Emission Of Bi3 Research Articles

Efficient Blue Emission in Organic–Inorganic Metal Halide (TEA)2InCl5 Triggered by Bi3+‐Doping

AbstractLead‐free 0D In‐based organic–inorganic metal halides (OIMHs) have attracted tremendous attention because of their nontoxicity, environmental stability, and excellent photoluminescence properties. However, it remains controversial and unclear whether the luminous division exists in ns2 doping In‐based materials, as the majority of In‐based materials are considered non‐luminous. Herein, a series of Bi3+‐doped (TEA)2InCl5 (TEA = tetraethylammonium) crystals are synthesized and it is determined that the blue emission stemmed from Bi ions. Remarkably, the photoluminescence quantum yield (PLQY) of the blue emission at 469 nm reached 69.69% under 371 nm excitation, exceeding those of previously reported Bi3+‐doped OIMHs. In addition, pristine and Bi3+‐doped compounds exhibited excellent structure and optical stability under humid conditions. This study provides new insights into the photoluminescence properties of In‐based OIMHs, especially regarding the high‐efficiency emission of Bi3+‐doped materials.

Bi3+/Tb3+/Eu3+ triple‐doped Lu2Mg2Al2Si2O12 phosphor for optical temperature sensing and pressure sensing

AbstractThe investigation of multifunctional bright materials is a popular research topic. The first report of the Bi3+, Tb3+, and Eu3+ triple‐doped garnet‐derived structure Lu2Mg2Al2Si2O12 phosphor is presented in this study. The energy transfer system was constructed with unique ultraviolet (UV) emission of Bi3+ ions, which allows phosphor to be used for temperature sensing with self‐calibration capability, Sa = 0.26% (148 K) and 0.56% (98 K), Sr = 0.15% (98 K), and 0.21% (148 K), indicating a high sensitivity in the low‐temperature region. Tb3+ and Eu3+ ions with better thermal stability under 325 nm excitation were chosen to achieve higher pressure sensing performance, the sensitivity was calculated by fluorescence intensity ratio technique and has maximum sensitivities of up to 0.1887 (SPa) and 0.1621 G/Pa (SPr). This provides a new idea for the ensuing design of brand‐new phosphors for optical pressure sensing. This study provides a new perspective on the versatile applications of phosphors.

Optical thermometry based fluorescence intensity ratio in Y2Mg2Al2Si2O12:Bi3+,Eu3+ phosphors

An array of Y2Mg2Al2Si2O12:Bi3+,Eu3+ phosphors were successfully manufactured. The crystal phase, microscopic image and optical properties were systematically surveyed with X-ray diffraction patterns, scanning electron microscopy and fluorescence spectra, respectively. Under 282 nm excitation, for Y2Mg2Al2Si2O12:Bi3+ phosphors, a broadband emission center located at 319 nm was observed, which is derived from the 3P1 → 1S0 transition. For Bi3+/Eu3+ co-doped samples, besides the 319 nm emission of Bi3+, a range of characteristic sharp lines of Eu3+ were observed. Meanwhile, the maximum efficiency of energy transfer (Bi3+ → Eu3+) can arrive to 89.5%. According to the emission spectra at different temperature, the samples present an excellent temperature sensing property based on fluorescence (from Bi3+ and Eu3+) intensity ratio and thermal stability. The maximum relative sensitivity Sr reaches to 0.544 %K−1 at 573 K. The emission intensity at 483 K maintains 95.5% of that at 303 K. All above meaningful results indicate that the samples may have certain application value in the field of temperature measurement.

