Solid state white light emitting systems based on CeF3: RE3+ nanoparticles and their composites with polymers

A series of doped CeF3: RE3+ (RE3+: Tb3+, Eu3+ and Dy3+) nanoparticles were synthesized, with the aim of obtaining a white light emitting composition, by a simple polyol route at 160 °C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. Uniformly distributed and highly water-dispersible rectangular nanoparticles (length ∼15–20 nm, breadth ∼5–10 nm) were obtained. The steady state and time resolved luminescence studies confirmed efficient energy transfer from the host to activator ions. Lifetime studies revealed that optimum luminescence is observed for 2.5 mol% Dy3+ and 7.5 mol% Tb3+. The energy transfer efficiencies (Ce3+ to activators) were found to be 89% for CeF3: Tb3+ (7.5 mol%) nanoparticles and 60% for CeF3: Dy3+ (2.5 mol%) nanoparticles. Different concentrations of Tb3+, Eu3+ and Dy3+ were doped to achieve a white light emitting phosphor for UV-based LEDs (light emitting diodes). Finally CeF3, triply doped with 2.0 mol% Tb3+, 4.5 mol% Eu3+ and 3.5 mol% Dy3+, was found to have impressive chromaticity co-ordinates, close to broad day light. The colloidal solutions of doped CeF3 nanoparticles emitted bright green (Tb3+), blue (Dy3+) and white (triply doped) luminescence upon host excitation. Composites of poly methyl methacrylate (PMMA) and poly vinyl alcohol (PVA) were made with CeF3: 5.0 mol% Tb3+, CeF3: 5.0 mol% Dy3+ and triply doped white light emitting composition. The CeF3/PMMA (PVA) nanocomposite films, so obtained, are highly transparent (in the visible spectral range) and exhibit strong photoluminescence upon UV excitation.

Readily dispersible doped cerium fluoride nanoparticles were synthesized. A white light emitting composition could be obtained. Transparent CeF3-poly methyl methacrylate (PMMA) and poly vinyl alcohol (PVA) nanocomposites were obtained, showing potential for solid state lighting devices.Figure optionsDownload high-quality image (162 K)Download as PowerPoint slideResearch highlights
► Readily dispersible doped CeF3 nanoparticles could be synthesized by a low temperature route.
► Detailed lifetime studies depicted efficient energy transfer from host Ce3+ to Tb3+ and Dy3+.
► A white light emitting composition could be achieved by doping suitable amount of Tb3+, Dy3+ and Eu3+.
► Highly transparent nanocomposites of CeF3 with polymers like PMMA and PVA depicted their potential in solid state lighting devices.