Platinum(ii) bis(arylacetylide) complexes bearing diarylamino-substituted bipyridine ligands for solution-processable phosphorescent OLED applications

Abstract

A comprehensive investigation has been carried out on a series of complexes of the type (N^N)Pt(–CC–Ar)₂, where N^N represents diarylamino-substituted 2,2′-bipyridine (bpy) ligands and –CC–Ar refers to the substituted arylacetylide ligands. The introduction of trifluoromethyl and methoxy substituents to the phenylacetylide unit results in color tuning of the phosphorescence energy in these complexes. The bulky diarylamino substituents on the bipyridine ligand showed distinctive electronic properties, resulting in improved hole-transporting characteristics. Solution-processed phosphorescent organic light-emitting devices (PHOLEDs) were fabricated using these Pt^II emissive dopants with poly(9-vinylcarbazole) (PVK) as the host. All the devices exhibit promising performances with the best luminance efficiency being up to 20 cd A⁻¹ and the external quantum efficiency reaching 7%.