Photoluminescence Excitation Spectra Research Articles

Assessing the Determinants of Cavity Polariton Relaxation Using Angle-Resolved Photoluminescence Excitation Spectroscopy.

The strong coupling of light and matter within electromagnetic resonators leads to the formation of cavity polaritons whose hybrid nature may help certain ground and excited state chemical processes. To help enable the development of polariton chemistry, we have developed and applied a spectroscopic technique to leverage the relatively larger spatial coherence of polaritons to assess the determinants of relaxation in hybrid light-matter states. By exciting the lower polariton (LP) state in cavity samples filled with different metalloporphyrin chromophores, we measured and modeled angle-resolved photoluminescence excitation spectra. Our results suggest that the shortest lived constituent of the LP state characterized by specific Hopfield coefficients limits the light absorption of the intracavity molecules, which we equate with the effective polariton lifetime. Our results suggest that researchers need to consider the lifetimes of both photons and excitons participating in strong light-matter coupling when designing polaritonic systems and the methods they can use to assess the relaxation of polaritonic states.

Effect of different BaO contents on the photoluminescence properties of the Eu2+-doped high thermal stability Sr3−xBaxMgSi2O8 phosphors

In this study, 0.015 Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 ([Formula: see text], 0.3, 0.6, 0.9) were used as compositions to find the effect of BaO content on their photoluminescence excitation (PLE) and photoluminescence emission (PL) properties. They were sintered at 1400°C in a reduction atmosphere of 95% N[Formula: see text]% H2 to form blue phosphors. X-ray diffraction pattern and SEM observation were used to analyze their crystal properties, and a fluorescence spectrophotometer was used to analyze their PLE and PL properties. After conducting a thorough analysis, our research primarily encompasses four significant research themes. First, SEM observations revealed that synthesized Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors exhibit the formation of whisker-like structures. Therefore, the whisker-like structures in all the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors were analyzed using the HRTEM and its equipped EDS to find how BaO content influenced both the quantity and fineness of these whiskers. Second, we examined the impact of BaO content on the PLE and PL emission intensities of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors across a temperature range from room temperature to 210°C. This investigation aimed to uncover the effects of BaO content and temperature on the thermal stability of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors. Lastly, our fourth important investigation involved reorganizing the PLE spectra of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors with the energy band as the x-axis. The Gaussian fitting function was applied to analyze the excitation spectra and discern the influence of BaO content on the value of the Stokes shift.

Integrating K+ into Eu and Tb doped GdCa4O(BO3)3: A dual study on photoluminescence and structure

In this study, we investigate the structural and photoluminescence (PL) properties of rare-earth-doped GdCa4O(BO3)3 (GdCOB) phosphors, specifically focusing on the spectral behaviour induced by doping with Eu³⁺ and Tb³⁺ ions. The powder X-ray diffraction (XRD) spectra confirm the formation of a monoclinic phase. The XRD data were also refined by a Rietveld refinement method. The existence of B, O, Ca, Gd, Tb, Eu and K elements was verified by EDS spectra. We introduce a detailed examination of the charge compensation process using Kröger-Vink notation to clarify the mechanisms essential for tailoring the optical properties of the phosphors. The PL excitation spectrum of GdCOB:Eu3+, monitored at 611 nm, reveals sharp excitation peaks at 319, 361, 380, and 392 nm, corresponding to 7F0→5H3, 7F0→5D4, 7F0→7F0, and 7F0→5L6 transitions, respectively. The PL spectrum under excitation of 392 nm exhibits that phosphors doped with Eu3+ a significant red emission at 611 nm, which is attributed to the 5D₀→7F₂ transition. This emission intensity is particularly enhanced at non-centrosymmetric sites of the Eu³⁺ ions. Similarly, the PL excitation spectrum of GdCOB:Tb3+, monitored at 552 nm, displays distinct excitation peaks at 316, 341, 353, and 379 nm, which correspond to the transitions 7F₆→5D₀, 7 F₆→5L₇, 7F₆→5D₂, and 7F₆→5D₃, respectively. Tb³⁺-doped phosphors display a bright green emission, with a dominant peak at 552 nm, resulting from the 5D₄→7F₅ transition. Additionally, the introduction of K⁺ ions as co-dopants results in modifications to the local environments of Eu³⁺ and Tb³⁺ ions. These changes allow for fine-tuning of the emission peaks, significantly enhancing the luminescent output of the phosphors. Optimal doping concentrations of 5 mol% for Eu³⁺ and 1 mol% for Tb³⁺ enhance luminescent intensity and prevent concentration quenching. This phenomenon, often resulting in reduced PL intensity at higher dopant levels, is primarily due to dipole-dipole interactions, consistent with Dexter's theory of energy transfer. Strategic modulation of doping concentrations, coupled with a deep understanding of energy transfer mechanisms are critical for the development of advanced luminescent materials Our analysis of the Commission de l′Eclairage (CIE) chromaticity coordinates reveals enhanced energy transfer dynamics in rare-earth-doped borates, facilitating the tuning of luminescent properties. These results not only deepen our understanding of the fundamental physics governing such phosphors but also open pathways for the development of optoelectronic applications requiring consistent color output, such as LED technologies and solid-state lighting.

