Highly efficient warm white OLEDs based on phenyl group substitution with 2-Phenylpyridine ancillary ligands

Abstract

Stable warm white organic light-emitting diodes (WOLEDs) hold great promise for residential lighting applications. We synthesized three dyes by incorporating trimethylsilyl and phenyl groups with 2-phenylpyridine-based ancillary ligands into Ir(III) complexes, aiming to achieve high-efficiency phosphorescent OLEDs (PhOLEDs) for lighting. The PhOLEDs of the synthesized Ir(III) complexes with (trimethylsilyl)pyridine derivative, acetylacetone (acac) ligand, and 2,2′,6,6′-tetramethylheptanedionate (tmd) ligand exhibits superior de- vice performance compared to commercial Ir(ppy)₃-based PhOLEDs. The green-emissive PhOLEDs with tmd group as the ancillary ligand showed the highest performance, reaching 77.8 cd/A and 69.8 lm/W, surpassing the conventional Ir(ppy)₃ emitter, which achieved 60.2 cd/A and 52.6 lm/W. Notably, white PhOLEDs incorporating the acac group in Ir(III) complexes with (trimethylsilyl)pyridine derivatives produced warm white emission, offering a good color rendering index (CRI) of 86 and stable color, with CIE coordinates of (0.39, 0.43), making them ideal for warm WOLEDs lighting applications.