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The increasing demand for second near‐infrared (NIR‐II) region materials, which retain the advantage of minimal scattering and immense applications in the medical and NIR spectroscopy field, has led to considerable research in this region. A mini light‐emitting diode (mini‐LED) is essential for backlighting liquid crystal displays, indicating the need for the small size of phosphors. However, current market phosphors must be more significant to be a viable option for mini‐LEDs. This scenario necessitates the synthesis of small‐sized phosphors to be used in mini‐LEDs. In this work, a mesoporous silica nanoparticle (MSN) and incorporated the Mg1−yGa2−xO4:xCr3+,yNi2+ system is fabricated. The structural investigation confirmed the single phase of MgGa2O4 with a pore size of 2.73 nm for the MSN. The results showed a steady NIR‐II signal at 1270 nm and an enhanced energy transfer with a high quantum yield of 79.2% for a nanophosphor. The mini‐LED package revealed a 1000–1600 nm signal, qualifying the nanophosphor for realistic applications. This work can make provisions for various NIR‐II nanophosphors in the LED industry. [ABSTRACT FROM AUTHOR]

In modern technology devices, an energy‐saving miniature near‐infrared (NIR) light source plays a critical role in non‐destructive, non‐invasive sensing applications and further advancement of technology. This paper reports the broadband NIR luminescence of Cr3+ clusters for designing phosphor‐converted NIR light‐emitting diodes as an alternative to typical isolated Cr3+ centers and Cr3+ ion pairs. Here, Cr3+ clusters form in the intermediate spinel structure of MgGa2O4 by utilizing the long‐chain edge‐shared octahedral dimers with the shortest bond distance between Cr3+ cations. Electron paramagnetic and magnetometry measurements confirm the isolated Cr3+ and Cr3+ clusters, resulting in NIR luminescence with three distinct emission centers. The formation of Cr3+ clusters in MgGa2O4 ensures stable internal quantum efficiency (≈94%), full‐width‐half‐maximum (248 nm), thermal stability (87%), and a radiant flux of ≈17.66 mW. This work offers a promising approach to NIR phosphor design and enhances the understanding of luminescence mechanisms in spinel and related structures. [ABSTRACT FROM AUTHOR]

This paper analyzes the influence of pressure on electron–lattice interactions in the 5d excited states of Ce3+ and Eu2+ in the AlN host based on pressure-dependent photoluminescence and photoluminescence excitation spectra. High-pressure measurements on AlN samples doped with Eu2+ and Ce3+ ions reveal that the Stokes shift increases with pressure for Eu2+ dopants and decreases for Ce3+ dopants. Within the interstitial sites of AlN occupied by lanthanide dopants, the effect of crystal field strength on the behavior of luminescent ions can be strongly reduced. Therefore, the observed changes in optical properties under pressure can be interpreted as occurring mainly due to electron–lattice interactions. Based on the experimental data, one can conclude that the barycenter energy of Eu2+ exhibits virtually no pressure-induced shift (within the experimental error), unlike Ce3+, which shows a pressure-dependent redshift. Our findings demonstrate the significance of the specific central ion in the lattice relaxation process. [ABSTRACT FROM AUTHOR]

Applications in near‐infrared (NIR) have been explored significantly in many fields, including bioimaging, night vision, plant growth, and chemical analysis. Different emission profiles are required within the same industry. Developing luminescent materials with different tuning methods is reliable for controlling the NIR regions (NIR‐I, 700–1000 nm; NIR‐II, 1000–1700 nm). Spinel phosphors are promising candidates due to their ability to modulate the crystal field. Understanding the parameters that influence the degree of inversion in spinel compounds is crucial to harness the variability of the spinel structure. Cr3+ and Ni2+ are ideal activators for NIR‐I and NIR‐II emissions, respectively. However, there is a need for phosphors that emit in the NIR‐II region when excited by visible light. Although the energy transfer method combining two activators is considered, this review focuses on different types of spinel structures, discussing their types and common strategies to tune the host structure. The goal is to achieve desired shift and broadness of the entire NIR spectrum, highlighting the importance of spectrum tuning for practical applications. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots usually possess excellent optical properties, such as high color purity, high photoluminescence quantum yield, and tunable emission wavelength. However, their relatively low stability against heat, water, oxygen, and light hinders their practical applications in the field of optoelectronic devices. Herein, melt‐quenching and heat treatment crystallization methods are used to fabricate the CsPbBr3@glass. Atomic layer deposition and the sol–gel method are applied to encapsulate the CsPbBr3@glass with a dense SiO2 layer and hydrophobic SiO2 layer, respectively, to further improve the water resistance, thermal reversibility of photoluminescence, and photostability. The CsPbBr3@glass@ASG can be synthesized with the triple layer encapsulation of the glass matrix, dense SiO2 layer, and hydrophobic SiO2 layer. During the water resistance test for seven weeks, CsPbBr3@glass@ASG can preserve ≈100% of initial PL intensity. Similarly, it can preserve ≈100% of PL intensity after five continuous heating–cooling cycles between 30 and 100 °C. In addition, the internal and external quantum efficiencies of CsPbBr3@glass@ASG can still be maintained at 42.0% and 33.7%, respectively. Results indicate that CsPbBr3@glass@ASG can provide a balance between optical properties and extrinsic stability successfully, thereby becoming a potential candidate material for practical applications related to optoelectronic devices in the future. [ABSTRACT FROM AUTHOR]