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NaGdF4 was selected as the matrix material, and Er3+ and Yb3+ were used as doping elements, Er3+/Yb3+ doped NaGdF4 down-conversion luminescent materials were prepared by hydrothermal method, and characterized by XRD, SEM, emission spectroscopy, fluorescence attenuation analysis, etc. The results showed that the doping of Er3+/Yb3+ didn’t change the lattice structure of NaGdF4, and no new products were generated. The sample had good purity, with an average particle size between 50 and 60 nm. The sample was irradiated with 380 nm excitation light, and the emission spectra showed emission peaks of 699, 662, 563 and 554 nm, corresponding to the 4I9/2→4I15/2, 4F9/2→4I15/2, 4S3/2→4I15/2 and ²H11/2→4I15/2 energy level transitions of Er3+ ions, respectively. With the increase of Yb3+ doping concentration, the luminescence intensity in the near-infrared region showed a trend of first increasing and then decreasing. The CIE color coordinate indicated that the color of the sample gradually transitions from the yellow green region to the blue purple region. When n(Er3+)∶n(Yb3+)=2∶2, the emission spectral intensity of NaGdF4 luminescent material was the highest in the visible light region. The energy transfer efficiency and quantum efficiency continuously increased with the increased of Yb3+ concentration. When the concentration of Yb3+ reached 6 mol%, the minimum sample lifetime was 7.70 μs. At this doping concentration, NaGdF4 had the highest energy transfer efficiency and quantum efficiency, which were 81.19% and 181.19%, respectively. [ABSTRACT FROM AUTHOR]

Featured Application: Significant photoluminescence enhancement in Alq3 caused by Ag nanostructures makes it ideal to be applied in emissive layers of organic light emitting diodes. The continuous performance optimization of tris(8-hydroxyquinoline)aluminum (Alq3) materials is of great significance during the commercialization process of organic light-emitting diodes (OLEDs). In incorporating Ag nanostructures into Alq3, the photophysical properties are greatly improved by the plasmon–exciton coupling effect. Localized surface plasmons (LSPs) in Ag nanoparticles (NPs) efficiently increased the absorption ability. The coexistence of LSPs and propagating surface plasmons (PSPs) in Ag nanowires (NWs) leads to a PL enhancement of 5.3-fold and a full-width at half maximum (FWHM) narrowed by 10 nm. Temperature-dependent PL measurements exhibit that the plasmonic density of states (DOS) increases with decreasing temperature below 40 °C, and the thermal exchange can be accelerated by the introduction of Ag nanostructures. Effective suppression of the thermal accumulation effect is further proved by excitation intensity (EI)-dependent PL measurements. We also found that Ag nanostructures could mainly change the y coordinates in International Commission on Illumination (CIE), leading to a higher brightness. The 5372 K color temperature of an Ag NWs-embedded composite is suitable for daylight-type fluorescent OLEDs. The results would pave an effective way for further optimizing the optical performance of light-emitting materials in OLEDs. [ABSTRACT FROM AUTHOR]

• Focus on toxicity and instability issues of lead halide perovskites. • Discus the current strategies to address stability for commercial WLED applications. • Discuss the efficiency, stability, and scalability challenges for WLEDs in perovskites. Lead halide perovskites possess exceptional optical and electrical properties, yet their inherent toxicity and instability present significant challenges for practical application in white light-emitting diodes (WLEDs) for displays and lighting. Alhough, techniques such as reduced dimensionality, transition metal doping, and protective encapsulation have shown some success in enhancing stability. These advancements remain limited and do not fully meet the requirements for real-world WLED devices. This featured letter delves into the emerging advancements in lead-free halide perovskite WLEDs includes color-conversion WLEDs, and single-emissive-layer WLEDs. Despite significant advancements, issues with stability, efficiency, and scalable fabrication still exist. Future approaches centre on methods to enhance these features, opening the door for lead-free perovskite WLEDs to become commercially viable and bringing in a new age of environmentally friendly lighting options. Additionally, this featured letter provides a comprehensive review of the current advancements and future possibilities in WLEDs based on lead-free halide perovskites materials. This letter serves as an invaluable resource for researchers, scientists, and engineers dedicated to advancing this field. [ABSTRACT FROM AUTHOR]

The continuous performance optimization of tris(8-hydroxyquinoline)aluminum (Alq3) materials is of great significance during the commercialization process of organic light-emitting diodes (OLEDs). In incorporating Ag nanostructures into Alq3, the photophysical properties are greatly improved by the plasmon–exciton coupling effect. Localized surface plasmons (LSPs) in Ag nanoparticles (NPs) efficiently increased the absorption ability. The coexistence of LSPs and propagating surface plasmons (PSPs) in Ag nanowires (NWs) leads to a PL enhancement of 5.3-fold and a full-width at half maximum (FWHM) narrowed by 10 nm. Temperature-dependent PL measurements exhibit that the plasmonic density of states (DOS) increases with decreasing temperature below 40 °C, and the thermal exchange can be accelerated by the introduction of Ag nanostructures. Effective suppression of the thermal accumulation effect is further proved by excitation intensity (EI)-dependent PL measurements. We also found that Ag nanostructures could mainly change the y coordinates in International Commission on Illumination (CIE), leading to a higher brightness. The 5372 K color temperature of an Ag NWs-embedded composite is suitable for daylight-type fluorescent OLEDs. The results would pave an effective way for further optimizing the optical performance of light-emitting materials in OLEDs.