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The advancement of Eu2+‐activated luminescent materials tailored to exhibit a range of properties is crucial for addressing the specific demands of various application fields. However, the lack of suitable lattice sites in numerous compounds for stable Eu2+ incorporation restricts their potential for diverse optical properties. Herein, a facile strategy of carbon and hydrogen coreduction utilizing graphite crucibles is proposed to effectively achieve the impressive luminescence of Eu2+ at trivalent Y sites in Rb3Y(PO4)2:Eu phosphors. Rb3Y(PO4)2:Eu exhibits blue‐violet emission when Eu2+ predominantly occupies the Rb1 and Rb2 sites. Inspiringly, by facilitating the reduction of more Eu3+ to Eu2+, a yellow emission band at 550 nm arising from Eu2+ at Y sites emerges, enabling the realization of single‐component white‐emitting and yellow‐emitting Rb3Y(PO4)2:Eu phosphors. The diverse luminescent properties of Rb3Y(PO4)2:Eu expand its potential applications in different white light source devices and optical thermometry. This work presents an innovative synthetic strategy to develop remarkable Eu2+ luminescence at trivalent cation sites, thereby broadening the optical properties of the material and enabling multifunctional applications. [ABSTRACT FROM AUTHOR]

Laser-based solid-state lighting is the future of the high-brightness lighting and long-distance automobile illumination industry. It has started replacing light-emitting diode (LED)-based lighting equipment with high thermal stabilities and transparencies, i.e., phosphor in glass (PiG). PiGs have received special attention because of their simple fabrication process and easy colour tuning. The study of glass is usually conducted in the field of phosphor fabrication, with very limited studies on its recycling. We demonstrated the utilization of rejected glass from other sources due to scratches, cracks and defects by some other means by recycling with the development of PiGs. The waste glass slides were crushed into fine powders, and the pulverized samples were sieved to an average particle size of 30 μm. Fine glass frits were mixed with Ce-doped Y3Al5O12 and sintered at 730°C for 30 min to refabricate glass as a PiG to overcome the recycling route for waste glass. A prototype design of laser-driven PiGs (LD-PiGs) has been developed for white light generation. Different concentrations of YAG:Ce (20–50%) in fine glass frits had colour rendering indices (CRIs) >60. The 25 wt.% YAG:Ce-developed PiG pellet showed better results than the other compositions in terms of photoluminescence emission intensity, CRI 69, colour-correlated temperature 5566 K and colour coordinates (0.331, 0.3328). PiG pellets are much better than YAG:Ce and UV-adhesive matrix screens printed on glass substrates used as white light sources. LD-PiGs exhibit superior thermal robustness. [ABSTRACT FROM AUTHOR]

Eu3+‐activated red‐emitting inorganic phosphors have been favored highly for their classical 5D0→7FJ (J = 0, 1, 2, 3, 4) emissions. However, the fatal drawbacks of poor luminous efficacy and weak 5D0→7F4 transition persist, resulting in the ongoing challenge of achieving far‐red emission. This research reports series of highly efficient far‐red phosphors LnTeBO5 (Ln = La3+, Y3+, Gd3+):Eu3+ with anomalously strong 5D0→7F4 transition, resulting from the distorted square antiprism [Ln/EuO8]. Both the luminous efficacy and thermal stability can be greatly enhanced via the simple composition variation. [Ln/EuO8] square antiprism‐triggered 5D0→7F2,4 transitions are elucidated in depth, acquiring ultra‐high luminous efficacy (IQE = 95%, EQE = 40%, and AE = 42%) and near‐zero thermal quenching (99%@150°C and 98%@200°C). Subsequently, the versatile utilizations in indoor lighting, plant growth lighting, and security ink are illustrated. This finding establishes a deep understanding for constructing high‐quality far‐red phosphors via the Eu3+‐centered structural units of square antiprism. [ABSTRACT FROM AUTHOR]

This paper reports white solid-state lighting potential of gold nanoparticles-embedded Dy3+-doped Li2CO3–SrO–ZnO–B2O3 glasses prepared using melt quenching. The produced materials undergo characterizations using various instrumentations to assess the sensitivity of changing AuNP concentrations on their emission characteristics. XRD phase analysis established that the samples were glasses. TEM analysis shows AuNPs, whereas EDX spectroscopic analysis confirmed the inclusion of precursor elements into the glasses. The thermal stability, Hruby parameter, and glass-forming ability are 146–156 °C, 1.27–1.39 and 66–0.65 respectively. The optical absorption spectra of the glasses are consistent with Dy3+ transitions, while the surface plasmon resonance band fits the AuNPs characteristics band. The emission spectroscopic analysis reveals intensification factors of 1.52, 1.84, and 1.14 for 6H15/2, 6H13/2, and 6H11/2 transitions. The Judd–Ofelt evaluation was made to support the experimental spectroscopic data. The CIE coordinates were traced to cool white color field with purity of 15.64–7.79% and CCT values of 5491–5437 K. The achieved excellent thermal properties, enhanced emission, and colorimetric properties, including color purity and natural daylight (cool) correlated color temperature (CCT) values, are advantageous for white solid-state lighting applications. [ABSTRACT FROM AUTHOR]

