Blue-emitting ionic multi-resonance emitters for efficient narrowband light-emitting electrochemical cells

• • The two ionic MR emitters achieve narrowband blue emission with FWHM of 26–27 nm and PLQYs of 95%–97% in solid-state films, enabling high color purity and efficient radiative recombination for LEC applications. • • LECs fabricated with these emitters exhibit a maximum external quantum efficiency (EQE) of 4.6% and CIE coordinates of (0.12, 0.26), representing the first demonstration of narrowband blue LECs based on intrinsically ionic MR emitters. • • The molecular design covalently bonds an imidazolium group to a B/N-doped polycyclic skeleton, maintaining the MR characteristics while introducing ionic functionality, which is essential for ion migration and p-i-n junction formation in LECs. • • The para-B-π-N linkage between the pyrrolic N and the MR skeleton elevates excited-state energy levels, blue-shifting the emission, while the pyridinic N provides a quaternization site for ionic compatibility, offering a dual-functional strategy for future emitter design.