Thermal and luminescent properties of polymeric acidic organophosphorus complexes of Eu(III) and Tb(III) undoped and doped with 1,10-phenanthroline

Complexes of Eu(III) and Tb(III) with acidic organophosphorus compounds, di(2-ethylhexyl)phosphate (DEHP) and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (EHEP), were prepared and their thermal and luminescent properties were studied. The thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses of the complexes revealed that they are very stable up to 300 °C, and that the thermal decomposition mechanisms of the DEHP and the EHEP complexes differ significantly from each other. To obtain highly efficient luminescence, 1,10-phenanthroline (phen) was introduced as a sensitizer. The element analysis proved that the complex only accommodated phen as a dopant. The photoluminescence (PL) and excitation spectra of Eu(III) and Tb(III) complexes, undoped and doped with phen, are reported. The Eu(III) and Tb(III) complexes excited by UV light produce very bright red and green emissions, respectively, via non-radiative energy transfer from phen to the metals. The quantum yields of the sensitized luminescence of thin films of the complexes are much greater than those of the non-sensitized complexes. The luminescence decay rate was also determined in the powdered state.