Luminescent properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, and Ba)

We investigated the luminescence properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, or Ba) phosphors synthesized using the coprecipitation method. Structural analysis of the phosphors was performed using X-ray diffraction patterns, which revealed that the prepared samples exhibited a pure phase with diffraction peaks matching those of undoped orthorhombic structures. The luminescence properties of the phosphors were examined by measuring photoluminescence and photoluminescence excitation spectra. We found that both Eu2+ and Eu3+ emissions were detected for A = Ba and Ca, whereas only Eu2+ emission was observed for A = Sr. Further, time-resolved photoluminescence decay curves indicate the presence of Eu2+ and Eu3+ luminescence with different lifetimes. The optically stimulated luminescence (OSL) and thermoluminescence (TL) responses of the samples were investigated. The OSL and TL responses were found to vary linearly with the irradiation dose. This study sheds light on the potential applications of Eu-ion-doped ASO4 phosphors in radiation dosimetry and optoelectronic devices.

Luminescence studies and Judd Ofelt parameterization of Dy3+ activated La2(WO4)3 yellow phosphor

The synthesis and detailed luminescence studies of a series of La2-xDyx(WO4)3 (x = 0.02, 0.1, 0.2, 0.4, 0.6, 0.8) phosphors synthesized via microwave-assisted co-precipitation technique is reported in this paper. The XRD analysis confirmed that the phosphors were crystalized in a monoclinic structure with space group C2/c and FTIR analysis identified the characteristic vibrational modes. Morphological studies were conducted using FESEM analysis, and the EDS technique substantiated the effective incorporation of Dy3+ ions in La2(WO4)3. The photoluminescence excitation and emission spectra of varying concentrations of Dy3+ ions were recorded and an optimum concentration of 10 % exhibited the highest intensity. The emission spectra of all phosphors were dominated by peaks at 484 nm and 574 nm. The radiative properties were evaluated using Judd-Ofelt analysis and the JO intensity parameters followed the trend Ω2 > Ω6 > Ω4. The gradual decrease in the decay lifetime value of 4F9/2 excited level with an increase in doping concentration elucidates concentration quenching phenomena due to dipole – quadrupole interaction. The emission data were also analyzed by calculating CIE coordinates and concluded that Dy3+ doped La2(WO4)3 phosphors have potential applications in yellow light generation.

Effect of gamma-irradiation on the photoluminescence of silver-doped lithium triborate glass.

Optical-luminescence properties, including absorption spectra, photoluminescence excitation spectra, and changes in photoluminescence spectra after irradiation with γ-rays in the dose range of 1-3Gy, were measured for novel L i B 3 O 5:A g dosimeter glass. A clear dependence of the intensity of the photoluminescence (PL), with a maximum of approximately 300nm, on the dose value when excited by light with λ e x c =220n m was observed. The mechanism of PL in γ-irradiated L i B 3 O 5:A g glass is proposed to be a consequence of radiation annihilation with the emission of relaxed exciton-like electronic excitations with the participation of impurity defects (A g 0) in the glass structure. Considering that L i B 3 O 5 has an effective atomic number of Z e f f =7.39, which is the closest to Z e f f =7.42 of human body tissue, L i B 3 O 5:A g glass can be very promising for γ-dosimetry in medical practice during radiation therapy of patients with cancer. The presence of lithium Li(6) and boron B(10) isotopes increases the sensitivity of L i B 3 O 5:A g glass to neutrons, which is promising for the manufacture of individual neutron dosimeters for applications in a new field of radiation therapy-neutron therapy.

