OLEDs based on asymmetric heteroleptic Ir(III) emitters

This work presents the synthesis and application of highly efficient heteroleptic Ir(III) complexes for spin-coated OLEDs. By breaking standard molecular symmetry, we developed asymmetric tris-heteroleptic architectures alongside a bis-heteroleptic analog. These fluorinated complexes display outstanding photophysics, with quantum yields approaching unity in solution and maintaining high efficiencies (up to 73%) in solid PMMA matrices, rivaling the commercial FIrpic standard. To translate this intrinsic photoluminescence into practical devices, we fabricated spin-coated OLEDs and evaluated the impact of device architecture. We demonstrate that optimizing charge balance through the addition of PVKc and TPBI layers drastically improves electroluminescence. The engineered architecture boosted the external quantum efficiency (EQE) to 4.0% for the highly asymmetric Ir2 complex. This study highlights the potential of asymmetric Ir(III) emitters and emphasizes the critical role of tailored device engineering in maximizing OLED performance.