Cr3+/Bi3+ co-doped and Cr3+/Yb3+ co-doped La2LiSbO6 phosphors have been synthesized via a high-temperature solid-state method, respectively. La2LiSbO6: Cr3+ gives a broadband emission peaking at 855 nm under 671 nm excitation. Partial substitution of La3⁺ ions by Bi3+ ions induces lattice distortion in the La2LiSbO6 host and weakens the crystal field strength of Cr3+, leading to the red shift of Cr3+ emission. The Cr3+ emission peak shifts from 855 to 900 nm with Bi3+ concentration increasing from 0 to 0.07 mol

Near-infrared pc-LEDs are a promising light source for various applications including bio-imaging, night vision monitoring, environmental surveillance and plant cultivation, offering advantages such as low cost, wide emission spectra and compact design. The development of high-performance NIR phosphors is of great significance to the advancement of NIR pc-LEDs. In this work, the luminescence properties of NIR phosphor Li2MgZrO4:0.01Cr3+ have been effectively improved by Ga3+ doping. Under excitation of 445 nm blue light, the emission intensity of the Li2MgZr0.75O4:0.01Cr3+,0.25Ga3+ phosphor is 2.61 times that of its Ga3+ free counterpart. The internal quantum efficiency (IQE) increases from 28.8% to 35.3%, and the external quantum efficiency (EQE) increases from 6.2% to 12.7%. The temperature stability of the Li2MgZr0.75O4:0.01Cr3+,0.25Ga3+ phosphor is also improved. The increased structural rigidity and crystal field strength of Cr3+ induced by doped Ga3+ ions are responsible for the better luminescence properties. The improved phosphor has the potential for use in NIR light sources.

Self-activated purple luminescence at 385 nm originating in vacancy defects in NaLa₄(SiO₄)₃F synthesized under reducing atmosphere is observed under excitation of 320 nm for the first time. Ce3+ ions doped in NaLa₄(SiO₄)₃F exhibit PLE and PL spectra that are highly similar to the vacancy defects in it. The emission intensity of Tb3+ and Dy3+ doped in NaLa₄(SiO₄)₃F can be improved by 11 and 7.5 times under 315 nm excitation, caused by the co-sensitization energy transfers from vacancy defects and Ce3+ ions to Tb3+ and Dy3+ ions. By adjusting the concentrations of Tb3+ and Dy3+, the luminescence color of NaLa₄(SiO₄)₃F: Ce3+, Tb3+ and NaLa₄(SiO₄)₃F: Ce3+, Dy3+ phosphors can be tuned from violet to green and from violet to white, respectively. It is found that the NaLa₄(SiO₄)₃F: Ce3+, Tb3+/Dy3+ series phosphors exhibit potential application prospects in ultraviolet pc-WLEDs, optical temperature sensing and fluorescence anticounterfeit.

Phosphors emitting cyan-green light with a small Stokes shift under blue light excitation is crucial for addressing spectral deficiencies in phosphor-converted white light-emitting diodes (pc-wLEDs). In this work, a series of Mg2+ ion doped and Mg2+-Th3+ (Th--Ga,In) ion pair co-doped Ca8MgSi4O16Cl2: Eu2+ phosphors were synthesized using a high-temperature solid-phase reaction method. It is found that the doped Mg2+ ions can improve the local environment of Eu2+ ions thus enhance its luminescence, while the doped Th3+ (Th--Ga,In) can regulate the distribution of Eu2+ ions occupying hexa-coordinated and octa-coordinated Ca2+ sites. It is proven that co-doping Mg2+-Ga3+ ion pair facilitates more Eu2+ ions enter the octa-coordinated Ca2+ sites, which largely enhances the cyan-green emission intensity. A pc-wLEDs device with a color rendering index (CRI) of 97.2 and a correlated color temperature (CCT) of 3480K has been fabricated combining the present Ca7Ga0.9Mg1.9Si3.1O16Cl2:0.1Eu2+ phosphor, commercial yellow and red phosphors with blue LED chip. It is found that Ca7Ga0.9Mg1.9Si3.1O16Cl2:0.1Eu2+ phosphor can partially fill the cyan gap of the pc-wLEDs spectra, enhancing the emission quality of the pc-wLEDs device.

