Luminescent platinum(II) complexes of 1,3-bis(N-alkylbenzimidazol-2'-yl)benzene-type ligands with potential applications in efficient organic light-emitting diodes

Abstract

A series of luminescent platinum(II) complexes of tridentate 1,3-bis(N-alkylbenzimidazol-2'-yl)benzene (bzimb) ligands has been synthesized and characterized. One of the platinum(II) complexes has been structurally characterized by X-ray crystallography. Their electrochemical, electronic absorption and luminescence properties have been investigated. Computational studies have been performed on this class of complexes to elucidate the origin of their photophysical properties. Some of the complexes have been utilized to fabricate organic light-emitting diodes (OLEDs) by either vapor deposition or spin-coating techniques. The chloroplatinum(II) bzimb complexes functionalized at the 5-position of the aryl ring, Pt(R–bzimb)Cl, not only show tunability of emission color but also exhibit high current and external quantum efficiencies in OLED performance. Concentration-dependent dual-emissive behavior in multilayer OLED was observed upon incorporation of pyrenyl ligand to the Pt(bzimb) system. Such devices doped with low concentration of the complex gave rise to white light emission, representing a unique class of small-molecule platinum(II)-based white organic light-emitting diodes.