Asymmetric TADF Emitters with 93% Horizontal Dipole Orientation Enable 20.1% EQE in Deep‐Red OLEDs and Spectral Tunability to NIR

ABSTRACT Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) suffer from severe efficiency limitations due to the energy gap law. Herein, we report two NIR TADF emitters, DTN and ATN, engineered with asymmetric, rigid structures and ultrahigh horizontal dipole ratios (93%) to simultaneously achieve high photoluminescence quantum yield. By modulating doping concentrations (1–100 wt.%) in a CBP host, emission wavelengths span 602–770 nm (DTN) and 610–790 nm (ATN). The optimized DTN‐based OLED exhibits an external quantum efficiency of 20.1% at 674 nm—one of the highest values reported for deep red TADF OLEDs based on dicyanopyrazine derivative. Furthermore, devices with other doping ratios also demonstrate superior performance. Even at an emission wavelength of 770 nm, an exceptional EQE of 2.9% is maintained, which ranks among the best for undoped NIR‐OLEDs. This performance stems from the combined effect of the asymmetric design, the rigid structure, and the high horizontal dipole orientation. Our work demonstrates a viable molecular design strategy for high‐efficiency NIR electroluminescence.