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Organic light-emitting diodes (OLEDs) are energy-efficient; however, the coordinating ligand can affect their stability. Sky-blue phosphorescent Pt(II) compounds with a C^N chelate, fluorinated-<b>dbi</b> (<b>dbi</b> = [1-(2,4-diisopropyldibenzo [b,d]furan-3-yl)-2-phenyl-1<i>H</i>-imidazole]), and acetylactonate (acac) (<b>1</b>)/picolinate (pic) (<b>2</b>) ancillary ligands were synthesized. The molecular structures were characterized using various spectroscopic methods. The Pt(II) Compound <b>Two</b> exhibited a distorted square planar geometry, with several intra- and inter-molecular interactions involving C_π⋯H/C_π⋯C_π stacking. Complex <b>One</b> emitted bright sky-blue light (λ_max = 485 nm) with a moderate photoluminescent quantum efficiency (PLQY) of 0.37 and short decay time (6.1 µs) compared to those of <b>2</b>. Theoretical calculations suggested that the electronic transition of <b>1</b> arose from ligand(C^N)-centered π–π* transitions combined with metal-to-ligand charge-transfer (MLCT), whereas that of <b>2</b> arose from MLCT and ligand(C^N)-to-ligand(pic) charge-transfer (LLCT), with minimal contribution from C^N chelate to the lowest unoccupied molecular orbital (LUMO). Multi-layered phosphorescent OLEDs using One as a dopant and a mixed host, mCBP/CNmCBPCN, were successfully fabricated. At a 10% doping concentration of <b>1</b>, a current efficiency of 13.6 cdA⁻¹ and external quantum efficiency of 8.4% at 100 cdm⁻² were achieved. These results show that the ancillary ligand in phosphorescent Pt(II) complexes must be considered.