Tetrahedron‐based nitrides offer a wide range of properties and applications. Highly condensed nitridophosphates are examples of nitrides that exhibit fascinating luminescence properties when doped with Eu2+, making them appealing for industrial applications. Here, we present the first nitridomagnesophosphate solid solution series Ba3−xSrx[Mg2P10N20] : Eu2+ (x=0–3), synthesized by a high‐pressure high‐temperature approach using the multianvil technique (3 GPa, 1400 °C). Starting from the binary nitrides P3N5 and Mg3N2 and the respective alkaline earth azides, we incorporate Mg into the P/N framework to increase the degree of condensation κ to 0.6, the highest observed value for alkaline earth nitridophosphates. The crystal structure was elucidated by single‐crystal X‐ray diffraction, powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), and solid‐state NMR. DFT calculations were performed on the title compounds and other related highly condensed nitridophosphates to investigate the influence of Mg in the P/N network. Eu2+‐doped samples of the solid solution series show a tunable narrow‐band emission from cyan to green (492–515 nm), which is attributed to the preferred doping of a single crystallographic site. Experimental confirmation of this assumption was provided by overdoping experiments and STEM‐HAADF studies on the series as well on the stoichiometric compound Ba2Eu[Mg2P10N20] with additional atomic resolution energy‐dispersive X‐ray spectroscopy (EDX) mapping. [ABSTRACT FROM AUTHOR]

Over the past few years, light‐emitting diodes (LEDs) have emerged as an efficient replacement for standard incandescent and fluorescent lamps, due to their superior efficiency, energy conservation, service longevity, reliability, and affordability. However, identifying a red emitter for white LEDs has presented significant challenges. This study seeks to synthesize and analyze a novel red emitter, investigating its potential use in white LEDs and indoor plant growth lighting. The Sr2Lu(Nb,Mn)O6 is manufactured employing the traditional high‐temperature solid‐phase method. The internal and external quantum efficiencies (IQE and EQE) of double perovskites reached 32.39% and 21.67%. The g value calculates to 2.146, which corroborates that the magnetic dipolar transitions of Mn4+ ions inhabit symmetric octahedral sites. First‐principles investigations are utilized to unveil local electronic structures. Emission spectra reveal a substantial broad red emission peak at 688 nm. The Tanabe–Sugano diagram is applied to understand the luminescence mechanism. Additionally, the evaluation of parameters such as the internal UV emission ratio, crystal field strength, and Racah parameters is conducted. The luminescent intensity of the Sr2Lu(Nb,Mn)O6 can still be maintained at 60% upon reaching a temperature of 423 K. The findings suggest that Sr2Lu(Nb,Mn)O6 offers a novel alternative for white LEDs and indoor plant growth lighting. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis, structural, thermal and luminescence properties of Sr1−xZrSi2O7:xEu3+ (x = 0.01 ≤ x ≤ 0.05 mol) phosphors by solid-state reaction method in air. The optimal Eu3+ ion concentration in Sr1−xZrSi2O7:xEu3+ phosphor is 0.04 mol. The monoclinic crystal structure with P21/c space group was confirmed by the powder X-ray diffractometry (PXRD) technique. Thermal behavior of the present phosphors was investigated which shows better characteristics. Under 396 nm excitation, Eu3+ ions activated Sr1−xZrSi2O7 phosphors exhibited a strong red emission centered at 617 nm due to the f–f transition of 5D0 → 7F2 transition. The critical doping concentration of Eu3+ ion was x = 0.04 mol and the critical distance was determined as 19.1117 Å. The energy transfer among Eu3+ ions in Sr1−xZrSi2O7 phosphors was found to be a dipole–dipole interaction. Consequently, optimal phosphor shows a thermal stability up to 420 K, superior to that in analogous reports. And the quantum efficiency of prepared Sr1−xZrSi2O7:xEu3+ phosphor with 396 nm excitation was calculated to be nearly 72%. The photometric results indicate that the synthesized Orange-Red phosphor can be potentially applicable for solid-state lighting and display devices applications. [ABSTRACT FROM AUTHOR]

