Synthesis and luminescence characteristics of Na6Ca(1-X)P2O9:X Dy3+ phosphor for outdoor lighting applications

Light emitting devices, especially outdoor lighting light emitting diodes (LEDs) that do not disrupt the natural plant habitat is an interesting field. In this regard, a series of Na6Ca(1-X)P2O9: X Dy3+ (X = 0.02, 0.04, 0.06, 0.08, 0.10) phosphors were synthesized by solid state reaction method. Structural details of the phosphors were analyzed by the X-Ray Diffraction (XRD) analysis. Transmission Electron Microscopy (TEM) analysis proves that the samples are having a one-dimensional needle like morphology which is advantageous for its use in miniaturized devices like LEDs and solar cells. The luminescent properties of Na6CaP2O9:Dy3+ phosphors were investigated via UV–Visible–NIR absorption, photoluminescence excitation and emission spectra and life time analyses. The samples can be well excited by near ultraviolet LED (NUV- LED) chips and exhibit bright, narrow yellow (574 nm) and blue (480 nm) emission respectively corresponding to the 4F9/2 → 6H13/2 and 4F9/2 → 6H15/2 transitions of Dy3+ ions under 350 nm excitation. Since the value of Y/B ratio for the samples being close to unity, they can be a promising candidate for phosphor converted- WLEDs. The temperature dependent PL spectra reveal the thermal stability of the prepared material to be very promising. The average life time values for the optimum concentration sample is 0.0262 ms and is in the submillisecond range indicating their high speed switching response when used in LEDs. The lack of any red-near –IR emission along with the cool appearance of this phosphor proves it as an excellent candidate for outdoor lighting applications. •Highlights (for review).•A new and efficient Dy3+ doped Na6CaP2O9 phosphor was synthesized by solid state reaction method.•The luminescent spectra reveal that the samples can be well excited under near UV light to get an efficient white emission.•The energy transfer interaction between Dy3+ ions was dipole-dipole in nature, as evident from the Dexter theory.•The chromaticity color coordinates of all the samples fall in the vicinity of white region.st.