A Rigid and Strong Donor Strategy for Solution‐Processed Neat‐Film Near‐Infrared OLEDs Beyond 900 nm

Abstract

ABSTRACT Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) generally suffer from low external quantum efficiencies (EQEs). Conventional NIR thermally activated delayed fluorescence (TADF) emitters predominantly rely on triphenylamine (TPA)‐based donors, restricting further molecular design. Herein, we develop four new NIR‐TADF emitters incorporating a rigid and strongly electron‐donating donor unit, in which the charge‐transfer characteristics are finely tuned by regulating the connection positions of cyano groups on the acceptor framework. Solution‐processed neat‐film OLEDs exhibit electroluminescence from 867 to 922 nm. Notably, the device based on tBPz‐CN36 achieves an EQE of 0.01% at 922 nm, representing one of the highest values reported for neat‐film NIR TADF OLEDs in this spectral region. This work demonstrates that the introduction of a rigid donor that is independent of the TPA system, together with acceptor‐site engineering through regulation of cyano connection positions, provides an effective molecular strategy for achieving long‐wavelength NIR TADF emission beyond conventional TPA architectures.