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Distinctive luminescent properties and excellent stability of long persistent luminescent (LPL) glass‐ceramic hold promise for anti‐counterfeiting and encryption applications. However, rational synthesis and a deep understanding of the precipitation of dual‐phase microcrystals in glass substrate to improve the encryption level remain challenging. Here, we carefully designed the components based on the phase diagram and combined them with the glass‐forming region. By utilizing the different crystallization behaviors of SrAl2O4 and CaAl2O4 in the glass matrix to realize dual crystals coexistence in a borate glass matrix, which provides different crystal field environments for Eu2+ luminescence, thus obtaining excitation‐dependent tunable LPL characteristics in a single sample. Mechanism studies unveiled that this excitation‐dependent behavior arises from the differential capture of charge carriers by defect oxygen vacancies in the sample when charged with different laser sources, providing a channel for multimode anti‐counterfeiting encryption. This strategy of constructing a double crystal field in a glass matrix overcomes the stringent requirements of a single heat treatment method for the crystallization temperature of biphasic crystals, which could become a stable and promising advanced anti‐counterfeiting encryption material and provide new insights into the multi‐band luminescence regulation of rare earth ions. [ABSTRACT FROM AUTHOR]

Mn4+‐activated red‐light fluorides are widely used in high‐quality displays, due to the narrow‐spectral emission. However, achieving exceptional chromaticity coordinates and appropriate quantum efficiency (QE) at the same time is a great challenge. Herein, a Li substitution strategy is proposed for enhancing QE and improving the thermal stability of red‐light Mn4+‐activated Cs2NaGaF6 (CNGF). The external quantum efficiency (EQE) of optimal Cs2NaGaF6: Mn4+, Li+ (CNGF: Mn4+, Li+) is improved from 15.79% to 33.61% and thermal stability increases from 68.4% to 85.5% (intensity at 150 °C relative to room temperature). EQE enhancement mechanism on the strategy is explored that Li substitution increases the local structural distortion of Mn4+ for relieving the parity forbidden, and promotes Mn4+ doping in the host lattice, which provides new insights for improving the QE of Mn4+ non‐equivalent doped fluorides. Moreover, with exceptional chromaticity coordinates of (0.7029, 0.2970), optimal sample CNGF: 4.8 mol% Mn4+,0.9 mol% Li+ can be used to fabricate white light‐emitting diode (w‐LED) backlight, which obtains wide color gamut of 110.68% National Television Standards Committee (NTSC) and high luminous efficacy of 110.57 lm W−1, indicating that CNGF: Mn4+, Li+ is a promising candidate for the next generation of wide gamut and efficient displays. [ABSTRACT FROM AUTHOR]

As an environment‐friendly powder with good coloring performance, rare earth sulfide is one kind of the important choices to replace cadmium and lead colorants. In particular, γ‐Ce2S3 belongs to rare earth sesquisulfide, which has a bright red color. However, the uncoated γ‐Ce2S3 is easy to decompose and release H2S in a humid or acidic environment, and its air thermal stability is limited to 350°C. In this work, γ‐Ce2S3 powders coated with zinc oxide were prepared by heterogeneous precipitation method, and a dense protective layer was formed by ZnO to improve chemical and thermal stability. Moreover, silicon dioxide was deposited on the surface of the zinc oxide coating using the microemulsion process to strengthen the powder's acid resistance. The double shells structure greatly promoted thermal stability and acid resistance of γ‐Ce2S3 powders. The results showed that rare earth sulfide powders with double shells have good stability for coloring applications. [ABSTRACT FROM AUTHOR]

Mn4+‐activated fluorides with a saturated red color and sharp line emission are ideal for applications in the light‐emitting diodes (LEDs) backlight for displays. However, the emissions attributed to 2E→4A2 parity and spin‐forbidden transitions limit the design and adjustments of emission wavelength and chromaticity coordinates. Herein, machine learning algorithms are used to build a wavelength‐prediction model for Mn4+‐activated fluorides. The model precisely identifies the key structural features that affect wavelengths and discovers target materials. The predicted candidate Cs2NaAlF6:Mn4+ (CNAF) with a long‐wavelength zero‐phonon‐line emission at 628 nm exhibits a redshift in comparison with other reported Mn4+‐activated fluorides and commercial K2SiF6:Mn4+, but maintains narrow spectral emission with full‐width half maximum (FWHM) of 11.2 nm. The redshift and narrow spectra result in a color purity of 99.7% and Commission Internationale de L'Eclairage (CIE) chromaticity coordinate of (0.7032,0.2967) that is close to the pure red‐light point of Recommendation BT. 2020 (Rec. 2020). Moreover, CNAF is prepared as a transparent red‐light film, and the device fabricated using the blue‐light mini‐LEDs, green quantum‐dot film, and CNAF film exhibits a wide color‐gamut of 121.5% National Television Standards Committee (NTSC) or 90.6% Rec. 2020, suggesting that CNAF has potential for wide‐color‐gamut displays. [ABSTRACT FROM AUTHOR]