Luminescence of some lanthanides in synthetic yttrium gagarinite (NaCaYF6)

NaCaYF6 is the formula for gagarinite. Noting the lack of luminescence studies in this material, we synthesized it using the hydrothermal method and investigated the luminescence of several lanthanides. Characteristic luminescence of Eu[Formula: see text], Dy[Formula: see text], Sm[Formula: see text] and Tb[Formula: see text] was observed. Detailed results on photoluminescence emission and excitation spectra, lifetime, chromaticity coordinates and concentration dependence of emission intensity are presented. Except for Tb[Formula: see text], which exhibits f-d excitation, the luminescence of other activators got quenched at 1[Formula: see text]mol % concentration. Eu[Formula: see text] emission in this host was peculiar, in that the emissions from higher 5D states were observed. Luminescence characteristics are explained using the known energy level diagrams for the lanthanide activators.

Effect of annealing temperature and doping concentrations on structure and optical properties of Eu3+-doped TiO2 nanomaterials

In this study, we successfully synthesized europium-doped TiO2 (TiO2:Eu3+) nanomaterials (NMs) with crystalline sizes ranging from 6.5 to 71.7 nm through a sol-gel method. Analysis of X-ray diffraction (XRD) patterns and ultraviolet-visible (UV-Vis) spectra indicates that the substitution of smaller-sized Ti4+ ions (0.745 Å) by larger-sized Eu3+ ions (0.947 Å) was more efficient at higher doping concentrations and annealing temperatures. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the synthesized TiO2:7%Eu3+NMs exhibit a strong red emission band peaking at 613 nm and remarkable absorption in the blue light region centered at 463 nm, making them suitable for use in white light-emitting diode (WLED) applications. Our findings reveal that both annealing temperature and doping concentration significantly influence the structure and properties of these materials. Besides, the research team has seen, under the experimental conditions, the TiO2:7%Eu3+ sample annealed at 800°C exhibits the highest PL intensity. These results underscore the potential of the synthesized TiO2:Eu3+ NMs as red-emitting materials for WLED applications.

Zero-thermal-quenching broadband yellow-emitting Bi3+-activated phosphors based on metal to metal charge transfer

Bi3+-activated phosphors have been proven to have potential applications foreground in white light-emitting diodes (WLED), plant growth lamps and temperature sensing. Therefore, it is urgent to exploit high-efficiency Bi3+-activated phosphors. Herein, a novel broadband yellow-emitting phosphor Ba2GdGaO5:Bi3+ with high internal quantum efficiency (IQE = 77%) was obtained based on metal to metal charge transfer (MMCT) between Bi3+ ground state and Gd3+ excited states. The photoluminescence excitation (PLE) spectrum and photoluminescence (PL) spectrum range from 225 nm to 400 nm and 400 nm to 700 nm, respectively, which can avoid the reabsorption phenomenon efficiently. Besides, Ba2GdGaO5:Bi3+ has superior thermal stability and it shows zero-thermal-quenching at 150 °C. The K+ doping hardly changes the thermal stability and can improve the PL intensity to 133.1% when the K+ concentration is 2%. Finally, a phosphor-convert WLED (pc-WLED) was simply synthesized by Ba2GdGaO5:Bi3+ and BaMgAl10O17:Eu2+ (BAM:Eu2+) phosphors. The doping of Eu3+ can significantly enhance the color rendering index (CRI, from 88.1 to 91.5) and reduce the correlated color temperature (CCT, from 4911 K to 4014 K). The above experimental results demonstrated that the phosphor has great application prospect in WLED.

Comparative study on fluorescence intensity ratio and chromatic coordinate temperature measurement using CsPbBr3-Eu3+ co-doped glass

We have fabricated CsPbBr3-Eu3+ co-doped glass for optical temperature measurement. Photoluminescence (PL) spectra, PL excitation (PLE) spectra and PL decay have been measured. The CsPbBr3 and Eu3+ show distinguishable PL spectra and different temperature dependences. Fluorescence intensity ratio (FIR) and chromatic coordinate temperature measurements are investigated. Absolute sensitivity (Sa), relative sensitivity (Sr) and temperature measurement accuracy (UT) are analyzed. For the FIR method, the Sa and Sr are better in comparison with other temperature sensing materials. The chromatic coordinate is calculated by using PL spectra. Comparing with FIR method, the chromatic coordinate method has smaller Sa and Sr, but better UT due to small uncertainty Ur(x). In addition, the chromatic coordinate method has linear temperature dependence, good compatibility and universality. Both FIR mode and chromatic coordinate mode have excellent temperature cycle characteristics..