CaTiO3:xEr3+ (0.1≤x≤7 mole%) phosphor materials were meticulously prepared through the solution combustion method. Comprehensive analyses employing Powder X-ray Diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infrared Spectroscopy (FTIR) were conducted to investigate the phase, morphology, and vibrational characteristics of the synthesized phosphors. A detailed luminescence study was undertaken using photoluminescence spectroscopy, revealing distinctive 4f-4f transitions associated with Er3+ in both excitation and emission spectra. The application of Dexter's theory provided insights into the quenching mechanism inherent in CaTiO3:Er3+ phosphors. Photometric studies were carried out to evaluate the suitability of the synthesized material for solid-state lighting applications. Furthermore, to assess the thermal stability of the phosphor material, the activation energy was computed. The fluorescence intensity ratio of thermally coupled energy levels of Er3+ ion was utilized to assess the temperature-sensing capabilities of the synthesized material. This material may be suitable for solid-state lighting and optical thermometry applications.

High‐pressure chemistry has provided a huge boost to the development of scientific community. Pressure‐induced emission (PIE) in halide perovskites is gradually showing its unique charm in both pressure sensing and optoelectronic device applications. Moreover, the PIE retention of halide perovskites under ambient conditions is of great commercial value. Herein, we mainly focus on the potential applications of PIE and PIE retention in metal halide perovskites for scintillators and solid‐state lighting. Based on the performance requirements of scintillator and single‐component white light‐emitting diodes (WLEDs), the significance of PIE and PIE retention is critically clarified, aiming to design and synthesize materials used for high‐performance optoelectronic devices. This perspective not only demonstrates promising applications of PIE in the fields of scintillators and WLEDs, but also provides potential applications in display imaging and anti‐counterfeiting of PIE materials. Furthermore, solving the scientific disputes that exist under ambient conditions is also simply discussed as an outlook by introducing high‐pressure dimension to produce PIE. [ABSTRACT FROM AUTHOR]

The wet chemical synthesis was used to make a series of Sr3La(PO4)3:Eu3+ phosphors. X-ray diffraction (XRD), morphology, photoluminescence characteristics and chromaticity were thoroughly investigated. The X-ray diffraction was used to confirm the cubic phase with the space group I − 4 3 d (220). The Sr3La(PO4)3:Eu3+ phosphors show a strong excitation peak at 394 nm. Upon 394 nm excitation, two emission peaks were observed at 594 nm (orange) and 615 nm (red), which corresponding to the transitions 5D0 → 7F1 and 5D0 → 7F2 of Eu3+ ions, respectively. The concentration quenching occurred at 0.5 mol % of Eu3+ ions. The chromaticity coordinates of wavelength 594 nm are (x = 0.597, y = 0.401), and wavelength 615 nm is (x = 0.680, y = 0.319). The Sr3La(PO4)3:Eu3+ phosphors are a series of candidate phosphors for near-UV-based solid-state lighting. [ABSTRACT FROM AUTHOR]

In this work, an empirically derived multi-domain model of a light-emitting diode (LED) luminaire is proposed. The optical, electrical, and thermal characteristics of LEDs are obtained from the data sheets provided by manufacturers. Both transient and steady-state performance of LED luminaire were realized theoretically and validated against experimental findings from earlier investigations. The difficulties encountered in creating an ideal LED luminaire are discoursed and examined. Most of the studies on LED luminaires described in prior works ignored the influence of luminaire housing and optics on the thermal management of the luminaire. Knowledge of thermal time constants of LED luminaires is important, as they decide the rate of luminous flux decay when LED lighting systems are used for long periods of operation. Thermal time constants also decide the time taken by the LED junction to reach steady state with its surrounding. From the study it is inferred that the increase in junction temperature and deterioration of luminous flux is controlled by the product of the single most dominant thermal resistance from the junction to a point along the heat conduction path and sum of all the downstream thermal capacitances. This is true as in most cases LED device thermal capacitance is very less related to the thermal capacitance of the heat-sink, hence the product of single most dominant thermal resistance and thermal capacitance of heat-sink decide the rate of rising of junction temperature or luminous flux deterioration. [ABSTRACT FROM AUTHOR]

