molecular backbone and TSCT characteristics. Unlike conventional TSCT molecules, which exhibit broad emission spectra and large full‐width at half‐maximum (FWHM) values, the newly designed molecules demonstrate significantly narrow full‐width at half‐maximum (FWHM) values. Notably, m ‐CzFBN displays an emission bandwidth as narrow as 15 nm in solution, representing the narrowest spectral width reported to date for any TSCT emitter. Moreover, all three emitters exhibit high photoluminescence quantum yields (PLQYs) exceeding 90%, which directly enhances their EL performance. A non‐sensitized organic light‐emitting diode (OLED) fabricated using m ‐CzFBN achieved an external quantum efficiency (EQE) of up to 34.0%, ranking among the highest efficiencies reported for narrow‐band TSCT emitters. These findings provide a promising molecular design strategy for developing narrowband EL emitters suitable for ultra‐high‐definition (UHD) display applications.