Investigating photoluminescence properties of Eu³⁺ doped CaWO₄ nanoparticles via Bi³⁺ amalgamation for w-LEDs application

Eu³⁺-doped CaWO₄ nanophosphors were synthesised in series for different atomic wt% concentrations (0, 0.5, 1, 2, 5 and 10) of Bi³⁺ by polyol method. Their structure and morphology were characterised using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photoluminescence properties and energy transfer from Bi³⁺ to Eu³⁺ in CaWO₄:Eu³⁺/Bi³⁺ nanophosphors were also investigated. The results revealed that red luminescence of CaWO₄:2Eu³⁺/1Bi³⁺ nanophosphor is 5.4 times stronger than CaWO₄:2Eu³⁺. It was observed that the forces exist between Bi³⁺ and Eu³⁺ are due to the interaction of electric dipole-dipole interactions. The chroma of CaWO₄:2Eu³⁺/1Bi³⁺ nanophosphors was calculated to be 97.40%. The energy transfer process was studied by measuring the decay curves due to Bi³⁺ and Eu³⁺ dopants. Enhanced red emission, high thermal stability, stronger ⁵D₀ → ⁷F₂ absorption intensity, high colour purity and decay studies indicate that CaWO₄:Eu³⁺/Bi³⁺ nanophosphors are potential candidates to be used in white light-emitting diode (wLEDs).