For ecologically friendly and energy-efficient solid-state light sources, phosphors with low color-correlated temperatures (CCTs) and high color rendering indices (CRIs) are greatly desired. Herein, a co-precipitation method is used to modulate the fluorescence color of ZnO nano- material for bright multi-color light emitting diodes (LEDs) applications. The structural, thermal, morphological and optical properties of ZnO nanomaterials have been studied. Thermogravimetric analysis (TGA) of the as-synthesized nanomaterials reveals their good thermal stability whereas XPS analysis confirms their chemical states. We demonstrate that after combining ZnO with Ag2O and MnO2, the nanocomposite can attain extraordinary luminous tunability as realized by the photoluminescence (PL) properties of the nanomaterials. The estimated Commission Internationale de l'Eclairage (CIE) color coordinates indicate that ZnO, the blue color phosphor can be tuned to orange-red color phosphor (ZnO/Ag2O and ZnO/MnO 2) and to white color phosphor (ZnO/Ag2O/MnO 2) exhibits fairish color rendering index (CRI) of 84, after composited with Ag2O and MnO2. Finally, the ZnO/Ag2O, ZnO/MnO2 and ZnO/Ag2O/MnO2 nanocomposites have the potential to be utilized as phosphor materials in warm white LED applications because of their extremely pure, robust stability and tunable emission colors. Our findings can be used as a new benchmark for the identification of new phosphors and the tunability of their luminescent color for solid-state lighting applications. In this study, it can be observed that photoluminescence emission of ZnO nanostructure can be tuned after composited with Ag2O and MnO2. The tunability can be represented by Commission Internationale d'Eclairage (CIE) chromaticity diagram. From CIE diagram, it can be seen that photoluminescent colors acquired by ZnO nanostructures can be enhanced after composited with Ag2O and MnO2, and therefore making them suitable candidate to be used in warm white light LED applications. [ABSTRACT FROM AUTHOR]

Solid-state lighting (SSL) devices are ubiquitous in several markets, including architectural, automotive, healthcare, heritage conservation, and entertainment lighting. Fine control of the LED light output is crucial for applications where spectral precision is required, but dimming LEDs can cause a nonlinear response in its output, shifting the chromaticity. The nonlinear response of a multi-color LEDs can be corrected by curve-fitting the measured data to input dimming controls. In this study, the spectral output of an RGB LED projector was corrected using polynomial curve fitting. The accuracy of four different measurement methods was compared in order to find the optimal correction approach in terms of the time and effort needed to perform measurements. The results suggest that the curve fitting of very high-resolution dimming steps (n = 125) significantly decreased the chromaticity shifts between measured (actual) and corrected spectra. The effect size between approaches indicates that the curve-fitting of the high-resolution approach (n = 23) performs equally well as at very high resolution (n = 125). The curve-fitting correction can be used as an alternative approach or in addition to existing methods, such as the closed-loop correction. The curve fitting method can be applied to any tunable multi-color LED lighting system to correct the nonlinear dimming response. [ABSTRACT FROM AUTHOR]

Abstract High‐pressure chemistry has provided a huge boost to the development of scientific community. Pressure‐induced emission (PIE) in halide perovskites is gradually showing its unique charm in both pressure sensing and optoelectronic device applications. Moreover, the PIE retention of halide perovskites under ambient conditions is of great commercial value. Herein, we mainly focus on the potential applications of PIE and PIE retention in metal halide perovskites for scintillators and solid‐state lighting. Based on the performance requirements of scintillator and single‐component white light‐emitting diodes (WLEDs), the significance of PIE and PIE retention is critically clarified, aiming to design and synthesize materials used for high‐performance optoelectronic devices. This perspective not only demonstrates promising applications of PIE in the fields of scintillators and WLEDs, but also provides potential applications in display imaging and anti‐counterfeiting of PIE materials. Furthermore, solving the scientific disputes that exist under ambient conditions is also simply discussed as an outlook by introducing high‐pressure dimension to produce PIE.

Discovery of new phosphors with desired properties is of great significance for developing high optical quality solid-state lighting. The single-particle-diagnosis approach is an effective way to search novel phosphors by analyzing tiny single crystals screened from the fired powder mixtures. In this work, a broadband orange-emitting phosphor of Sr3Si8O4N10:Eu2+ for solid state lighting was discovered by this method. The new oxonitridosilicate crystallizes in the monoclinic space group of P21/n (No. 14) with cell parameters of a = 4.8185 Å, b = 24.2303 Å, c = 10.5611 Å, β = 90.616°, and Z = 4. The crystal structure of Sr3Si8O4N10 was determined from the single-crystal X-ray diffraction (XRD) data of a single crystal, which is made up of a three-dimensional framework consisting of vertex-sharing SiN4 and SiN3O tetrahedra. Sr2+ ions occupy five crystallographic sites and have coordination numbers between 6 and 8 with one ordered Sr and other four disordered Sr atoms. The multiple Sr sites lead to a broadband emission centered at 565–600 nm and a bandwidth of 128–138 nm. The internal and external quantum efficiencies (IQE/EQE) of the title phosphor are 48.6% and 29.1% under 450 nm excitation, respectively. To improve the accuracy and speed of distinguishing phosphor particles in fired powder mixtures, a microscopic imaging spectroscopy is developed and demonstrated to modify the single-particle-diagnosis method.

