Near-Infrared Electroluminescence and Low Threshold Amplified Spontaneous Emission above 800 nm from a Thermally Activated Delayed Fluorescent Emitter

Near-infrared (NIR) organic light-emitting devices have aroused increasing interest because of their potential applications such as information-secured displays, photodynamic therapy, and optical telecommunication. While thermally activated delayed fluorescent (TADF) emitters have been used in a variety of high-performance organic light-emitting diodes (OLEDs) emitting in the visible spectral range, efficient NIR TADF materials have been rarely reported. Herein, we designed and synthesized a novel solution-processable NIR TADF dimeric borondifluoride curcuminoid derivative with remarkable photophysical, electroluminescence and amplified spontaneous emission properties. This dye was specifically developed to shift the emission of borondifluoride curcuminoid moiety toward longer wavelengths in the NIR region while keeping a high photoluminescence quantum yield. The most efficient OLED fabricated in this study exhibits a maximum external quantum efficiency of 5.1% for a maximum emission wavelength of 758 nm, which ranks among the highest performance for NIR electroluminescence. In addition, this NIR TADF emitter in doped thin films displays amplified spontaneous emission above 800 nm with a threshold as low as 7.5 μJ/cm², providing evidence that this material is suitable for the realization of high-performance NIR organic semiconductor lasers.