Effects of Ce3+ doping on the photoluminescence, photostimulated luminescence, long persistent luminescence and thermoluminescence of Sr4Al14O25:0.05Eu2+, 0.08Tm3+ phosphors are systematically investigated. It is found that the doped Ce3+ ions not only introduce new shallow traps, but also increase the original deeper trap depth in Sr4Al14O25:0.05Eu2+, 0.08Tm3+, simultaneously improving the long afterglow and optical storage performance of the phosphor. Especially, the optical storage capacity of the Sr4Al14O25:0.05Eu2+, 0.08Tm3+, 0.05Ce3+ phosphor increases by 52 % compared with that of the Ce3+-free phosphor. The mechanism for the Ce3+ doping introduced improvement of long persistent luminescence and photostimulated luminescence of Sr4Al14O25:0.05Eu2+, 0.08Tm3+, Ce3+ is discussed. By mixing the phosphor with silica gel, a flower pattern is made to simulate the image information storage, proving the great application prospect of Sr4Al14O25:0.05Eu2+, 0.08Tm3+, 0.05Ce3+ for optical storage.

Broadband near-infrared (NIR) phosphors with external quantum efficiency exceeding 50% are still extremely scarce. In this work, the introduced Li+ ions replacing Ga3+ sites and B3+ ions occupying interstitials synergistically improve the local environment of Cr3+ in Ga1.6Sc0.4O3 (GSO) host, raising its external quantum efficiency from 42.3 to 51.9%. The NIR phosphor-converted light-emitting diode (pc-LED) fabricated by combining the optimized GSO: Cr3+, Li+, B3+ phosphor with 450 nm LED chip shows photoelectric efficiency of 34.14% at 5 mA, indicating that the improved GSO:Cr3+, Li+, B3+ phosphor has excellent potential for broadband NIR light source application.

Accurate prediction of emission spectra is critical for designing high-performance hybrid phosphors. This paper proposes a novel data-driven approach combining XGBoost with Newton-Raphson-based Optimization (NRBO) for emission spectrum prediction of mixed phosphors. The method integrates particle encoding and objective function optimization to enhance model performance. Experiments are conducted on the $\mathbf{3 d}^{\mathbf{3}}$ ions $\left(\text{Mn}^{4+}, \text{Cr}^{3+}\right)$ activated phosphors database, predicting both 2E $\rightarrow$ 4A2 and 4T2 → 4A2 emission maxima. Results demonstrate that the proposed NRBO-XGBoost model achieves superior performance with an $\mathbf{R}^{\mathbf{2}}$ of $\mathbf{0. 9 9 9 9 8 3}$, MSE of $\mathbf{0. 0 0 0 2 6 1}$, and RMSE of 0.0153, significantly outperforming traditional methods including Ridge, Lasso, KNN, and Random Forest. Ablation studies confirm the effectiveness of the NRBO module, while sensitivity analysis validates model robustness across various hyperparameter configurations. This framework provides an efficient and reliable tool for spectral prediction in phosphor materials research.

Highly selective, sensitive, and fast hydrogen sensing technology is becoming increasingly important in the processes of production, transportation, and usage of hydrogen energy. Field-effect transistor (FET) is the basic element of modern IC. When serving as a gas sensor, FET poses advantages of small size, high sensitivity, and low power consumption. This article reviews the latest developments in FET hydrogen sensors based on channel materials from traditional silicon, III-V compound semiconductors to novel channel materials carbon nanotubes, graphene, and two-dimensional black phosphorus. Firstly, the structure of FET sensors was investigated. Then the sensitive materials severing as gate were reviewed and efforts to improve the performance was summarized. Then, we discuss the sensitive materials that are currently available, with a focus on the interaction mechanisms between hydrogen and the sensitive materials. Lastly, methods to enhance sensor performance by modifying the physical and chemical properties of the sensitive materials are presented. Finally, the article provides an outlook on the future development of FET type hydrogen gas sensing.

Cr3+ near infrared (NIR) emission is witnessed in tellurite compound for the first time. Broadband emission that peaks at 840nm and has 157 nm of full width at half maxima (FWHM) appears in the Cr3+ doped In2TeO6 phosphor when excited at 455 nm. Further introduction of Li+ ions into the In2TeO6 can distort the octahedral environment of the doped Cr3+ ions, resulting in 4 times enhancement in luminescence intensity and a 1.75-fold enhancement in internal quantum efficiency (IQE). Moreover, the FWHM increases to 282nm in the In2TeO6: Cr3+,Li+,Yb3+ phosphor induced by the Cr3+ to Yb3+ energy transfer. LED device utilizing this NIR phosphor has been constructed. At 150 mA drive current, the optoelectrical efficiency is 11.189% and the NIR output power is 50.72 mW. The In2TeO6: Cr3+,Li+,Yb3+ phosphor exhibits enormous potential in NIR phosphor-converted LED (pc-LED).

