Reddish orange to blue tunable emission from rare earth β-diketonate Eu(TTA)3 dpphen complex for solid state lighting applications

Abstract

This work reports synthesis and characterization of novel Eu(TTA)3 dpphen (Eu-Europium, TTA- 2-Thenoyltrifluoroacetone, dpphen-4,7-diphenyl,1,10-phenanthroline) complex which has potential to tune its emission from reddish-orange to blue colour. Its crystalline nature was revealed by X-ray diffractogram while, the structure formation and molecular bonding of the complex was declared by FTIR spectra. TGA/DTA analysis divulges high thermal stability. UV–visible absorption spectra of the complex in various solvents show two distinct peaks referring to the π → π∗ and n → π∗ optical transitions in the rare earth ions and β-diketonate moieties. Also, various optical transition parameters were evaluated from these results. Under excitation wavelength of 380 nm, the complex in solid state illustrates characteristic reddish-orange light emission registered at 613 nm with narrow full width at half maxima, attributed to f-f transition of central Eu3+ ions. However, solvated complex in various organic solvents such as chloroform, dichloromethane and toluene revealed a red shift by 1 nm with intense sharp emission, peaking at 614 nm. Conversely, solvated complex in acetic and formic acid displays a large blue shift of about 136 and 135 nm, respectively. Various photo physical and photometric properties of the complex reveal its prospective as tunable emissive material that can be coated on flexible substrates for solid state lighting applications. Keywords: Rare earth β-diketonates, Europium, Tunable emission, Photo physical and photometric properties, Organic electroluminescent device, Solid state lighting