The persistent photoconductive behavior caused by traps in the active materials usually weakens the sensitivity and stability of photodetectors. Herein, tellurium (Te) microwire and polyvinyl alcohol (PVA) composites were developed as functional flexible substrates to improve the near-infrared (NIR) photoresponse performance of MoS2:Er-based devices with the metal–semiconductor–metal structure. The flexible photodetector exhibits a rise/fall time of ∼2.9–3.1 ms, a responsivity of ∼0.28 mA W−1, and a detectivity of ∼1.41 × 1010 Jones under 808 nm irradiation. The enhanced mechanism can be attributed to the charge transfer between Te microwires and MoS2:Er films, which suppresses the dark current of the device and optimizes the generation process of electron–hole pairs under light illumination. Meanwhile, the flexibility of the device allows it to be employed in human heart rate monitoring. This work offers a simple and essential strategy for constructing integrated flexible NIR photodetectors with high performance. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) emission phosphors are crucial for the construction of next‐generation smart lighting sources; however, the thermal quenching (TQ) issue poses a significant challenge to their applications. In this study, anti‐TQ NIR emission is demonstrated in hexafluoride phosphors, using a facile Cr3+/Fe3+ co‐doping strategy. Owing to the controlled forward resonance energy transfer (ET) from Cr3+ to Fe3+ and one‐phonon‐assisted back ET from Fe3+ to Cr3+, the thermally enhanced broadband NIR luminescence is realised in series of fluoride such as Na3FeF6:Cr3+, Na3GaF6:Cr3+, Fe3+, K2NaScF6:Cr3+, Fe3+, etc. By varying the chemical composition of the phosphor, the anti‐TQ emission is achieved even upon raising the temperature to ≈423 K. The anti‐TQ luminescence mechanism is investigated, and the ET offset effect on luminescence TQ is demonstrated. More importantly, by combining these phosphors with blue InGaN chip, anti‐/zero‐TQ NIR light emitting diodes with a high photoelectric conversion efficiency even up to 19.13%@20 mA are further fabricated to realize the emerging coded optical wireless‐communication applications. These findings can initiate the exploration of NIR phosphors with anti‐TQ luminescence properties for advanced optoelectronic applications. [ABSTRACT FROM AUTHOR]

Broadband short-wave near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have been attracting keen interest for miniature NIR spectroscopy, while still lacking sufficient novel broadband NIR-emitting phosphors. Herein, we report a novel MgNb2O6:Cr3+ polycrystalline phosphor with a broad NIR emission band centered at 970 nm and a large full-width at half-maximum of approximately 155 nm under excitation of bluish-green light at around 515 nm. The optimized phosphor MgNb2O6:1%Cr3+ features a high internal quantum efficiency (IQE) of ∼85.5% and a moderate external QE of 25.2%. The fluorescence properties determined by two distorted hexa-coordination octahedral sites (i.e. [MgO6] and [NbO6]), low crystal field strength (Dq/B ∼ 1.65), and Cr3+-doping concentration were systematically investigated for comprehensive understanding of photophysical mechanisms. Besides, this broadband NIR phosphor MgNb2O6:Cr3+ exhibits a moderate thermal quenching of 21.4%@373 K for pc-LED application. An NIR pc-LED self-built by combining the optimal phosphor with a commercial cyan of ∼515 nm exhibits an NIR output power increase from 3.19 to 11.38 mW as the drive current is varied from 40 to 220 mA. With the help of this prototype pc-LED device, multiple applications were successfully performed to clearly recognize blood vessel distributions in the human finger, penetrate a plastic cap, and distinguish multi-color text. Undoubtedly, further development of such broadband short-wave NIR-emitting phosphors will make novel pc-LED devices for significant applications in biomedical imaging, nondestructive safety detection, intelligent identification, etc. [ABSTRACT FROM AUTHOR]