Visible room-temperature emission and excitation photoluminescence in In+- and As+-co-implanted SiO2 films

The visible room-temperature emission and excitation photoluminescence spectra were studied as a function of the indium and arsenic profiles in the In+ and As+ ion-implanted thermally grown SiO2 films before and after the annealing at the temperature of 900 °C. As+ ions at the energy of 40 or 135 keV and In+ ions at the energy of 50 keV, providing a projective range ratio RpAs/RpIn of 1 or 3, respectively, were used. Four emission photoluminescence bands, peaked at ∼347 nm (3.57 eV), ∼440 nm (2.81 eV), ∼450 nm (2.75 eV) and ∼500 nm (2.48 eV), were obtained from the 40 keV As+ and 50 keV In+ ion-implanted samples under the excitation wavelength of 300 nm (4.13 eV), 350 nm (3.54 eV), 400 nm (3.10 eV) and 450 nm (2.75 eV), respectively. As the As+ energy increased to 135 keV, under the same excitation conditions, the emission bands peaked at 370 nm (3.35 eV), 420 nm (2.95 eV), 460 nm (2.69 eV) and 505 nm (2.45 eV) dominated in the photoluminescence spectra. The excitation spectra of the observed emission peaks were studied, too. We preliminarily interpret the observed photoluminescence peaks as a result of the T1 → S0 transition of molecular-like clusters associated with the oxygen deficiency provided by In or In–As in ion-implanted SiO2.

Superior Quantum Efficiency Blue‐Emitting Phosphors with High Thermal Stability toward Multipurpose LED Applications

AbstractSince Bi3+‐activated phosphor are widely reported in phosphors‐converted light‐emitting diodes (pc‐LEDs), developing new‐high efficiency phosphors is imperative. Herein, superior internal quantum efficiency (IQE = 93.7%) and external quantum efficiency (EQE = 70.5%) are achieved with blue‐emitting gallate phosphor CaGdGaO4:Bi3+. Particularly, the photoluminescence excitation (PLE) spectrum ranges from 200 to 400 nm with two peaks at 337 and 368 nm, which match well with the 365 nm near ultraviolet (n‐UV) chip. The blue emission is attributed to two luminescence centers caused by Bi3+ occupying GdO6 and CaO6 sites. Furthermore, the thermal stability (@ 150 °C) enhanced from 73.2% to 80.1% when Ca2+ doping. A white LED (WLED) with high color rendering index (Ra) of 93.8 is prepared by as‐synthesized phosphors, indicating the potential application in WLED. The blue and red dual‐emitting phosphors are achieved by co‐doping Bi3+ and Eu3+. Finally, the rice planting experiment presents that the blue‐emitting can efficiently enhance the photosynthesis and seeding index of rice, which indicated these phosphors have significance in plant fill light.

Synthesis, characterization and optical tuning of Sm3+ doped NaZnPO4 phosphors for white LED technology

This study presents a comprehensive investigation into the synthesis, structural-spectroscopic characterization, and optical properties analysis of Sm3-activated NaZnPO4 phosphors with varied Sm3+-doping percentiles, aimed at developing tunable luminescent materials for white-light-emitting diode (WLED) applications. The polycrystalline samples NaZn(1-x) Smx3+ PO4 (x = 0.00, 0.05, 0.10 and 0.15) phosphors were synthesized via a solid-state reaction method. X-ray diffraction data analysis confirms single phase monoclinic lattice with space group P 1 21/c 1 for all compositions. The Rietveld procedure also confirms the single phase and monoclinic structure of synthesized phosphors. Fourier-transform infrared) spectroscopy confirms compositional homogeneity. FE-SEM micrographs show irregularly stacked microstructures and morphology for all compositions irrespective of Sm3+ doping percentage. While EDS and Elemental mapping confirm uniform incorporation of Sm3+ ions in phosphors lattice. Diffuse Reflectance Spectra studies show Sm3+ doping resulted in redshift and band gap narrowing. In Photoluminescence spectroscopies, excitation and emission spectra reveal that distinctive photoluminescence spectra with notable emission peaks at 402 nm (6H5/2 → 4F5/2) and 599 nm (4G5/2 → 6H5/2). CIE chromaticity coordinates demonstrated varied color purity and coordinates for different doping levels, with promising orange-red emissions and increased luminosity. The observed optical properties suggest the potential suitability of Sm3+-activated NaZnPO4 phosphors as promising candidates for enhancing WLED efficiency and color quality.

