Rational Design Strategy for the Realization of Red- to Near-Infrared-Emitting Alkynylgold(III) Complexes and Their Applications in Solution-Processable Organic Light-Emitting Devices

A new class of red- to near-infrared (NIR)-emitting cyclometalated alkynylgold­(III) complexes was designed and synthesized. Red to NIR emission in the alkynylgold­(III) complexes was realized, with the emission band maxima of the complexes in both solution and solid-state thin films found to extend to 823 and 730 nm, respectively. A small energy gap of down to 1.51 eV was achieved in the NIR-emitting complexes, as revealed from the electrochemical studies. Moreover, a large bathochromic shift of ∼1370 cm–1 can be obtained by simply changing the alkynyl ligand. NIR-emitting solution-processable organic light-emitting devices (OLEDs) were also realized, as exemplified by the electroluminescence properties with band maximum at 720 nm and Commission International de L’Éclairage coordinates of (0.67, 0.33) for devices based on complex 1b. This work not only demonstrates a design strategy to extend the emission of gold­(III) complexes into the NIR regime but also represents the first report on gold­(III)-based NIR-emitting OLEDs.