The development of highly efficient near infrared (NIR) luminescence materials is crucial for advancing the next generation compact light sources. However, the realization of target material with emission in the NIR-II spectral region (1000–1700 nm) remains a major challenge. Herein, a NIR-II emission phosphor Ba3BPO7:Mn5+ peaking at 1176 nm with a full width of half maximum of 22 nm is demonstrated via a selective site occupancy engineering strategy. Upon 660 nm red-light excitation, high internal quantum efficiency of 50.6% and external quantum efficiency of 30.5% are obtained in this phosphor. Density functional theory calculations and structural analyses provide an understanding of stabilizing pentavalent manganese in Ba3BPO7:Mn5+. The highly efficient NIR-II emission is mainly ascribed to the relatively high distorted tetrahedral crystal field environment of Mn5+ in this system and the stable valence state. Combining this phosphor with 660 nm red-light chip, we fabricate a light emitting diode with NIR-II output power of 19.2 mW@300 mA, which shows promising applications in anti-counterfeiting, special information identification, etc. This work provides some important insights into the design of highly efficient Mn5+ based NIR-II emission and the emerging applications. [ABSTRACT FROM AUTHOR]

The development of highly efficient near infrared (NIR) luminescence materials is crucial for advancing the next generation compact light sources. However, the realization of target material with emission in the NIR-II spectral region (1000–1700 nm) remains a major challenge. Herein, a NIR-II emission phosphor Ba3BPO7:Mn5+ peaking at 1176 nm with a full width of half maximum of 22 nm is demonstrated via a selective site occupancy engineering strategy. Upon 660 nm red-light excitation, high internal quantum efficiency of 50.6% and external quantum efficiency of 30.5% are obtained in this phosphor. Density functional theory calculations and structural analyses provide an understanding of stabilizing pentavalent manganese in Ba3BPO7:Mn5+. The highly efficient NIR-II emission is mainly ascribed to the relatively high distorted tetrahedral crystal field environment of Mn5+ in this system and the stable valence state. Combining this phosphor with 660 nm red-light chip, we fabricate a light emitting diode with NIR-II output power of 19.2 mW@300 mA, which shows promising applications in anti-counterfeiting, special information identification, etc. This work provides some important insights into the design of highly efficient Mn5+ based NIR-II emission and the emerging applications. [ABSTRACT FROM AUTHOR]

Flexible sensors have attracted extensive research interest due to their great application potential in biodetection, flexible display, and wearable devices. However, they still have a lot of room for improvement in terms of luminous color, flexibility, and self‐powered systems. A wearable, antifreeze, and discoloration sensing system based on electroluminescence, mechanoluminescence, and tribo‐power generation is developed in this paper. Triboelectric nanogenerator systems can harvest biomechanical energy from hand clapping and knee/elbow bending to generate real‐time electrical signals. The use of dielectric materials reduces the initial voltage and frequency of light‐emitting devices, enabling them to be driven by Triboelectric nanogenerators. At the same time, the device can produce red, blue, white, and other multicolor light. In addition, the system can produce an optical signal output due to external mechanical stimulation. As a result, the sensor system is simple to manufacture and unique to operate, proving its potential applications in areas such as cold‐resistant displays, wearable optoelectronics, soft robotics, and electronic skin. [ABSTRACT FROM AUTHOR]

