Synthesis of intense red light-emitting β-Ca2SiO4:Eu3+ phosphors for near UV-excited light-emitting diodes utilizing agro-food waste materials

Abstract

The sugarcane baggage ash and chicken shells are the abundant by-products of agro-food waste materials. These waste materials have hazardous impact on environment and thus require proper utilization to get valuable products. The present report is a detailed study to use these materials to fabricate intense red light-emitting Eu-doped Ca2SiO4 (C2S) phosphors via conventional solid-state method. For this purpose, silica (SiO2) is extracted from sugarcane baggage ash at 600 °C via alkali extraction followed by acid precipitation method. The raw eggshells were washed, dried, and calcined in furnace at 900 °C in order to get calcium oxide (CaO). The structural, morphological, elemental, optical, and luminescent properties were characterized via X-ray diffraction, scanning electron microscopy, energy dispersed X-ray spectroscopy, transmission electron microscopy, UV–Visible spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence techniques. The effect of Eu concentration (0.1 to 0.5 mol%) on the structural, optical, and luminescent properties of Ca2SiO4 has been studied in detail. The agro-food waste-derived phosphors exhibited intense emission at 625 nm corresponding to 5D0 → 7F2 transitions of Eu3+ ions under near-UV light excitation at 393 nm. The quenching mechanism and type of energy transfer interactions involved are studied via Blasse and Dexter’s theory. The photometric parameters such as CIE coordinates, CCT values, and color purity are calculated from emission spectra. Judd–Ofelt (Ω2, Ω4) and other spectral parameters (radiative rates, branching ratio, radiative lifetime, and radiative cross-sectional area) are calculated as a probe to investigate the luminescent environment of Eu3+ ions in the Ca2SiO4 host lattice. The present agro-food waste-derived phosphors are expected to be promising candidates for UV-excited white light-emitting diodes in solid-state lightning and optoelectronic devices.