Cr 3 + near infrared (NIR) emission is witnessed in tellurite compound for the first time. Broadband emission that peaks at 840 nm and has 157 nm of full width at half maxima (FWHM) appears in the Cr 3 + doped In 2 TeO 6 phosphor when excited at 455 nm. Further introduction of Li + ions into the In 2 TeO 6 can distort the octahedral environment of the doped Cr 3 + ions, resulting in 4 times enhancement in luminescence intensity and a 1.75-fold enhancement in internal quantum efficiency (IQE). Moreover, the FWHM increases to 282 nm in the In 2 TeO 6 : Cr 3 + ,Li + ,Yb 3 + phosphor induced by the Cr 3 + to Yb 3 + energy transfer. LED device utilizing this NIR phosphor has been constructed. At 150 mA drive current, the optoelectrical efficiency is 11.189 % and the NIR output power is 50.72 mW. The In 2 TeO 6 : Cr 3 + ,Li + ,Yb 3 + phosphor exhibits enormous potential in NIR phosphor-converted LED (pc-LED).

A series of Ni2+/Tm3+ codoped MgGa2O4 phosphors were prepared using a conventional high-temperature solid-state method. A strong NIR up-conversion emission around 801 nm is exhibited in the Ni2+/Tm3+ codoped MgGa2O4 phosphor under excitation of 1064 nm, with a marked advantage over a blue up-conversion emission near 476 nm, indicating that the Ni2+/Tm3+ codoped MgGa2O4 is an excellent pure NIR to NIR up-conversion phosphor. The NIR up-conversion intensity of the Ni2+/Tm3+ codoped MgGa2O4 can be enhanced by approximately 200 times compared to the Tm3+ single-doped one. It is proven that the energy transfer from Ni2+ to Tm3+ caused by radiative reabsorption performs the up-conversion. The results suggest that the newly developed up-conversion material in the present work may be considered as a candidate for applications such as bioimaging, efficiency enhancement of solar cells, and infrared detection.

Currently Cr3+ ion-activated broadband near-infrared (NIR) phosphors for phosphor-converted light-emitting diodes (pc-LEDs) are receiving much attention. However, developing a high quantum yield (QY) and excellent luminescence thermal stability of Cr3+ ion-activated phosphors with an emission peak exceeding 850 nm is still a great challenge. In the present work, ZrTe3O8:Cr3+ (ZTO:Cr3+) phosphor has been prepared via a high-temperature solid-state reaction method, and its NIR emission wavelength ranges from 700 to 1200 nm with peak 889 nm and full width at half-maximum (fwhm) up to 195 nm under 455 nm light excitation. Partial substitution of Zr4+ ions by Ti4+ in the phosphor enhances the luminescence intensity by 1.65-fold. The optimized ZTO:Cr3+, Ti4+ phosphor exhibits an internal quantum efficiency (IQY) of 64.9% and the emission intensity remains at 73.82% of the room temperature (298 K) when the temperature is increased to 423 K. This indicates that the long-wavelength broadband NIR phosphor developed in the present work exhibits both excellent thermal stability of luminescence and high IQY, which is promising for night vision, nondestructive testing, and bioimaging applications.

Ni2+ doped and Ni2+/Er3+ co-doped Gd2MgTiO6 (GMT) phosphors have been synthesized by conventional high-temperature solid-state reaction method. First-principles calculation and X-ray diffraction analysis proves that Ni2+ ions occupy the Mg2+ sites in the Gd2MgTiO6 matrix at low Ni2+ doping concentration and begin to occupy Ti4+ sites at high Ni2+ doping concentration. The near infrared emissions of Ni2+ ions occupying Mg2+ and Ti4+ sites peak at 1344 nm and 1412 nm, respectively, forming a broad near infrared emission band from 1100 nm to 1700 nm. It is found that Ni2+/Er3+ co-doped Gd2MgTiO6 phosphor is capable to up-convert near infrared photons in the wavelength range of 870-1700 nm to visible 532 nm, 555 nm and 666 nm emission, caused by the energy transfer sensitization process from Ni2+ to Er3+. The Ni2+ and Er3+ concentration dependent up-conversion properties have been investigated and it is found that the Gd2MgTiO6: 2%Ni2+/5%Er3+ phosphor shows the strongest up-conversion emission, in which the energy transfer efficiencies from the Ni2+ ions occupying Mg2+ and Ti4+ sites to the Er3+ ions are 81.5% and 79.3%, respectively. The Gd2MgTiO6: 2%Ni2+/5%Er3+ phosphor shows yellow emission under the irradiation of 1342 nm and 1550 nm lasers, and green and orange-red emissions under the irradiation of 980 nm and 1064 nm laser, respectively. The broad band excitability and multi-color up-conversion performance of the Ni2+/Er3+ co-doped Gd2MgTiO6 phosphor suggest that it has wide application prospect in anti-counterfeiting, solar cell efficiency enhancement, infrared detection and so on. (c) 2023 Elsevier B.V. All rights reserved.

