Structure and luminescence characteristics of self-activated vanadate garnet phosphors.

Vanadate phosphors include [VO] tetrahedra with symmetry. Due to the charge transfer (CT) between V-O, the phosphor with [VO] tetrahedra exhibits strong emission in the visible region and can effectively absorb ultraviolet (UV) light. Garnet structured vanadate phosphors have attracted much attention due to their easily controllable composition.

Investigation of SrBO:Tm luminescence for temperature imaging with high sensitivity based on time-resolved luminescence.

In recent years, with the growing demand for non-contact and real-time optical temperature measurements, it has become imperative to develop new luminescent thermometry materials as well as novel temperature detection schemes with higher sensitivity. In this work, a series of SrBO:Tm ( = 0.001-0.

Structural characterization of Li(MgZn)WO for bluish-white luminescence in rare earth-free tungstate phosphors.

Self-activated phosphors have attracted considerable attention due to their low synthesis temperature, high excitation threshold, and broad emission spectrum. And self-activated tungstate phosphors are distinguished by their low cost and stable chemical properties. Generally, it is difficult to observe luminescence from tungstate phosphors at room temperature.

Thermal imaging study of Sm doped SrBO based on time-resolved technology.

Thermal imaging materials with high sensitivity and the ability to reflect real-time temperature play an important role in research areas such as biotechnology and electronic engineering. However, the temperature sensitivity and temporal resolution of the current materials are not suitable for the complicated detection situation. In this paper, we introduce a thermal imaging material - SrBO:5%Sm - with high temperature sensitivity.

Investigation of the luminescence properties and energy transfer mechanisms in GdTaO:Bi,Eu phosphors for their potential application in full-spectrum WLEDs.

In recent years, there has been increasing effort devoted to the development of single-phase white phosphors due to drawbacks such as severe reabsorption and color deviation in traditional white light-emitting diodes (WLEDs). A new feasible strategy has emerged for achieving white light emission through the Bi-Eu energy transfer in suitable single-phase phosphors. Therefore, a series of GdTaO:Bi and GdTaO:0.

Investigation of multicolor emitting CsGdGeO:Bi,Eu phosphors energy transfer for WLEDs.

Bi/Eu doped CsGdGeO luminescent materials were prepared by a solid-state reaction. The energy band and density of states of CsGdGeO were calculated by density functional theory. The CsGdGeO host presents a broadband emission peaking at 520 nm.

Enhancing the luminescence performance of an LED-pumped Mn-activated highly efficient double perovskite phosphor with A-site defects local lattice tuning.

Altering the local symmetry of an activator by lattice tuning is considered an effective strategy to optimize the luminescence performance of phosphors. Herein, the novel Mn-activated double perovskite phosphor LaMgTaO (LMTO) with A-site defects was successfully prepared. Benefiting from the random occupation of the nearest A-site by cations and vacancies, the distorted [MnO] octahedra lack the inversion center.

Enhanced luminescence and tunable color in [Eu, Si]/Mn doped KBaCa(PO) based on charge compensation and energy transfer.

Recently, using the Eu2+ → Mn2+ energy transfer strategy to explore new single-phase phosphors suitable for the near-ultraviolet (n-UV) region has become one of the major strategies in solid-state lighting applications. Therefore, a novel color-tunable K2BaCa(PO4)2 (KBCPO):[Eu2+,Si4+],Mn2+ phosphor was developed because of the preeminent thermal stability of luminescence of Eu2+-activated KBCPO. In this study, we first designed a [Eu2+, Si4+] → [K+, P5+] charge compensation strategy to optimize the luminescence properties of Eu2+ in the KBCPO matrix.

Magnetron sputtered ZnO electron transporting layers for high performance perovskite solar cells.

An ideal electron transporting layer (ETL) of perovskite solar cells (PSCs) requires reasonable energy levels, high electrical conductivity and excellent charge extraction. The low processing temperature makes ZnO a promising ETL for PSCs; however the widely used solution-processed ZnO films often suffer from high-density surface defect states, which might cause severe charge recombinations at the ETL/perovskite interface and accelerate the chemical decomposition of perovskite materials. In this work, we employed the vacuum-based magnetron sputtering method to deposit ZnO ETLs, which significantly reduces the number of oxygen vacancies and hydroxyl groups on the ZnO surface.

Investigation of the thermal quenching of two emission centers in SrMnLi(PO):Eu using time-resolved technique.

The thermal stability of the phosphors in phosphor-converted light-emitting diodes (LEDs) plays an important role in the practical application of lighting. Herein, the Mn-based red-emitting phosphors of pure and Eu-doped SrMnLi(PO) (SMPO) samples were prepared using the high temperature solid-state reaction method. The crystal field environment around the Mn ions was analyzed by combining the results of photoluminescence excitation spectroscopy and Tanabe-Sugano diagrams.

A study on temperature sensing performance based on the luminescence of Eu and Er co-doped YNbO.

Eu3+ and Er3+ co-doped YNbO4 powder phosphors were synthesized by a traditional high-temperature solid-state reaction method. A laser of 487.6 nm wavelength was selected to be the excitation source which can pump Eu3+ ions from its thermally populated low-lying 7F2 ground state to the excited state 5D2 and lift the Er3+ ions from their 4I15/2 to 4F7/2 states.

Temperature-dependent persistent luminescence of SrAlO:Eu, Dy, Tb: a strategy of optical thermometry avoiding real-time excitation.

A new strategy of optical thermometry is realized by long persistent luminescence phosphor SrAlO:Eu, Dy, Tb (SAEDT). Under different temperatures, SAEDT shows bright afterglow emissions after cessation of the UV excitation. The afterglow color of the SAEDT sample is blue at 60 K and gradually changed into green at 240 K.