Tuning luminescence and excellent thermal stability of Gd4.67Si3O13: Bi3+, Eu3+ with energy transfer from Bi3+ to Eu3+

Bi3+ will transfer energy to Eu3+, and the emission can be tuned via adjusting the concentration of Bi3+ and Eu3+. In this work, the luminescence properties of Gd4.67Si3O13: Bi3+, Eu3+ phosphors have been systematically investigated. The emission of Bi3+ is broadband from 400 nm to 600 nm, while that of Eu3+ is sharp lines at the red region. The emission of Gd4.67Si3O13: Bi3+, Eu3+ is tunable from blue to white and red by adjusting the content of Bi3+ and Eu3+ in Gd4.67Si3O13. The broadband of Bi3+ is fitted by Gaussian function, and two different peaks appear, corresponding to BiI and BiII. Also, the Bi3+ ions in Gd4.67Si3O13 transfer energy to Eu3+ ions, demonstrated by using the emission spectrum and the lifetimes. The energy transfer mechanism is dipole-dipole interactions, and the critical energy transition distance (RC) between Bi3+ ions and Eu3+ ions is 14.4 Å. Also, according to the investigating of temperature-dependent emission, the phosphor Gd4.67Si3O13: Bi3+, Eu3+ exhibits good thermal stability because of the luminescence intensity of Gd4.67Si3O13: 0.03Bi3+, 0.09Eu3+ just to 76.5% when the temperature rises to 150 °C. As the temperature is 270 °C, the intensity drops to 43%. CIE chromaticity coordinates of Gd4.67Si3O13: 0.03Bi3+, xEu3+ (x = 0, 0.01, 0.03, 0.05, 0.09, 0.14, 0.16, 0.20 and 0.25) distribute from blue area to white area and that of Gd4.67Si3O13: Eu3+ locates at red area. All results show that Gd4.67Si3O13: Bi3+, Eu3+ phosphors have potential applications under different display requirements.

Synthesis of equal-sized Y2O3:Bi,Eu mono-spheres and their color-tunable photoluminescence and thermal quenching properties

On the basis of the synthesized equal-sized mono-spheres (~ 180 nm), the luminescence properties of Y2O3:0.2 mol%Bi,2xmol%Eu (x = 0.1–7) phosphors were investigated in detail. The PL spectra of Y2O3:Bi,Eu mono-spheres displays both the bluish green/blue emission of Bi3+ at 501/410 nm (3P1-1S0, Bi3+ in C2 or S6 sites) and the red emission of Eu3+ at 612 nm (5D0–7F2) upon 330/375 nm excitation. Increasing the doping concentration of Eu3+ ions in the phosphor mono-spheres significantly enhances Eu3+ emission (5D0–7F2) and reduces Bi3+ emission (3P1-1S0) due to the effective energy transfer from Bi3+ to Eu3+ ions. At the optimal Eu3+ concentration of 3 mol%, the Y2O3:Bi,Eu mono-spheres show an intense red emission and a high external quantum efficiency of 42.8%. The energy transfer (ET) process from Bi3+ to Eu3+ ions is determined to be a resonant type via dipole-quadrupole interaction with an ET efficiency of 86.3%. By varying the Eu3+ concentration, the luminescence color can be tuned from bluish green to nearly white and eventually to orange red under 330 nm excitation (Bi3+ in C2 sites), and also can be tuned from blue to pink and then to orange red under 375 nm excitation (Bi3+ in S6 sites). Temperature-dependent luminescence spectra demonstrated the good thermal stability of the obtained phosphor mono-spheres.

Photoluminescence study of a broad yellow-emitting phosphor K2ZrSi2O7:Bi3+

The photoluminescence of a novel yellow emitting phosphor K2ZrSi2O7:Bi3+ that contains no rare earth ions was investigated. This phosphor was further evaluated as a color converter for white LEDs. The results indicate that K2ZrSi2O7:Bi3+ has strong absorption in 300–400nm region due to the 1S0→3P1 transition of Bi3+. Upon excitation into the 3P1 level of Bi3+, K2ZrSi2O7:Bi3+ gives bright and broad yellow emission (FWHM∼125nm) peaking at 560nm. Except for intensity, the spectral position and shape of the yellow emission band are the same for different concentrations of Bi3+ incorporated K2ZrSi2O7; Both the emission spectra measured at liquid nitrogen temperature (77K) and room temperature have no splitting and they can be well fitted by a single Gaussian profile; time resolved luminescence spectra reveal that the shape of the emission spectra remain unchanged with increasing delay time. These results indicate only one type of Bi3+ center exists in K2ZrSi2O7. Accompanied by a decrease of emission intensity, the emission of Bi3+ is blue-shifted upon heating (λmax=560nm at T=25°C vs. λmax=550nm at T=250°C), which is ascribed to the thermally active phonon-assisted tunneling from the excited states of lower-energy emission band to those of higher- energy emission band. The white light has been reached using K2ZrSi2O7:Bi3+ as a yellow emitting phosphor.

