White light-emitting ZnO:Dy³⁺ nanophosphors: delving into the spectroscopic parameters via Judd-Ofelt analysis

Developing a single-phase white emitting nanophosphor with high quantum efficiency has become a hotspot for scientific world. Herein, single-phase white-light emitting Zn_1-O:xDy³⁺ nanophosphors have been synthesized via a sonochemical method. X-ray diffraction analysis and Raman spectroscopy-based investigations confirmed the hexagonal wurtzite phase for Zn_1-O:xDy³⁺ nanophosphors with preferential growth along the (101) plane. Scanning electron microscopy images showed the formation of a ribbon-shaped morphology with a diameter of ∼25 nm. The emission spectra of the Dy³⁺-activated ZnO nanophosphors exhibited three distinct peaks, namely blue (480 nm), yellow (572 nm), and red (635 nm) emissions, under near-UV excitations related to the ⁴F_9/2 → ⁶H (J = 15/2, 13/2, and 11/2) transitions of Dy³⁺ ions. The values of CIE chromaticity coordinates for the optimized phosphor (x = 0.329, y = 0.334) with correlated color temperature (CCT) of 5657 K indicated cool white-light emission from the phosphor. The thermal stability of ZnO:Dy³⁺ nanophosphors was probed by temperature-dependent luminescence. Quantitative evaluation of Judd-Ofelt intensity parameters, radiative parameters, luminescence decay, and quantum efficiency of Zn_1-O:xDy³⁺ using the J-O theory suggests that these nanophosphors are promising luminescent media for commercial white LEDs and other display devices.