Multiwavelength Excitation in Ho3+-Doped All-Inorganic Double Perovskites Achieved by Codoping Mn2+ for Warm-White LEDs and Plant Growth.

Doping lanthanide ions is an efficient method to modify the optical properties of lead-free double-perovskite halides. However, most lanthanide-doped double perovskites show a low luminescence efficiency and require a high excitation energy. Here, we have successfully prepared a series of Ho3+-doped Cs2NaBiCl6 microcrystals through a simple hydrothermal method and obtained strong characteristic emissions of Ho3+ at 492 and 657 nm under low-energy excitation (449 nm). After codoping Mn2+, apart from the characteristic emissions from Ho3+ under 450 nm wavelength excitation, the orangish-red luminescence consisting of the emission band centered at 591 nm from Mn2+ and a sharp emission peak at 657 nm from Ho3+ is obtained under 355 nm UV light excitation. Photoluminescence (PL) emission and excitation spectra, along with the PL decay curves, confirm the existence of an energy-transfer channel from Cs2NaBiCl6 to Mn2+ and then from Mn2+ to Ho3+. The enhanced absorption efficiency (10.5 → 70.7%) suggests that the codoping of Mn2+ overcomes the low absorption efficiency caused by f-f forbidden transitions of Ho3+. Finally, the diverse luminescent performance within the Cs2NaBiCl6:Ho3+, Mn2+ phosphor is realized by altering the excitation wavelength, thereby enabling its application in warm-white-light-emitting diodes and plant growth in this work.

Robust Free Excitons in CH3NH3PbI3 Halide Perovskite Revealed by Four‐Wave Mixing

AbstractDirect bandgap semiconductors possess a unique attribute: the presence of a free exciton state with a high total oscillator strength. This property makes them highly promising for applications in ultrafast optical signal processing and optical computing. One such protocol for optical computing is based on four‐wave mixing (FWM). In this study, the nonlinear optical effect in polycrystalline thin films of halide perovskite MAPbI3 (MA+ = CH3NH) at low temperatures is demonstrated. Through analyzing the spectroscopy of the FWM signal, studying the photoluminescence excitation spectra, and comparing the findings with results from MAPbI3 single crystals, it has been discovered that the strongest nonlinear response is observed at the free exciton resonance and in the region of shallow defect states. Surprisingly, the presence of FWM in cross‐linear excitation geometry has been observed, indicating potential involvement of other nonlinear or many‐body effects. The observations of FWM with free excitons even in highly defective MAPbI3 thin films demonstrate the robustness of the exciton resonance and highlight the practical prospects for utilizing this material in optical computing.

Microwave-assisted combustion synthesis and characterization studies of novel dysprosium doped yttrium calcium borate (Dy3+: Y2CaB10O19) phosphor materials for efficient white light applications

Micro-wave assisted combustion synthesis technique was adopted to synthesize the dysprosium-doped yttrium calcium borate xDy3+: Y(2-x) CaB10O19 (Dy:YCB) polycrystalline phosphor materials with varying concentrations (x = 1, 3, 5, 7 and 9 mol %) for the first time. The formation of phase, crystal structure was analyzed by x-ray diffraction study and was affirmed to be formed pertaining to the monoclinic crystal structure (a = 11.475 Å, b = 6.345 Å, c = 9.223 Å and α = γ = 90°, β = 91.83°) with C2 space group. The absorption capability of the prepared samples was investigated by UV-DRS spectroscopy and the optical band gap was found to be 5.28 eV. FTIR study validated the presence of functional groups and their molecular vibrations. The excitation wavelength of the synthesized samples was found to be 350 nm from photoluminescence excitation (PLE) spectra. The PL emission spectra were recorded to authenticate the emission wavelengths and found to possess two emission peaks at 480 nm (blue) and 577 nm (yellow) contributed by the Dy3+ ions. The optimized dopant concentration of dysprosium ion was fixed at x = 0.07 to avoid the concentration quenching effect. The chromaticity co-ordinate of optimized sample was determined to be x = 0.3188, y = 0.3233 which are closer to ideal white light co-ordinate. The color temperature was determined to be 6209 K, which occurs in the cool white light region. Luminous efficacy of radiation (LER) was determined to be 269.31 l m/Wopt for the optimal phosphor. The luminous efficiency for the optimal phosphor was determined to be 40%. Color rendering index (CRI) of the optimal sample was evaluated to be 77. Internal quantum yield (IQE) of the optimal sample was determined to be 50.58 %. The phosphor materials have excellent thermal stability as validated from the temperature dependent PL measurements.

