Horizontal Orientation of a Linear-Shaped Platinum(II) Complex in Organic Light-Emitting Diodes with a High Light Out-Coupling Efficiency

Abstract

A linear-shaped phosphorescent platinum(II) complex that adopts a horizontal orientation in amorphous films was synthesized. The complex possesses a photoluminescence quantum efficiency of ΦPL = 50±3% in thin films with the host of m-biscarbazolylbenzene and 4,4'-bis(N-carbazolyl)biphenyl. Polarized emission from the edge of these thin films confirmed the horizontal orientation of the complex within them. An organic light-emitting diode containing the complex possessed a maximum external quantum efficiency of ηEQE = 15.8±3%. The light out-coupling efficiency of the device was estimated to be at least Φout = 32±3%, which was ascribed to the horizontal orientation of the complex.