Novel β-diketonate complexes of [formula omitted] bearing pyrazole moiety for bright photo- and electroluminescence

Abstract

Four novel 1,3-diketonate Eu3+ complexes bearing pyrazole moieties as main ligands and a 4,7-Diphenyl-1,10-phenanthroline (bathophenanthroline) ancillary ligand were synthesized. The number of fluorine atoms in the main ligand was varied from 3 to 13. From spectroscopic studies of the synthesized complexes we conclude that increasing the degree of fluorination results in a significant rise in the quantum yield and sensitization efficiency. With further extension of the fluorinated chain length, saturation of these characteristics was observed. The maximum obtained values of the quantum yield and sensitization efficiency were 56% and 99%, respectively. In order to reveal the potential of the complexes for OLED applications, electroluminescent devices based on these compounds were fabricated and their performance was studied. It was found that the quantum efficiencies of the OLEDs and the sensitization efficiencies exhibit similar behaviour depending on the degree of fluorination of the ligands in the complexes.