Unveiling the Centrosymmetric Effect in the Design of Narrowband Fluorescent Emitters: From Single to Double Difluoroboron Cores

Narrowband fluorescent emitters are receiving significant attention due to the great potential for creating ultrahigh-definition organic light-emitting diode displays (UHD-OLED). Unveiling innovative mechanisms to design new high-performance narrowband fluorescent emitters is a concerted endeavor in both academic and industrial circles. Theoretical calculations reveal that the centrosymmetric dianilido-bipyridine boron difluoride framework ( cs -DAPBF 2 ) exhibits significantly reduced structural relaxation compared to previously reported asymmetric structures with monofluoroboron cores, creating new opportunities for the development of narrowband fluorescent emitters. In this work, we present a dual chelation-assisted C–H/C–H homocoupling strategy to efficiently synthesize the 3,3′-amino-2,2′-bipyridine skeleton, enabling the straightforward construction of a series of symmetric cs -DAPBF 2 -based fluorescent emitters. Through molecular optimization, we have developed a high-performance narrowband green fluorescent emitter, cs -DMeAPBF 2 -MP, which demonstrates a narrow full width at half-maximum (fwhm) of 20 nm, a high photoluminescence quantum yield (Φ PL ) of 98%, a large molar absorptivity (ε) of 2.10 × 10 4 M –1 cm –1, and a high horizontal dipole ratio (Θ // ) of 77%. These properties make cs -DMeAPBF 2 -MP a promising candidate for fabricating high-efficiency, narrowband green organic light-emitting diodes (OLEDs) with minimal efficiency roll-off. This study represents the first successful application of the DAPBF 2 architecture in the design of narrowband fluorescent emitters for high-performance OLEDs.