Violet light excited white light emitting diodes (LEDs) have attracted widespread attention due to their advantages of tunable color temperature and visual comfort. However, high-performance phosphors suitable for violet light excitation (400-420 nm) have not yet been widely applied on a large scale. One of the key factors regarding the commercial utilizations is the stability. Unfortunately, there still lacks research on this issue. In this study, three rare-earth phosphors suitable for violet light excitation in LEDs were synthesized via a solid-state reaction method, namely K₂CaPO₄F:Eu²⁺, K_1.3Al₁₁O_17+δ:Eu²⁺ and Ca₂YHf₂Al₃O₁₂:Ce³⁺,Tb³⁺. The stability experiments were then conducted under conditions of high temperature and humidity, water immersion, and long-term violet light irradiation from LED chips. The luminescent properties, failure mechanisms, and environmental stability were analyzed. Finally, a white LED device was prepared by combining the as-synthesized three phosphors onto a 400 nm violet light chip. Results demonstrate that the as-synthesized phosphors exhibit not only optimized luminescence performance compared to phosphors prepared in former works, but also a more comprehensive evaluation of environmental stability across different conditions. The white LED device achieves a color rendering index of 93.6, a correlated color temperature of 5151 K and a color coordinate of (0.34, 0.36), showcasing excellent white light illumination performance. Furthermore, the environmental stability of the white LED device is improved compared to individual phosphors. By taking lead in investigating the environmental stability of violet light excited LED phosphors, this work provides valuable insights and guidance for advancing their applications.

Three to five μm mid-infrared laser has broad applications in atmospheric communication, environmental monitoring, medical treatment, and defense. Here, a series of glasses with compositions of 70TeO₂-25ZnO-5La₂O₃, doped with Dy³⁺ or Yb³⁺, and co-doped with Dy³⁺/Yb³⁺, were prepared using the melt-quenching method in an inert atmosphere-protected glovebox. Thermal properties, structural characteristics, hydroxyl content, and mid-infrared luminescence of the glasses were characterized through measurements such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman spectra, transmission spectra, and 3 μm band fluorescence spectra. The results indicate that 70TeO₂-25ZnO-5La₂O₃ glass possesses high resistance to crystallization (ΔT=101 ℃) and low phonon energy (760 cm^-1). Under 980 nm laser diode (LD) excitation, Dy³⁺/Yb³⁺ co-doped tellurite glass produces a broadband fluorescence emission around 3 μm region, with a full width at half maximum (FWHM) of 326 nm. This is attributed to the high energy transfer efficiency from Yb³⁺ to Dy³⁺ (98.74%) and the low hydroxyl absorption coefficient near 3 μm (0.32 cm^-1). Based on Judd-Ofelt and Dexter theories, spontaneous radiative transition probability, fluorescence branching ratio, and other spectroscopic parameters of Dy³⁺ ions, as well as microscopic parameters of Yb³⁺→Dy³⁺ energy transfer, were calculated. The primary energy transfer pathway is analyzed and identified as Yb³⁺: ²F_5/2→Dy³⁺: ⁶H_7/2, ⁶F_9/2. This study demonstrates that the low-hydroxyl Dy³⁺/Yb³⁺ co-doped TeO₂-ZnO-La₂O₃ glass can serve as an excellent 3 μm mid-infrared gain medium.

Perovskite quantum dots have unique advantages in display. However, their long-term stability at high brightness is still a huge challenge. Therefore, this article focuses on the progress of the regulation of perovskite quantum dots and their luminescent film morphology, explains the influence of long-range ordered perovskite quantum dot films on their electroluminescent properties, and looks forward to the development prospects in improving the electroluminescent stability of perovskite quantum dots.

As an essential candidate for environment-friendly luminescent quantum dots (QDs), CuInS-based QDs have attracted more attention in recent years. However, several drawbacks still hamper their industrial applications, such as lower photoluminescence quantum yield (PLQY), complex synthetic pathways, uncontrollable emission spectra, and insufficient photostability. In this study, CuInZnS@ZnS core/shell QDs was prepared via a one-pot/three-step synthetic scheme with accurate and tunable control of PL spectra. Then their ensemble spectroscopic properties during nucleation formation, alloying, and ZnS shell growth processes were systematically investigated. PL peaks of these QDs can be precisely manipulated from 530 to 850 nm by controlling the stoichiometric ratio of Cu/In, Zn²⁺ doping and ZnS shell growth. In particular, CuInZnS@ZnS QDs possess a significantly long emission lifetime (up to 750 ns), high PLQY (up to 85%), and excellent crystallinity. Their spectroscopic evolution is well validated by Cu-deficient related intragap emission model. By controlling the stoichiometric ratio of Cu/In, two distinct Cu-deficient related emission pathways are established based on the differing oxidation states of Cu defects. Therefore, this work provides deeper insights for fabricating high luminescent ternary or quaternary-alloyed QDs.

