Color-purity near-infrared (NIR; λem = 780 nm) and all-solution-processed polymer light-emitting diodes (PLEDs) based on the C1-symmetric [Ir(C^N)2(N^O)]-bis-heteroleptic Ir(III)-complexes

Abstract

Despite concrete efforts to Ir(III)-complex-based NIR-OLEDs/PLEDs, most of them previously reported are not of color-purity NIR-emission, due to the considerable visible-light remnants in the NIR-emissive protocols. Meanwhile, for the limited Ir(III)-complex-based color-purity NIR-OLEDs/PLEDs, it remains a great challenge to realize their high-performance, besides the tackling of non-all-solution-processed operation cost. In this paper, based on the molecular design of [Ir (dpbq)2 (Ln)] (1–2, n = 1–2), the highly conjugated HC^N-main ligand Hdpbq renders its Ir(III)-complexes’ desirable color-purity NIR-phosphorescence (λPL = 780 nm), while electrochemical properties and excited-state dynamics are deeply dependent on the varied N^OH-ancillary ligands with different electronic effects. Especially for the [Ir (dpbq)2 (L2)] (2), its color-purity NIR-phosphorescent high-efficiency (ΦPL = 3.6 %) is arisen from augmented 3MLCT effect and large transition dipole moment (TDM). Importantly, upon its all-solution-processing device fabrication, the first-example of all-solution-processed and color-purity NIR-PLED (λEL = 780 nm; ηEQEMax = 1.4 %), the best of our knowledge, was realized.