Cool white light emission from the yellow and blue emission bands of the Dy(III) complex under UV-excitation

Abstract

A pyrazine as ancillary ligand coordinated to dysprosium(III) tris-acetylacetonate complex was synthesized and thoroughly characterized. Photophysical properties of the Dy(III) complex were investigated both in solution and solid powder. The quantum yield (ɸ) of the complex in chloroform is 0.024. The UV excitation of the complex in the solid state generates white light emission which indicates significant energy transfer from the ligands (acetylacetone and pyrazines) to the Dy(III) ion. This could be due to the appropriate balancing of the intensity ratio of the yellow and blue emission bands of the Dy(III) complex. This represents an example of a single component system. The correlated colour temperature (CCT) of this white light is calculated as 5340.21 K which lies in a cool region. The radiative properties of the Dy(III) complex are calculated using Judd-Ofelt analysis and the phenomenological parameters calculated are Ω2 = 8.07 × 10−20 cm2, Ω4 = 1.94 × 10−20 cm2 and Ω6 = 1.67 × 10−20 cm2. The branching ratio (βR) ratio calculated from the emission spectrum follows the order: 4F9/2 → 6H13/2 > 4F9/2 → 6H15/2 > 4F9/2 → 6H11/2. The βR for the 4F9/2 → 6H13/2 transition is highest, and it contributes 83% to the total emission branching and can be considered as a possible transition for laser amplification. The white light emission from the solid powder Dy(III) complex as a single component may possibly find its use in white light emitting devices (WLEDs).