Judd-Ofelt analysis on pH sensitive Eu(tta)3bipy and Eu(dmh)3phen hybrid organic complexes in various organic solvents for solution processed OLEDs

Abstract

Extremely luminescent Eu(tta)3bipy and Eu(dmh)3phen complexes were synthesized by encapsulating the lanthano-ion Eu(III) with β-diketonates ligands (tta: thenoyltrifluoroacetone and dmh: 2,6-dimethyl-3,5-heptanedione) and neutral ligands (bipy: 2,2′ bipyridine and phen: 1,10 phenanthroline) so as to investigate their photo physical parameters in various organic solvents. Various UV-absorbance based transition parameters, Stokes shift and its dependence on solvent polarity were explored by Lippert-Mataga plot. Judd-Ofelt emissive parameters Ω2 and Ω4 (pH: ranging from 6.0 to 8.0) and photoluminescence quantum yield (PLQY) were calculated in different organic solvents. These architechered complexes, when dissolved in different organic solvents maintained their emission in reddish-orange region, irrespective of polarity of solvents. Photometric parameters-CIE coordinates, dominant wavelength, color purity and Color co-related temperature (CCT) were determined. These results reflect their versatility in the manufacture of solution processed electroluminescent devices such as OLEDs, flat panel displays and solid state lighting technology, wherever reddish-orange emission is highly essential. Keywords: Eu(tta)3bipy, Eu(dmh)3phen, PLQY, Judd-ofelt parameters, Solid state lighting technology, Solution processed OLEDs