Photophysical properties and OLED applications of phosphorescent platinum(II) Schiff base complexes

Abstract

The syntheses, crystal structures, and detailed investigations of the photophysical properties of phosphorescent platinum(II) Schiff base complexes are presented. All of these complexes exhibit intense absorption bands with λ(max) in the range 417–546 nm, which are assigned to states of metal-to-ligand charge-transfer (¹MLCT) ¹[Pt(5d) ―› π*(Schiff base)] character mixed with ¹[lone pair(phenoxide) ―› π*(imine)] charge-transfer character. The platinum(II) Schiff base complexes are thermally stable, with decomposition temperatures up to 495 °C, and show emission λ(max) at 541–649 nm in acetonitrile, with emission quantum yields up to 0.27. Measurements of the emission decay times in the temperature range from 130 to 1.5 K give total zero-field splitting parameters of the emitting triplet state of 14–28 cm⁻¹. High-performance yellow to red organic light- emitting devices (OLEDs) using these platinum(II) Schiff base complexes have been fabricated with the best efficiency up to 31 cdA⁻¹ and a device lifetime up to 77000 h at 500 cdm⁻².