Color-Purity narrow-band near-infrared (NIR) phosphors of [Ir(C^N)2(N^N)]-bis- heteroleptic and [Ir(C^N)(C’^N’)(N^N)]-tris-heteroleptic Ir(III)-complexes forward to high-performance (all)-solution-processed NIR-PLEDs

<title>Abstract</title> <p> The development of high-efficiency color-purity (full-emission beyond 700 nm) near-infrared (NIR)-emitting Ir(III)-complexes toward reliable (all)-solution-processed polymer-matrixed NIR-OLEDs is still a formidable challenge. Herein, a molecular design strategy to asymmetric [Ir(C^N)(C’^N ^’ )(N^N)]- <italic>tris</italic> -heteroleptic Ir(III)-complex (such as [Ir(dpbq)(iqbt)(ftrpz)] ( <bold>Ir-2</bold> ) with one color-responsible <bold>Hdpbq</bold> -HC^N main ligand and one stronger ligand-field strength <bold>Hftrpz</bold> -HN^N ancillary) was successfully adopted. Benefiting from the optimal “trade-off” between efficiency- <italic>l</italic> _em ^Max -FWHM, the [Ir(dpbq)(iqbt)(ftrpz)] ( <bold>Ir-2</bold> ) showed the more efficient color-purity NIR-emission ( <italic>F</italic> _PL = 4.9% (peaking at 758 nm and FWHM of 46 nm)) as compared to [Ir(dpbq) ₂ (ftrpz)] ( <bold>Ir-1</bold> ) counterpart ( <italic>F</italic> _PL = 3.6% (peaking at 786 nm and FWHM of 62 nm)). Accordingly, through non-all-solution-processing, their efficient color-purity NIR-PLEDs ( <italic>h</italic> _EQE ^Max of 2.456% (758 nm) for the <bold>NIR-PLED-2A</bold> <italic>versus</italic> 1.681% (786 nm) for the <bold>NIR-PLED-1A</bold> ) were realized, respectively. And importantly, based on the all-solution-processed device fabrication, the all-solution-processed <bold>NIR-PLED-2B</bold> doped with the <bold>Ir-2</bold> , create a record <italic>h</italic> _EQE ^Max of 2.418% (peaking at 758 nm), engendering the [Ir(C^N)(C’^N’)(N^N)] (such as [Ir(dpbq)(iqbt)(ftrpz)] <bold/> ( <bold>Ir-2</bold> ), etc.) Ir(III)-complexes a platform to efficient and all-solution-processed color-purity NIR-PLEDs. </p>