Owing to the avoidance of device reabsorption and improvement in the color rendering index (CRI), Mn4+‐activated fluorides have potential applications in full‐spectrum lighting. However, it is still challenging to improve the external quantum efficiency (EQE) and adapt it to the excitation of violet‐light chips used for increasing the CRI and reducing the blue‐light hazard. Here, red‐light single crystals Rb2Si1−xMnxF6 (RSMF) with an ultrahigh optimal Mn4+ content of 32.4 mol% are obtained through structural and morphological design. Breaking through the limitation of low quenching concentration (<10 mol%) of Mn4+‐activated fluorides, the as‐grown heavy Mn4+‐doped RSMF crystal not only exhibits a record EQE of 80.2% but also has a broad excitation band of full width at half maxima = 86 nm, which can be efficiently excited by both blue (460 nm) and violet (437 nm) light. The white light‐emitting diodes fabricated by violet/blue dual‐chips, commercial green phosphor, and the optimized RSMF crystal can realize a high luminous efficacy of 161.8 lm W−1 and high CRI of Ra = 95.5. Additionally, laser diode devices with high luminous flux of 198.2 lm are also presented. This study provides new insights into heavy Mn4+‐doped materials and promotes the application of full‐spectrum lighting. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) is a promising two-dimensional material for optoelectronic applications owing to its strong light–matter interactions, high carrier mobility, and ability to combine with other materials. However, the intrinsic bandgap (1.3–1.8 eV) of MoS2 limits its applications in the near-infrared (NIR) region. Herein, a heterojunction NIR photodetector based on the Er-doped MoS2 film is developed. The photodetector presents self-powered NIR response with a fast rise/fall time of ∼9.2 μs/∼168 μs and a high detectivity of ∼3.25 × 1010 Jones at 980 nm. The high performance of the device is attributed to the improved separation of the photogenerated electron–hole pairs and the characteristic trapping capacity induced by Er dopants. Density functional theory calculations reveal that Er-doping introduces an additional energy level in the forbidden band of the MoS2:Er, and the Er-f electron orbital locates near its Fermi energy level, both of which contribute to the formation of photogenerated carriers. The MoS2:Er-based device with a 3-dB bandwidth of 5.4 kHz exhibits promising application potential in the NIR photo-communication field. Moreover, the laser calibration application of the high-performance photodetector is demonstrated. This work not only develops an effective strategy to enhance the NIR photoresponse of MoS2 films but also extends the application of MoS2-based devices. [ABSTRACT FROM AUTHOR]

Defects are a double‐edged sword for heterovalent metal‐ion doping phosphors. Along with the luminescence tunability of phosphors bestowed by defects, their expected luminescence efficiency would also be inevitably lowered due to the presence of these quenching sites. Herein, a chemical group substitution strategy is proposed, where inorganic polyhedrons act as the smallest chemical units during the structural evolution of the doping process. Such a method can not only effectively prevent the defect generation for charge compensation in heterovalent doping systems, but also facilitate the incorporation of activators into the matrix, leading to extremely high luminescence efficiency. The concept is first confirmed energetically favorable by first‐principles simulations. As a robust experimental proof, two newly reported Mn4+‐incorporated hexavalent organic‐inorganic hybrid oxyfluorides (TMA)2BO2F4:Mn4+ (where TMA stands for tetramethylammonium, and B = W6+ or Mo6+) present high quantum efficiency (up to 94.4%) and short lifetime (down to 2.26 ms) that are superior to the commercial red phosphor K2SiF6:Mn4+ (≈84.8%, ≈8.06 ms). Utilizing the differences in decay lifetimes and thermal quenching behaviors of (TMA)2BO2F4:Mn4+ and K2SiF6:Mn4+, a time‐ and temperature‐resolved single‐color multiplexing mode with high‐safety and easy‐access is developed for information security. This work offers an effective strategy to manipulate defect generation in luminescent materials. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) phosphors have recently received considerable attention in spectroscopy technology fields, but designing inexpensive, emission peaks centered above 800 nm, and multimodal broadband NIR luminescence material still remains a great challenge. Here, by selecting stannate compound Mg2SnO4 (MSO) as the host, a kind of broadband NIR phosphor MSO:Cr3+ with multimode luminescence properties is reported. The designed material exhibits an emission peaking at 800 nm and a full‐width at half maximum of 180 nm (≈2730 cm−1). The site occupation of Cr3+ in MSO is unraveled by density functional theory calculation. The constructed NIR light‐emitting device based on MSO:Cr3+ displays a high NIR output power of 187.19 mW@100 mA and remarkable photoelectric efficiency of 13.67%, and its multifunctional applications in information encryption, non‐destructive detection, and so on are also demonstrated. Additionally, through defect site reconstruction, MSO:Cr3+ presents superior broadband NIR persistent luminescence (PersL) properties with PersL duration time longer than 50 h. This work provides a feasible strategy to develop intelligent optical material integrated with multimodal luminescence through low‐cost stannate compounds as the host toward versatile applications such as non‐destructive detection and bioimaging. [ABSTRACT FROM AUTHOR]