Enhancement of luminescence intensity and spectroscopic analysis of Eu3+-activated and Li+ charge-compensated CaTiO3 color tunable phosphors for solid-state lighting

Abstract

The present work explores a well-crystallized perovskite calcium titanate (CaTiO3) doped with trivalent europium (Eu3+) and co-doped with lithium ion (Li+) successfully synthesized by a conventional solid-state reaction method, and the impact of single dopant and co-dopant on the photoluminescence performances of the sample has been investigated by emission, excitation and diffuse reflectance spectra at the room temperature. Photoluminescence spectra of Li+-doped CaTiO3:Eu3+ nanophosphor revealed at intense pink emission peak for Ca(0.85−y)Li y TiO3:0.15Eu3+ nanophosphor around wavelength 619 nm in the visible region upon the excitation of near-UV light at wavelength 397 nm due to 5 D 0 → 7 F 2 transition in Eu3+. The incorporation of Li+ ion on CaTiO3:Eu3+ nanophosphors enhanced the emission probability from higher 5 D 0 state to lower 7 F j state, and its PL intensity is found to be three times greater than the intensity of CaTiO3:Eu3+ nanophosphor. The spectral characteristics and the Eu–O ligand behavior were confirmed in light of Judd–Ofelt theory from the Emission spectra rather than absorption spectra. Their crystal structure was confirmed by X-ray diffraction (XRD) which is in good agreement with pure orthorhombic phase with space group Pbnm, and it also indicated that the incorporation of the dopant/co-dopant did not affect the crystal structure. The experimental observation reveals that the developed phosphor material Li+-co-doped CaTiO3:Eu3+ can be used in solid-state lighting devices.