NaGd (1-x-y) Tb x Eu y SiO 4 phosphors were synthesized through high-temperature solid-state reaction method. The effects of doping concentration and temperature of Tb 3+ and Eu 3+ doped NaGdSiO 4 on the luminescence performance are investigated in detail. Eu 3+ luminous intensity enhancement and excitation spectra expansion are realized through efficient energy transfer of Tb 3+ → Eu 3+ . The luminous color is regulated from green to red by altering the concentration of Tb 3+ and Eu 3+ . The temperature measurement performance of the NaGd 0.85 Tb 0.1 Eu 0.05 SiO 4 phosphor has also been witnessed. In the temperature range of 273 K − 483 K, the maximum absolute and relative sensitivity are 0.008 K −1 and 0.533%K −1 , respectively. It is evident that NaGd (1-x-y) Tb x Eu y SiO 4 phosphors are available for temperature measurement.

Dual emissionNaLaMgWO(6):Mn4+, Tb3+ phosphor has been synthesized via high temperature solid state reaction method. The phosphor shows both red Mn4+ emission and green Tb3+ emission and its emission color can change from red to green by adjusting the ratio of Mn4+/Tb3+ doping concentration. Moreover, the luminescence intensity ratio of Tb3+/Mn4+ exhibits a monotonic relationship with both temperature and excitation wavelength within certain range, meaning its possible application in optical temperature sensing and wavelength detection.

B3+ and Ca2+ ions in Ca2B5O9Cl host are replaced by Al3+ and Ba2+ ions, respectively, in order to change the host environment of Eu2+ for improving its luminescence properties. It is found that the blue emission centered at 453 nm under 410 nm excitation is increased by 28% at the Al3+ doping concentration of 14 mol% and Ba2+ doping concentration of 20 mol%. The luminescence intensity at 150 degrees C for the modified phosphor could maintain 67% of that at room temperature, indicating its good thermal stability. By combining a 410 nm near -ultraviolet chip with the blue phosphor developed in the present work, a red phosphor (SrxCa1-xAlSiN3:Eu2+), and a yellow-green phosphor (Y3Al5-xGaxO12:Ce3+), a pc-WLED device is fabricated, which can give warm white emission with CIE coordinate of (0.3847, 0.3888), and has high color rendering index (Ra = 97.4) and low correlated color temperature (CCT = 3978 K) at 3 V driving voltage.

Dual emission NaLaMgWO 6 :Mn 4+ , Tb 3+ phosphor has been synthesized via high temperature solid state reaction method. The phosphor shows both red Mn 4+ emission and green Tb 3+ emission and its emission color can change from red to green by adjusting the ratio of Mn 4+ /Tb 3+ doping concentration. Moreover, the luminescence intensity ratio of Tb 3+ /Mn 4+ exhibits a monotonic relationship with both temperature and excitation wavelength within certain range, meaning its possible application in optical temperature sensing and wavelength detection.

A series of Mn 4+ , Nd 3+ codoped K 0.5 La 0.5 SrMgWO 6 phosphors have been prepared by high‐temperature solid‐state reaction method. Under 468 nm excitation, near infrared emission bands centered at around 910 and 1064 nm are observed, assigned to the 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions of Nd 3+ , respectively. The similarity between the excitation spectra in the 300–550 nm monitored at Mn 4+ 697 nm emission and those monitored at Nd 3+ 1064 nm emission as well as the lifetime shortening of Mn 4+ emission with Nd 3+ concentration increasing prove that the occurrence of the energy transfer sensitization from Mn 4+ to Nd 3+ . In terms of the analysis results based on Dexter's theory and Inokuti‐Horayama model, it is believed that the dipole–dipole interaction plays a key role in the energy transfer process.

A novel deep-red emitting phosphor K0.5La0.5SrMgWO6: Mn4+ has been designed by A-site multi cations substitution strategy. The K0.5La0.5SrMgWO6: 1.5%Mn4+ emits red luminescence peaking at 695 nm under NUV/Blue light excitation and exhibits outstanding quantum efficiency (IQE=92.4%, EQE=72.5%), which is comparable to the commercial red fluoride phosphor K2SiF6: Mn4+. It is believed that three different cations K+, Sr2+ and La3+ in the matrix tilt and distort the [WO6] and [MgO6] octahedrons, resulting in the enhancement of oscillator strength of transition for Mn4+ ions doped into the W6+ and Mg2+ sites and the reduction of concentration quenching induced by the energy transfer between Mn4+ ions. The K0.5La0.5SrMgWO6: Mn4+ phosphor might provide application in plant cultivation LEDs and the related investigation also refers an effective way to improve Mn4+ activated perovskite phosphor.

Visible up-conversion is observed in the Ni2+, Er3+, Nb5+ tri-doped Y2Mg3Ge3O12 phosphor under excitation of light within its broad absorption band (900–1700 nm) such as 980 nm, 1064 nm, 1342 nm and 1550 nm.