Efficient all-solution-processed near-infrared (NIR) polymer light-emitting diode (PLED) based on the [Ir(C^N1)2(C^N2)]-heteroleptic Ir(III)-complex [Ir(iqbt)2(Br-ppy)

Abstract

Despite the potential candidates of NIR emissive cyclometalated Ir(III)-complexes for large-area and scalable NIR-PLEDs, the realization of their all-solution-processed devices with low cost and without sacrifice of satisfactory performance, is much challenging. In this work, using Hiqbt (1-(benzo[b]-thiophen-2-yl)-isoquinoline) as the C^N1 main ligand and Br-Hppy (2-(4-bromophenyl)pyridine) as the C^N2 ancillary ligand, the [Ir(C^N1)2(C^N2)]-heteroleptic complex [Ir(iqbt)2(Br-ppy)] with efficient NIR-phosphorescence (λem = 692 nm; 69% of the λem ≥ 700 nm proportion; τ = 0.48 μs and ΦPL = 0.19) was molecularly designed. Meanwhile, through the doping of the Ir(III)-complex [Ir(iqbt)2(Br-ppy)], its TmPyPB-assisted (TmPyPB = (1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene) multi-layer NIR-PLED-I and all-solution-processed NIR-PLED-II were realized, respectively. Saliently, the attractive performance (ηEQEMax = 3.20% and negligible (ca. 5%) efficiency roll-off) of the NIR-PLED-II, renders [Ir(C^N1)2(C^N2)]-heteroleptic Ir(III)-complexes a new platform to all-solution-processed NIR-PLEDs.