In this work, novel highly efficient cyan-emitting Ce3+-activated CaLu 2 HfGaAl 3 O 12 (abbreviated as CLHGAO) garnet-structured phosphors were synthesized using the high-temperature solid-state reaction route. Rietveld refinement results demonstrate the as-prepared samples belong to cubic space group Ia 3 ‾ d. These CLHGAO: x Ce3+ (x = 0.5–8%) phosphors possessed a broad absorption band in the 320–450 nm wavelength range with a maximum at 408 nm. Upon 408 nm excitation, the CLHGAO:0.5%Ce3+ sample showed a broad cyan emission band within 425–750 nm wavelength range (emission peak: 493 nm; bandwidth: 95 nm), along with CIE color coordinates of (0.1939, 0.3533) and a high internal quantum efficiency of 81.9%. It is observed that, with increasing Ce3+ doping concentration from 0.5% to 8%, the emission peak position of CLHGAO: x Ce3+ moves from 493 nm to 527 nm, and the corresponding emission color changes from cyan to green. Besides, the thermal stability and color stability of CLHGAO:0.5%Ce3+ phosphor at high temperature are also studied. A white LED device was fabricated by utilizing a 395 nm LED chip with as-prepared CLHGAO:0.5%Ce3+ cyan-emitting phosphor and commercial (Ba,Sr) 2 SiO 4 :Eu2+ green-emitting phosphor and commercial CaAlSiN 3 :Eu2+ red-emitting phosphor, and it demonstrates a high-color-quality white light with high color rendering index of 91, low color correlated temperature of 3547 K and good luminous efficacy of 58.71 lmW−1. [ABSTRACT FROM AUTHOR]

Efficient broadband green-emitting phosphors are promising for application in high color rendering white light-emitting diodes (LEDs). In this paper, we report on the preparation, crystal structure and photoluminescence properties of a novel green-emitting Ca 2 LaHf 2 GaAl 2 O 12 :Ce3+ (CLaHGA) garnet-type phosphor. All these CLaHGA: x Ce3+ (x = 4, 6, 8, 10, and 12 mol%) phosphors have been synthesized through using the conventional high-temperature solid-state reaction method. It has been found that the optical property of phosphors critically depends on Ce3+ content, and the optimal doping concentration of Ce3+ ions is 6 mol%. The optimal CLaHGA:6%Ce3+ sample has a cubic structure with the space group Ia 3 ‾ d and lattice parameters of a = b = c = 12.62662 Å and V = 2013.08 Å3. The CLaHGA: x Ce3+ phosphors exhibit an intense absorption band in the 300–485 nm range with a peak at 421 nm, due to the spin-allowed and parity-allowed 4f→5d transition of Ce3+ ions. Upon 421 nm excitation, CLaHGA: x Ce3+ phosphors give rise to bright broad green emission bands in the 435–750 wavelength region with peak ranging from 519 to 531 nm, owing to the spin-allowed and parity-allowed 5d→4f transition of Ce3+ ions. For the optimal CLaHGA:6%Ce3+ sample, its CIE color coordinates and internal quantum efficiency are determined to be (0.3135, 0.4851) and 40.7%, respectively. The full width at half maximum of CLaHGA:6%Ce3+ is much larger than the commercial (Ba,Sr) 2 SiO 4 :Eu2+ green phosphor (124 nm versus 71 nm), while its emission intensity is only about 39% of that of (Ba,Sr) 2 SiO 4 :Eu2+. Besides, the thermal stability of CLaHGA:6%Ce3+ has also been studied. A white LED device is fabricated using the synthesized CLaHGA:6%Ce3+ green phosphors, showing a bright warm-white light emission with high color rendering index of Ra = 89.7 and low correlated color temperature of 4058 K. [ABSTRACT FROM AUTHOR]

The Li6AlGd(1−x)(BO3)4:xTb3+ (0 ≤ x ≤ 4.0 mol%) phosphors are fabricated via solid‐state reaction process. The structural investigations are carried out through powder X‐ray diffraction and Fourier transform infrared techniques. The morphology is examined using high‐resolution scanning electron microscope and transmission electron microscope. The temperature‐dependent luminescence properties are completed at 378 nm excitation. The photoluminescence excitation analysis is carried out by controlling the emission at 545 nm corresponding to Tb3+:5D4 → 7F5 transition. The suitable excitation wavelength is selected as 378 nm for efficient emission by studying the emission spectra at several excitation wavelengths. The emission spectra show two groups of emission bands through Tb3+:5D3 → 7FJ and Tb3+:5D4 → 7FJ transitions. The concentration‐dependent investigations reveal the optimum Tb3+ions concentration as 2.0 mol% for intense luminescence. Upon 378 nm excitation, they produce greenish‐yellow luminescence of color purity 60% with CIE color coordinates (0.286, 0.572) close to the standard European Broadcasting Union Green Illuminant and they found suitability in the design of solid‐state lighting devices. [ABSTRACT FROM AUTHOR]

