White Light Emission from Thin-Film Samples of ZnO Nanocrystals, Eu3+ and Tb3+ Ions Embedded in an SiO2 Matrix

Abstract

In this work, a method was developed to determine the concentration of Eu3+ and Tb3+ ions in a thin-film sample of SiO2, co-doped with ZnO-nanocrystals (ZnO-nc), to produce a sample of any desired colour in the International Commission on Illumination (CIE) colour space. Using this method, a white light emitting sample was fabricated. The thin-film sample combines red, green and blue emissions from the Eu3+ ions, Tb3+ ions and ZnO-nc, respectively, to create white light or light of any desired colour. The emissions at 614 nm and 545 nm from Eu3+ and Tb3+ ions, respectively, is due to the energy transfer from the excited ZnO-nc to the rare-earth (RE) ions. In this way, only a single excitation wavelength is needed to excite the ZnO-nc, Eu3+ and Tb3+ ions in the sample to produce emission of a desired colour from the sample. We developed an empirical 4th-degree polynomial equation to determine the concentrations of Eu3+ and Tb3+ ions to produce light of any desired colour in the CIE colour space. Based on the above empirical equation, the concentration of Eu3+ and Tb3+ ions for a white light emitting sample was found to be 0.012 and 0.024 molar fractions, respectively. The white light emission from the sample was confirmed by fabricating the sample using the low-cost sol–gel process. The stimulated emission spectra and the experimental emission spectra of the white light sample fit very well. The results presented in this work are important to develop energy efficient solid state lighting devices.

Electrochemical Recovery and Behaviors of Rare Earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) Ions on Ni Sheets

“…To further confirm the oxidation state of Eu elements, photoluminescence spectroscopy was employed for the Eu electrodeposited sample because Eu(III) ion has unique 5 D 0 → 7 F 0,1,2,3,4 transitions in the visible region between 550 and 720 nm [ 37 , 38 , 39 , 40 ], while Eu(II) shows no visible light emission under an excitation of UV light. Figure 7 shows excitation and emission spectra for a thick electrodeposited Eu sample and the corresponding 2D- and 3D-PL contour mapping images.…”

“…The PL intensity of the direct transition to an Eu(III) excited energy level was found to be stronger than that of the indirect transition. Several PL peak positions were commonly observed at 578, 590, 613, 647, and 698 nm, commonly associated to the 5 D 0 → 7 F 0 , 5 D 0 → 7 F 1 , 5 D 0 → 7 F 2 , 5 D 0 → 7 F 3 , and 5 D 0 → 7 F 4 , transitions, respectively [ 37 , 38 , 39 , 40 ]. The 5 D 0 → 7 F 2 transition was observed to be the most intense.…”

Luminescence performance and energy transfer mechanism investigation of RE3+ (Eu3+/Tb3+/Ce3+)-doped Y2O3 phosphors

“…In recent years, rare earth doped luminescent materials have been widely researched and applied in the fields of LED lighting, dynamic display, laser remote sensing, and bioprobes [1][2][3][4][5][6] because of their good luminescence properties, high interference resistance, and high stability. Different kinds of substrates such as oxides, 7 sulfur oxides, 8 fluorides 9,10 and phosphates 11,12 can greatly affect the luminescence performance of the materials, so the matrices have attracted more researchers' attention.…”

Influence of Terbium Doping and Annealing on the Structural and Optical Characteristics of Sputtered Zinc Oxide Thin Films

“…Terbium is one of several RE elements, and Tb 3+ ions exhibit emission bands in the visible spectral range, due to 5 D 4 → 7 F J (J = 3, 4, 5, 6) transitions. ZnO doped with Tb (ZnO:Tb 3+ ) is assumed to be a new type of green phosphor, with interesting photoluminescence (PL) properties [12][13][14]. The co-doping of ZnO with Tb and Eu ions can also be used for the enhancement of the Eu 3+ emission, through the energy transfer from Tb 3+ to Eu 3+ , provided by the spectral overlap of the 5 D 4 → 7 F 6 emission of Tb 3+ , and the 7 F 0 → 5 D 2 absorption of Eu 3+ [14,15].…”