Diverse structures and emission properties of copper(I) iodide complexes based on oxadiazole-type ligand

Abstract

Four new copper(I) iodide complexes with 2-phenyl-5-(4-pyridyl)-1,3,4-oxadiazole (L), namely [Cu2I2L2(PPh3)2]∙2CHCl3 (1∙2CHCl3), [CuIL(PPh3)2]∙MeOH (2), [Cu2I2L4]∙MeCN (3), and [CuIL] (4), were synthesized and characterized by IR, TGA, PXRD, single crystal X-ray diffraction and quantum chemical methods. Triphenylphosphine contained complexes 1 and 2 are highly photoluminescent at room temperature in the solid state (λem = 585 and 523 nm for 1 and 2, respectively), while homoleptic complexes show a moderate emission in similar conditions (λem = 546 and 648 nm for 3 and 4, respectively). In addition, the emission color and/or efficiency were altered by thermal and mechanical stimuli, and the responsiveness was dependent on the complex structure. Efficient solution-processed yellow emitting OLEDs are fabricated based on 1 as dopand. High external quantum efficiency (EQE) of 23 % and maximum current efficiency (CE) of 56 cd/A at the luminance of 1000 cd/m2 are achieved in the obtained device.