The red-emitting phosphor YAl3(BO3)4: Eu3+ (Yttrium Aluminum Borate) is synthesized by a simple, time-saving, economical novel method of solution combustion synthesis at 500 °C, a comparatively lower temperature using urea and glycine as fuel. In this work, the phosphor YAl3(BO3)4: Eu3+ is synthesized for the first time in one step at 500 °C by the combustion method. Europium as a doping in Yttrium Alunium borate phosphor gives intense emission in the red region having a prominent emission band at 614 nm with the excitation at 395 nm. This excitation band at 395 nm makes phosphor, a good red emitter for the n-UV LED for making w-LED for solid-state lighting. The phosphor YAl3(BO3)4: Eu3+ was also investigated for long-lasting or persistent luminescence for the first time. We observed long-lasting emission in the YAl3(BO3)4: Eu3+phosphor treated in reducing atmospheres, upon UV irradiation (254 nm) using emission from a Xe lamp (Hitachi F-7000).

High-brightness laser lighting requires high luminous efficacy and high thermal performance of luminescent materials. In this study, we designed and fabricated single-phase YAG:Ce ceramics with differential grain sizes by combining the coarse commercial phosphor and fine powder of precusor. The large YAG:Ce grains mainly contribute to excellent luminescence properties. The small YAG:Ce grains not only change the direction of light propagation to improve the luminous efficiency but also effectively increase the Ce3+ content to improve the absorption of blue light, which significantly further enhance the luminescence properties compared with the second phase in the YAG:Ce-base composite ceramics. The luminescent ceramic with 40 wt% large grains sintered under 1550 °C has the highest luminous efficacy of 398.5 lm/W. Compared with the Al 2 O 3 –YAG:Ce composite ceramic, the single-phase YAG:Ce ceramic effectively increased the absorption of blue light to enhance the luminescence properties without the adverse effects caused by the transverse scattering of light in the Al 2 O 3 phase. After encapsulating the ceramic onto a radiator, a high luminous flux of 7697.6 lm under the blue-laser excitation of 3.0 A (54.6 W) was obtained. These indicated its broad application prospects in high-power solid-state laser lighting. [ABSTRACT FROM AUTHOR]

A series of Ca9Gd(VO4)7: Dy3+ (x = 0.01–0.20) nanophosphor crystals emitting a cool white light were synthesized by solution combustion methodology. The X-ray diffraction patterns were analyzed and processed using Rietveld refinement. The fabricated nanophosphor was found to crystallize in a trigonal crystal lattice with space group R3c(161). The morphological behavior of the prepared nanophosphor was investigated using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The photoluminescence properties of the nanophosphor correspond to cool white emission upon near-ultraviolet (NUV) excitation at 327 nm due to 4F9/2 → 6H15/2 (bluish) and 4F9/2 → 6H13/2 (yellowish) radiative relaxations at 487 nm and 576 nm respectively. Also, there is a strong occurrence of double charge transfer from O2− ions to Dy3+ and V5+ ions with the latter being stronger due to the high positive charge of V5+ ions. Color coordinates (x = 0.2878, y = 0.3259) are consistent with white emission. Auzel's model was implemented to examine the non-radiative relaxation (113.5 ms−1), radiative lifetime (1.4856 ms), and quantum efficiency (83.13%) values. The crystalline and optical behavior of the synthesized cool white emitting nanophosphor facilitates its use in near-UV-based WLEDs and other advanced solid-state lighting. [ABSTRACT FROM AUTHOR]

The BiPO4:Ln (Ln = Dy3+, Tb3+ and Sm3+) phosphor were prepared using wet chemical synthesis and studied its photoluminescence properties. Under 352 nm excitation, the BiPO4:Dy3+ phosphor shows the blue (481 nm) and yellow (575 nm) emissions due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of the Dy3+ ion, respectively. When BiPO4:Tb3+ phosphor was excited at 378 nm, it emits efficient narrow green emission at 545 nm due to 5D4 → 7F5 transition. The BiPO4:Sm3+ phosphor shows yellow, orange and red emissions centred at 598 nm, which is attributed to the 4G5/2 → 6H7/2 transition of the Sm3+ ion. The CIE coordinates indicate that the prepared phosphors have high colour purity. The photoluminescence results suggests that BiPO4:Ln (Ln = Dy3+, Tb3+ and Sm3+) phosphor may be used as a possible material for near-UV-based solid-state lighting. [ABSTRACT FROM AUTHOR]