Luminescence of silver, thulium and ytterbium doped oxyfluoride glasses

Abstract Silver and lanthanide (Tm3+, Yb3+) doped oxyfluoride glasses have been prepared by melt-quenching method. The absorption of the glasses was measured in the range from 350 to 550 nm revealing the absorption edges of Ag nanoclusters and Tm3+ transition. The photoluminescence spectra of the glasses were detected in the range from 400 to 1100 nm under excitation in the range from 300 to 500 nm. The photoluminescence excitation spectra showed that Ag nanoclusters and Tm3+ ions can effectively harvest energy in UV-range and convert to visible and infrared (through emission by Yb3+ ions) ranges making the glasses perspective as white light emitters and solar spectrum downconverters.

A Bifunctional Luminescent Whitening and Sensing Material Based on Photoluminescence and Mechanoluminescence.

A bifunctional luminescent whitening and luminescent sensing composite material, BaMgAl12O17:Eu2+/polydimethylsiloxane (BAM/PDMS), that utilizes natural sunlight and mechanical energy is presented. By increasing the Eu2+ content, the photoluminescence (PL) excitation spectrum of the material shows a maximum redshift of 23 nm due to 5d level splitting of Eu2+, resulting in more spectral overlap with sunlight and an excellent PL whitening effect. Meanwhile, the self-recoverable mechanoluminescence (ML) of the material can be easily excited under mechanical stimuli due to contact electrification, exhibiting a unique stress sensing effect. Based on the unique features of PL whitening and ML sensing, the material is applied to model cars through a spray process, and the results demonstrate that the bifunctional BAM/PDMS material shows promising applications in automobile decoration.

Progress towards blue emitting MgO-ZnO-Ga2O3 nanocomposites synthesized by bio mediated route

MgO-ZnO-Ga2O3 nanocomposites are synthesized by solution combustion method using Aloe Vera gel as a reducing agent to increase the efficiency of blue emission. The appearance of Bragg reflections corresponding to MgO, ZnO and Ga2O3 clearly indicates the formation of nanocomposites. The surface morphology consists irregular shape and sized NPs. The Energy dispersive X-ray analysis confirms the purity of the sample. The band energy gap was tuned to 3.1 eV. The Photoluminescence excitation and emission spectra was discussed and compared it with emission spectra of individual oxides as well as with other reported blue emitted nanophosphors. Further, the chromaticity coordinates and Color correlated temperature coordinates clearly confirms their warm blue emission. Further, the powder dusting method was employed to collect the latent fingerprints on the pores and non-pores surfaces. The synthesized MgO-ZnO-Ga2O3 nanocomposites exhibits well-resolved ridge patterns that can be used to identify latent finger prints with clarity. From all these results, the present synthesized MgO-ZnO-Ga2O3 nanocomposite might find an application in display technology as a blue nanophosphor material and for latent finger print detection in crime investigation.

Phase composition and luminescent properties of cesium lead bromide perovskite nanopowders

Halide perovskite nanopowders were synthesized by ligand-assisted re-precipitation technique with different volume ratios of mixture solution to antisolvent (toluene). It was found that with an increase in the proportion of toluene, the phase formed as a result of recrystallization changes predominantly from Cs4PbBr6 to the CsPbBr3, while less stable CsPb2Br5 phase was also discovered. The change in the phase composition of powders obtained with different volume ratios of mixture solution to toluene is explained by the salting out effect of slightly soluble compounds. The phase composition had a correlation with the crystal size distribution, as well as with the photoluminescence quantum yield. Optical properties, including absorption spectra, photoluminescence excitation and luminescence spectra were investigated. Nanopowders obtained with a ratio of the mixture of solution to toluene of about 1:0.9 had the maximum quantum efficiency. The following was associated with the formation of low-dimensional CsPbBr3 “slabbed” crystals sticked on rhombohedral Cs4PbBr6 crystals. The composite film based on nanocrystals and thermoplastic polyurethane was made by hot pressing, the potential of its use as a phosphor coating for an ultraviolet LED was shown.