Influence of Gd doping on the absolute quantum efficiency and lifetime of EuxGd1−x(TTA)3phens

Absolute quantum yield ( Φ ) is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes Eu x Gd 1− x (TTA) 3 phens are synthesized with the ratio of Gd 3+ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. Eu x Gd 1− x (TTA) 3 phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of Eu x Gd 1− x (TTA) 3 phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the Eu x Gd 1− x (TTA) 3 phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of Eu x Gd 1− x (TTA) 3 phens are of quasi-periodic variation with the change of the Gd 3+ dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the Eu x Gd 1− x (TTA) 3 phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant K r and non-radiative rate constant K nr are calculated. The dependence of K r and K nr on the Gd 3+ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant K r and absolute quantum efficiency have a linear relationship.