The all-inorganic CsPbX₃ (X=Cl, Br, I) perovskite nanocrystals have been widely applied in optoelectronic devices due to their excellent optoelectronic properties. However, their poor stability remains one of the main factors restricting their commercial development. This research focuses on improving the stability and solid-state luminescence performance of CsPbBr₃ nanocrystals. The porous MIL-53 (Al) metal-organic frameworks (MOFs) with outstanding hydrophobic properties was chosen as the encapsulation matrix. CsPbBr₃ nanocrystals were grown in situ within the MIL-53 (Al) channels by using a thermal injection process to successfully synthesize CsPbBr₃@MIL-53 nanocomposite phosphors with outstanding solid-state luminescence performance and high stability. MIL-53 chelates with CsPbBr₃ nanocrystals through benzene rings and organic ligands, firmly anchoring nanocrystals in the pores. This not only protects the CsPbBr₃ nanocrystals from external environmental influences but also effectively prevents aggregation between nanocrystals, thereby avoiding quenching of solid-state fluorescence. Additionally, the COO^- functional groups in MIL-53 bind with the unpaired Pb²⁺ on the surface of CsPbBr₃ nanocrystals, passivating the surface defects and suppressing non-radiative carrier recombination. Furthermore, the contained benzene rings and organic long chains endow the nanocomposite phosphors with excellent hydrophobic properties. The synergistic effect of these factors significantly enhances the optical performance and water stability of CsPbBr₃@MIL-53 nanocomposite phosphors. As a result, photoluminescence quantum yield (PLQY) of CsPbBr₃@MIL-53 nanocomposite phosphors reaches 75.4%, which is 2.3 times of that of solid-state CsPbBr₃ nanocrystal powders (33.2%). Even after being completely immersed in water for 10 h, its fluorescence intensity can still maintain 75.6% of the initial value. Finally, the green-emitting CsPbBr₃@MIL-53 nanocomposite phosphors were applied to white LED devices, achieving a wide-color-gamut coverage area of 126% NTSC and 85% Rec. 2020, which demonstrates its application prospects in wide-color-gamut display devices.

Phosphorus is one of the important elements in the ecosystem and plays a vital role in the process of life cycle. Inorganic phosphorus is a major form of phosphorus, usually in the form of phosphate ions. The rapid and efficient quantitative detection of phosphate ions has always been a hot research direction in the fields of clinical chemistry, pharmacology, biochemical analysis, industrial production and environmental pollution monitoring, but still facing some challenges in accuracy and convenient in some special circumstances. In present work, PAA-Ca(Ce) nanocluster fluorescent probes with good dispersibility and stability were synthesized by complexing with Ca²⁺ and Ce³⁺ using polyacrylic acid (PAA) as complexing agent. The reaction product between the probe and the phosphate ion was irradiated by 298 nm excitation light, and a linear graph was established based on the correlation between the peak intensity at the emission peak of 352 nm and the phosphate ion concentration. The experimental results show that the linear relation of the nanofluorescent probe with the (Ca²⁺+Ce³⁺) concentration of 37.575 mmol/L is y=1.09x+2.05, and the reliability range of fluorescence intensity is 13.5-66.91 mmol/L. Compared with molybdenum-antimony resistance spectrophotometry, this method has a higher recovery. The experimental results of inorganic phosphorus in rat serum verify the reliability of the method. The results above indicate that the fluorescence probe studied in this paper has good quantitative detection performance of phosphate.

