Intramolecular hydrogen bond enables ultranarrowband multiple resonance luminescence with refined emission profiles

Ultrahigh-definition displays urgently demand narrowband emitters with ideal Gaussian emission profiles. Multiple resonance (MR) systems are highly competitive yet face a formidable bottleneck: The minimum achievable emission linewidth has become an elusive threshold that cannot be further broken for existing systems. Here, the study proposes a pioneering strategy via intramolecular hydrogen bond construction to break the spectral limit of indolocarbazole (ICz) emitters and develops rotary chiral ICz-fused enantiomeric isomers. This chirality-modified ICz emitter concurrently achieves an emissive peak of 466 nanometers, a full width at half maximum (FWHM) of 56 milli-electron volts, and a suppressed shoulder peak in dilute toluene, impressively achieving the narrowest emission among all reported circularly polarized MR emitters to date. The corresponding electroluminescence device exhibits ultrapure deep-blue emission with a peak wavelength of 469 nanometers and an FWHM of 15 nanometers, as well as high maximum external quantum efficiency of 32.5% with minimal roll-off (20.6% at 10,000 candelas per square meter).