Photoluminescence of BaZrSi3O9:Bi3+ as a yellow emitting phosphor for White LEDs

A yellow-emitting phosphor, BaZrSi3O9:Bi3+, was synthesized in air via solid state reaction method. Luminescence properties of this phosphor were examined by steady-state and time-resolved as well as temperature-dependent luminescence spectra. The obtained BaZrSi3O9:Bi3+ sample shows strong absorption in 300⿿400nm, and gives bright and broad yellow emission centered at 560nm upon 350nm excitation. The broad emission is originated from 3P1⿿1S0 transition of Bi3+, which has a lifetime around ⿼1μs in BaZrSi3O9. Upon heating in the temperature range from room temperature to 250°C, accompanied by the emission intensity deceases (emission intensity at 150°C retains 76% its initial intensity at room temperature), the emission of Bi3+ in BaZrSi3O9 is blue-shifted, which is ascribed to the thermally active phonon-assisted tunneling from the lower energy to the higher energy emission band in the excited states of Bi3+.

Photoluminescence properties of Eu3+ and Bi3+ in YBO3 host under vacuum ultraviolet/ultraviolet excitation

The photoluminescence properties of Bi3+/Eu3+ doped YBO3 phosphors under 147, 168, 185, 222, and 262 nm excitation were studied in this paper. The sensitization luminescence of Eu3+ by Bi3+ was demonstrated and a useful concentration scope, which is 0.05–0.25 mol %, for Bi3+ doped into YBO3:Eu3+ as candidate of plasma display panel red phosphor was optimized. The relative emission intensity of Bi3+ ions occupying C3 sites in YBO3 crystal increases gradually with Bi3+ concentration increasing, while the emission of Bi3+ occupying S6 sites decreases because of energy transfer from S6 sites to C3 sites. The peak of emission band changes from 295 to 320 nm as Bi3+ concentration increases from 0.1 to 0.25 mol %. Therefore, 0.25 mol % is the critical concentration for Bi3+ ions to transfer their absorption energy between different sites at room temperature. As a result, the luminescence of YBO3:Bi3+, Eu3+ decreases as Bi3+ concentration increases further.

Luminescence centers in thin films of yttrium oxide and yttrium-aluminum garnet activated with bismuth

Luminescence spectra and photoluminescence excitation spectra of Y2O3:Bi and Y3Al5O12:Bi thin films were investigated. Luminescence was stimulated by the emission from two types of centers that were associated with the substitution of Bi3+ for Y3+ in sites of the crystal lattice of Y2O3 (Y3Al5O12) with point symmetries C2 and C3i (D2 and C3i). The emission of Bi3+ in the site with point symmetry C3i causes blue luminescence in both Y2O3:Bi and Y3Al5O12:Bi films with maxima at 3.03 eV and 3.15 eV, respectively, that is related to the 3P1-1S0 transition. The emission of Bi3+ in the site with point symmetry C2 gives green luminescence in Y2O3:Bi with the maximum at 2.40 eV that is also related to the 3P1-1S0 transition. The emission of Bi3+ in the site with point symmetry D2 leads to ultraviolet luminescence in Y3Al5O12:Bi with the maximum at 3.75 eV that corresponds to the 3P1-1S0 transition. The red luminescence band with the maximum at 1.85 eV in Y2O3:Bi is due to the presence of structural defects.