Mechanoluminescent (ML) materials, due to their unique mechanical-to-optical energy conversion, hold significant promise in stress sensing and are poised to become the next generation of visual strain-sensing materials. Currently, expanding ML material systems and enhancing their performance remain focal points of research. In this study, a series of Tb³⁺-doped green ML phosphors was synthesized using BaSrGa₄O₈ matrix (hexagonal crystal system, space group P6₃, with a non-centrosymmetric structure) via high-temperature solid-state synthesis. These materials emitted bright green light under various mechanical excitations (tension, compression, and torsion). Clear note mappings were observed by writing B, S, G, O, T, and b on the prepared ML elastomer with a glass rod. By analyzing the colormap, the stress conditions during the writing process could be traced. This is the first observation of ML phenomenon in the above-mentioned matrix doping system. Under 254 nm ultraviolet (UV) excitation, BaSr_1-xGa₄O₈: xTb³⁺ phosphors exhibited bright green emission at 543 nm, which was attributed to ⁵D₄-⁷F₅ transition of Tb³⁺, and shared the same luminescent center as ML. The samples continued to display strong long persistent luminescence after UV irradiation was removed. By combining ML, photoluminescence (PL), and long persistent luminescence (LPL) with thermoluminescence (TL) analysis, further insights into their intrinsic connections were elucidated. In conclusion, this study broadens the range of high-performance ML material systems, showcasing potential applications in visual strain sensing, information security, and anti-counterfeiting.

Perovskite CsPbBr₃ quantum dots (PQDs) encapsulated within borosilicate glass can markedly improve their stability, expanding their applicability in sectors under lighting and display of light emitting diode (LED). However, this encapsulation has unintended consequence of reducing both the photoluminescence (PL) intensity and PL quantum yields (PLQY). This research aims to enhance the PL intensity of CsPbBr₃ perovskite quantum dots glass (PQDs@glass) by exploring the effects of thermal induction temperature and Pb²⁺ content on its structural properties. The results demonstrate that the optimal thermal induction temperature for maximizing PL intensity is 460 ℃, with a Pb²⁺ concentration of 6 mol. The study revealed that the increase in Pb²⁺ concentration led to the densification of the glass network structure and altered the diffusion behavior of glass components. This alteration affected the crystallization process of PQDs, which ultimately resulted in variations in the luminous intensity of PQDs@glass. This study achieved a highly desirable PLQY of 95.6% for PQDs@glass and successfully carried out size-controllable preparation of PQDs within a borosilicate glass matrix. Remarkably, the obtained results show that over 86% of the obtained PQDs particles fall within a narrow size range of 6-14 nm with average diameter of 10 nm, leading to a well-defined size distribution. Notably, these PQDs exhibit exceptional stability, as evidenced by their ability to retain an extraordinary 98.9% of the initial emission intensity following ten consecutive thermal cycles spanning from room temperature to 200 ℃. Finally, to verify its applicability in LED lighting and display, the obtained PQDs@glass powder was blended with polydimethylsiloxane (PDMS), yielding exemplary LED devices which exhibit an exceptional color gamut range surpassing 110% of the standard RGB (sRGB) color space. In conclusion, this study lays the groundwork for the scalable synthesis of PQDs@glass and paves the way for its utilization in the realm of LED device technology.

Hysteresis effect greatly impacted performance and stability of perovskite solar cells. Ion migration and the resulting accumulation of interface ions were widely recognized as the most important origins. In this study, upconversion luminescent nanoparticles (UCNP) were used to modify the interface of the electron transport layer/perovskite active layer and the intrinsic perovskite active layer, and the effects of UCNP on the morphology, structure, spectral/optoelectronic properties, and ion migration kinetics of perovskite were systematically explored. The results indicated that the device with UCNP modified perovskite active layer has the best photoelectric conversion efficiency (PCE, 16.27%) and significantly improves the hysteresis factor (HF, 0.05). Furthermore, circuit switching transient optoelectronic technology was employed to investigate the ion migration kinetics without interference from photo-generated carriers, revealing the dual role of UCNP in suppressing ion migration and accumulation during the optoelectronic conversion process of perovskite solar cells. On the one hand, UCNP formed barrier layers that hinder ion accumulation. On the other hand, UCNP infiltrated into grain boundaries of perovskite phase during annealing, hindering ion migration and reducing the recovery voltage from 0.43 V to 0.28 V. The mechanism of carriers and ions interaction was explained based on the polarization-induced trap state model to declare the process of UCNP suppressing the hysteresis of perovskite photovoltaic devices. This work provides effective solution for regulating the hysteresis of perovskite solar cells.