Solid-state lighting (SSL) devices are ubiquitous in several markets, including architectural, automotive, healthcare, heritage conservation, and entertainment lighting. Fine control of the LED light output is crucial for applications where spectral precision is required, but dimming LEDs can cause a nonlinear response in its output, shifting the chromaticity. The nonlinear response of a multi-color LEDs can be corrected by curve-fitting the measured data to input dimming controls. In this study, the spectral output of an RGB LED projector was corrected using polynomial curve fitting. The accuracy of four different measurement methods was compared in order to find the optimal correction approach in terms of the time and effort needed to perform measurements. The results suggest that the curve fitting of very high-resolution dimming steps (n = 125) significantly decreased the chromaticity shifts between measured (actual) and corrected spectra. The effect size between approaches indicates that the curve-fitting of the high-resolution approach (n = 23) performs equally well as at very high resolution (n = 125). The curve-fitting correction can be used as an alternative approach or in addition to existing methods, such as the closed-loop correction. The curve fitting method can be applied to any tunable multi-color LED lighting system to correct the nonlinear dimming response.

The dye-sensitized solar cell (DSSC) has been on the market as a permanent power source for indoor IoT edge devices. In recent years, indoor illumination technology has been experiencing a drastic transition from incandescent and fluorescent lamps toward solid-state lighting devices with light-emitting diodes (LEDs). In addition to the high power efficiency, a virtue of LEDs is their prompt response, which enables precise change of the illumination level using pulse-width modulation (PWM) of the current source, and thus PWM illumination is commonly installed in society. The light intensity change from off to on states of an LED under PWM driving is literally infinity, which causes the lighting to flicker. The lighting flicker induces not only an optical illusion but also biological effects, including serious health problems, which can be mitigated by raising the modulation frequency. Because the peak intensity of a PWM illumination can be 100 times that of the average intensity, the indoor solar cell, which has a relatively high series resistance, is expected to underperform. In this paper, the characteristics of a commercial indoor DSSC under PWM illumination are studied. It is found that while PWM illumination at low frequency seriously deteriorates the performance of the DSSC, it recovers at high frequency. The latter feature is not found in indoor amorphous-Si solar cells, and the electrochemical impedance spectroscopy revealed that it stems from the electrochemical nature of some components of the series impedance in the DSSC, offering a key piece of evidence of the superiority for use in the modern indoor application of the DSSC over traditional amorphous-Si solar cells. [ABSTRACT FROM AUTHOR]

0D hybrid organic–inorganic metal halides have attracted significant interest due to their unique optoelectronic properties, but attainment of efficient and stable white light emission (WLE) in such compounds remains a challenge. Here, efficient WLE via a molecular design that couples intracompound charge transfer and cluster‐centered excited states in 0D halide hybrids is demonstrated. Two Cu(I) halide hybrids, K(18‐crown‐6)Cu2Br3 and Na4(18‐crown‐6)5In2Cu4Br14·8H2O, are synthesized wherein luminescent [Cu4Br6]2− clusters are isolated from each other and surrounded by 18‐crown‐6 coordinated alkali metal cations. In the case of K(18‐crown‐6)Cu2Br3, [Cu4Br6]2− clusters are only partially isolated, leading to strong orange emission with a photoluminescence quantum yield (PLQY) of 53% under UV excitation. Strikingly, to a larger extent of isolation as that, in Na4(18‐crown‐6)5In2Cu4Br14·8H2O as a result of the incorporation of nonemissive [InBr4]− clusters, intense white light emission with a PLQY of 97% is achieved. The dual cluster‐centered states, coupled with a mixed metal‐to‐ligand and halide‐to‐ligand charge transfer state, are responsible for this bright white luminescence. This work provides new design principles for expanding the materials library for single‐component, solid‐state WLE. [ABSTRACT FROM AUTHOR]

An efficient urea-assisted SC (solution-combustion) approach was used to synthesize a novel series of doped Ca0.5Bi3P2O10: xDy3+ nanophosphors (0.01–0.1 mol). The powdered materials were thoroughly investigated using structural and optical measures. 'Rietveld refinement' investigations found that the produced nanophosphor formed a triclinic system with the P -1 triclinic space group. An EDS (energy-dispersive spectral) study was conducted to determine the corresponding proportions of constituent elements of doped nanophosphors. The TEM (transmission electron microscopy) revealed aggregated particles with a standard size on the nanoscale. The PLE (Photoluminescence excitation) spectrum indicates that the indicated phosphors can be stimulated by NUV (near ultraviolet) illumination sources. The Dy3+-ions undergo transitions from (4F9/2 → 6H15/2 & 4F9/2 → 6H13/2) were recognized as (PL) spectra with an excitation of 353 nm revealed the presence of blue-yellow bands at 481, and 577 nm, correspondingly. Further, PL data was used to determine photometric metrics such as CCT (correlated color-temperature), CC (chromaticity-coordinates (x & y)), and CP (color-purity (%)), supporting their use in solid-state lighting and latent fingerprinting applications. [ABSTRACT FROM AUTHOR]

