Naphthyridine‐Based Donor–Acceptor Boron Difluoride Complexes Targeting Red Emission in Organic Light‐Emitting Diodes

ABSTRACT Four donor–acceptor boron difluoride complexes 1–4 based on triphenylamine electron donor and [1,3,5,2]oxadiazaborinino[3,4‐ a ][1,8]naphthyridine acceptor are synthesized and systematically investigated as emissive and charge‐transport materials for organic optoelectronics. Comprehensive spectroscopic and electrochemical studies reveal a pronounced intramolecular charge transfer character of these compounds, leading to solvent‐polarity‐dependent photophysical properties such as bathochromically shifted emission spectra. Charge‐carrier mobility measurements demonstrate balanced hole and electron transport properties, highlighting the potential of these materials for optoelectronic applications. In the solid state, compounds 1 and 2 exhibit near‐unity photoluminescence quantum yields (PLQY) in polymethylmethacrylate and 1,3‐bis( N ‐carbazolyl)benzene matrices, whereas the CF 3 ‐substituted analogues 3 and 4 show markedly red‐shifted emission accompanied by reduced PLQYs. The dyes are successfully employed as emitters in organic light‐emitting diodes (OLEDs) using doping‐free, host‐containing, and interface exciplex‐forming architectures, as well as multiple ultrathin emissive layer configurations, exhibiting an external quantum efficiency of up to 12.76% in the best case. Furthermore, compounds 3 and 4 enable the fabrication of far‐red OLEDs with triple ultrathin emissive layer configurations, exhibiting electroluminescence maxima at 650 and 688 nm, respectively. These results establish donor–acceptor boron difluoride complexes as promising platforms for color‐tunable emission and diverse OLED device architectures.