Color-tunable circularly polarized electroluminescence from a helical chiral multiple resonance emitter with B-N bonds

Abstract

Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence (CPL) and small full-width at half-maxima (FWHM) are promising multiple resonance (MR) emitters for CP organic light-emitting diodes (CP-OLEDs). This work presents a pair of chiral MR enantiomers, P/M-o[B-N]₂N₂, featuring B-N bonds incorporated within a [7]-helicene skeleton. These enantiomers exhibit narrow 0–0 and 0–1 electronic transition bands, whose relative intensity can be fine-tuned by increasing doping concentrations, resulting in redshifts of the emission peak from 542 to 592 nm. The enantiomers show mirror-symmetric CPL spectra with an asymmetry factor (∣g_PL∣) of 1.0 × 10⁻³. The hyperfluorescent CP-OLEDs with double-sensitized emitting layers display a FWHM of 33 nm, an external quantum efficiency of 25.1%, and a ∣g_EL∣ factor of 7.7 × 10⁻⁴. Notably, the CP-OLEDs realize color-tunable CP electroluminescence peak from 553 to 613 nm by regulating the vibrational coupling. This work provides a novel concept for the design of helical CP-MR materials and CP-OLEDs, highlighting their potential for future applications in advanced optoelectronic devices.