Highly uniform and monodisperse β-NaYF : Sm nanoparticles for a nanoscale optical thermometer.

Monodisperse β-NaYF:1%Sm nanoparticles were fabricated successfully via the thermal decomposition technique. Strong temperature dependence of the Sm emission was observed when its thermally populated state H6 was directly excited to the G4 level. This strategy not only can eliminate laser heating and background Stokes-type scattering noise but also has a high quantum yield as a result of one-photon excitation process.

Luminescence properties and the thermal quenching mechanism of Mn doped ZnGeO long persistent phosphors.

Cation doped ZnGeO materials have been intensively explored owing to their excellent performance in photocatalysts, optoelectronic devices and white light-emitting diodes. However, the luminescence process and thermal quenching arising during the optical excitation of these materials are yet to be clarified. The pure and 2% Mn doped ZnGeO phosphors were prepared via the high temperature solid state reaction.

Investigation on the site occupation of rare-earth ions in CaInO with the fluorescence probe of Eu.

Rare-earth doped CaInO phosphors have been widely investigated due to their excellent luminescent property, but the site occupation of rare-earth ions in CaInO is not very clear and needs to be clarified. Using Eu as a fluorescence probe, such a clarification has been made in this work. 1% and 2% Eu doped CaInO powder samples have been prepared by the sol-gel method.

Temperature Sensing Using Thermal Population of Low-Lying Energy Levels with (SmGd)VO.

A temperature sensing scheme is proposed that is based on the dramatic temperature dependence of the photoluminescence when Sm dopants are excited from thermally populated H levels, rather than the ground level H, to the G luminescent level. The scheme has the advantage of eliminating laser heating and background Stokes-type scattering noise. Experimental realization was carried out on a (SmGd)VO sample by detecting the intensities at 550-580 nm using excitation wavelengths of 601.

Real-time micro-scale temperature imaging at low cost based on fluorescent intensity ratio.

Real-time temperature imaging with high spatial resolution has been a challenging task but also one with wide potential applications. To achieve this task, temperature sensor is critical. Fluorescent materials stand out to be promising candidates due to their quick response and strong temperature dependence.

Investigation of SrBO:Sm as a Multimode Temperature Sensor with High Sensitivity.

Sm-doped SrBO was synthesized for high-sensitivity thermometry. A high thermal-sensitive fluorescence intensity ratio and fluorescence lifetime were achieved in a wide temperature range. At 500 K, the relative sensitivity of the temperature sensing was 2.

Nonlinear Composition-Dependent Optical Spectroscopy of Ba2xSr2-2xV2O7.

In general, adjusting the composition of a fluorescent material is an effective way to tune its luminescent properties such as peak energy and bandwidth. In most solid-solutions, the emission peak shifts linearly with the materials' composition, which is referred to as Vegard's Law. However, we found extraordinary variations in our samples Ba2xSr2-2xV2O7, that is, both the excitation and emission peaks show nonlinear dependence on the composition x, and the same is true for the spectral bandwidths.

Local Environment Study of Eu3+ Doped KGd2F7 by Site-Selective Spectroscopy.

The site-selective spectra and decay curves at 20 K of Eu3+ ions doped KGd2F7 were measured to study the local environment of the Eu3+ sites. The experimental results show that Eu3+ ions occupy three types of sites in the KGd2F7 host. And Eu3+ ions in different types of sites exhibit quite distinct emission spectra and have remarkably different 5D0 level decay lifetimes.

Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity.

Temperature sensor based on ladder-level assisted thermal coupling and thermal-enhanced luminescence in NaYF4: Nd³⁺.

NaYF4: Nd³⁺ microprisms were synthesized by a hydrothermal method. The bands of near-infrared (NIR) luminescence originating from the 4F3/2, 4F5/2 and 4F7/2 levels of Nd³⁺ ions in NaYF4: Nd³⁺ microcrystals were measured under 574.8 nm excitation at various temperatures from 323 to 673 K.

Strategy for thermometry via Tm³⁺-doped NaYF₄ core-shell nanoparticles.

Optical thermometers usually make use of the fluorescence intensity ratio of two thermally coupled energy levels, with the relative sensitivity constrained by the limited energy gap. Here we develop a strategy by using the upconversion (UC) emissions originating from two multiplets with opposite temperature dependences to achieve higher relative temperature sensitivity. We show that the intensity ratio of the two UC emissions, ³F(2,3) and ¹G₄, of Tm³⁺ in β-NaYF₄:20%Yb³⁺, 0.

Synthesis and luminescence properties of NaSrPO4:Eu2+, Tb3+, Mn2+ for WLED.

In order to obtain a single-host-white-light phosphor used for near ultraviolet (NUV) light emitting diodes (LEDs), the NaSrPO4:Eu2+, Tb3+, Mn2+ powder samples were synthesized via a high temperature solid-state reaction. XRD investigation shows a single phase. Energy transfer processes is discussed by analyzing the photoluminescence (PL) and photoluminescence excitation (PLE) spectra.

Synthesis and photoluminescent properties of NaYF4:Eu3+ core and NaYF4:Eu3+/NaYF4 core/shell nanocrystals.

NaYF4:Eu3+ core and NaYF4:Eu3+/NaYF4 core/shell nanocrystals (NCs) were synthesized via a wet chemical method. The transmission electron microscope photographs show that the core and core/shell nanoparticles are monodisperse and uniform NCs with average diameters of 22 and 26 nm respectively. The photoluminescence (PL) properties of the samples, including the PL excitation and emission spectra, and luminescent decay curves, are investigated in detail.