Structural,optical, and luminescence properties of Dy3+-activated potassium calcium silicate phosphor for white light-emitting diodes

A dysprosium (Dy³⁺)-activated potassium calcium silicate (K₄CaSi₃O₉) phosphor was prepared using a solid-state synthesis route. The phosphor had a cubic structure with the space group Pa $\overline{3}$ as confirmed using X-ray diffraction (XRD) measurements. Details of surface morphology and elemental composition of the as-synthesized undoped KCS phosphor was obtained using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The chemical structure as well as the vibrational modes present in the as-prepared KCS phosphor was analyzed using Fourier transform infrared (FT-IR) spectroscopy. Diffuse reflectance spectra (DRS) were used to determine the optical bandgap of the phosphors and were found to be in the optical range 3.52–3.71 eV. Photoluminescence (PL) spectra showed intense yellow emission corresponding to the ⁴F_9/2→⁶H_13/2 transition under 350 nm excitation. Commission International de l′Eclairage colour chromaticity coordinates were evaluated using the PL spectral data lie within the white region. Dexter theory and the Inokuti–Hirayama (I–H) model were applied to study the nature of the energy transfer mechanism in the as-prepared phosphors. The relatively high activation energy of the phosphors was evaluated using temperature-dependent PL (TDPL) data and confirmed the high thermal stability of the titled phosphor. The abovementioned results indicated that the as-prepared KCS:Dy³⁺ phosphor was a promising candidate for n-UV-based white light-emitting diodes.