Structural characterization, electronic and photophysical properties of phosphane-based copper(I) complexes and their application to cyan LEDs

Abstract

Two dinuclear Cu(I) complexes, [Cu2(dppe)(dppbz)2I2](1) and [Cu2(dppb)(dppbz)2I2] (2) (dppe = 1, 2-bis(diphenylphosphino)ethane, dppb = 1,4-bis(diphenylphosphino)butane, dppbz = 1,2-bis (diphe nylphosphino)benzene), have been prepared and characterized by IR, TG, XRD, elemental analysis and X-ray crystal structure analysis. Structural analysis indicates that diphosphane ligands connect two Cu atoms to form the S-shape configurations in complexes 1 and 2. DFT calculations demonstrate that the HOMO → LUMO energy gap and Mülliken atomic charges for 1 and 2 are affected by increasing the alkyl chain length of diphosphane ligands, but the composition of HOMOs and LUMOs are hardly changed at the different alkyl chain length of diphosphane ligands. The solid-state luminescent properties of complexes 1 and 2 are observed at 77 K and 298 K, showing that the maximum emission lifetime and quantum yields respectively approach to 6 μs and 26 % at 298 K. Moreover, dinuclear Cu(I) complexes are used to fabricate the cyan light-emitting diodes with the maximum EQE of ca. 20 %.