The performance of commercially available retrofit LED tubes intended for the replacement of linear fluorescent lamps is measured and analyzed with respect to "real-world" installed electronic ballasts, as ascertained through field recovery from installed bases, such as office buildings, parking garages, and industrial installations in western Europe from 2018 to 2020. Results show a wide variation in lamp power draw, which not only thwarts the energy-saving and climate protection aspects of the LED retrofit solution but also poses potential safety risks. Given the EU's goals under the Restriction of Hazardous Substances (RoHS) directive to phase out mercury-containing fluorescent lighting, starting from September 2023, the situation is alarming. We show that this lamp power spread is due to the fundamental differences in impedance between fluorescent lamps and LEDs, in combination with the passive nature of the driver electronics that are currently employed in commercially available LED tube lamps. In response to this disparity, a novel driver topology including active power control (APC) is introduced, which shows that the power-spread problem can be avoided, and we offer a manufacturable solution. A prototype retrofit LED tube lamp incorporating this APC driver technology is shown to deliver safe and predictable energy savings, outlining a path toward guaranteeing the expected return-on-investment and positive environmental impact of the solid-state lighting replacement of mercury-containing linear fluorescent lamps. [ABSTRACT FROM AUTHOR]

While junction temperature control is an indispensable part of having reliable solid-state lighting, there is no direct method to measure its quantity. Among various methods, temperature-sensitive optical parameter-based junction temperature measurement techniques have been used in practice. Researchers calibrate different spectral power distribution behaviors to a specific temperature and then use that to predict the junction temperature. White light in white LEDs is composed of blue chip emission and down-converted emission from photoluminescent particles, each with its own behavior at different temperatures. These two emissions can be combined in an unlimited number of ways to produce diverse white colors at different brightness levels. The shape of the spectral power distribution can, in essence, be compressed into a correlated color temperature (CCT). The intensity level of the spectral power distribution can be inferred from the luminous flux as it is the special weighted integration of the spectral power distribution. This paper demonstrates that knowing the color characteristics and power level provide enough information for possible regressor trainings to predict any white LED junction temperature. A database from manufacturer datasheets is utilized to develop four machine learning-based models, viz., k-Nearest Neighbor (KNN), Radius Near Neighbors (RNN), Random Forest (RF), and Extreme Gradient Booster (XGB). The models were used to predict the junction temperatures from a set of dynamic opto-thermal measurements. This study shows that machine learning algorithms can be employed as reliable novel prediction tools for junction temperature estimation, particularly where measuring equipment limitations exist, as in wafer-level probing or phosphor-coated chips. [ABSTRACT FROM AUTHOR]

The need of new materials with desirable optical properties has become important in recent years. In particular, a need has emerged for compounds having better luminescence properties in various practical applications. The introduction of rare earth ions as activators improves the luminescence properties of the compounds considerably. Boron is one of the most abundant elements in nature. It readily combines with almost all other elements. In combination with oxygen; it forms borates comprised of various anions such as BO33−, B2O54−, etc. Apart from these simple borates, several complex compositions exist involving mixed anions as well as double metal borates, due to the three‐fold, or four‐fold coordination of borate atoms. Borates intrinsically possesses characteristics that are advantageous for optical materials, which include a wide transparency range, large electronic band gap, good thermal and chemical stability, low preparative temperature, optical stability with good nonlinear characteristics, and an exceptionally high optical damage threshold. The unique crystal structure of borates determines their enhanced ultraviolet light transparency, good nonlinearity, and relatively high resistance against laser‐induced damage. Some of these complex borates have interesting luminescence properties that are covered in this review. These include double borates containing rare earths RM3(BO3)4, pentaborates LaMgB5O10, M3R2(BO3)4, where M is an alkaline earth, mixed anion borates such as aluminoborate SrAl2B2O7, silicate‐borates such as pekovite, SrB2Si2O8, haloborates, M2B5O9X, where M is an alkaline earth and X is a halogen, phosphate borates, and MBPO5, where M is an alkaline earth. Phosphors based on these compositions find use in various applications such as fluorescence lamps, colour TVs, plasma display panels, high‐intensity discharge lamps based on xenon, optically pumped solid‐state lasers, eye‐safe lasers, and X‐ray imaging. [ABSTRACT FROM AUTHOR]

Narrow band red-emitting phosphors based on organo-Eu(III) complexes prove their energetic features with surprising performance in smart red/white LEDs, sensing, and biological fields. In this report, a series of unique Eu(III) complexes have been synthesized with coumarin integrated with a class of phenanthroline(Phen)/thiabendazole(TBZ) based ancillary ligands and dibenzoyl methane (DBM)/2-theonyl trifluoroacetone (TTA) as an anionic ligand. The computational study reveals that the TBZ/Phen-based neutral ligands are superior energy harvesters to those other reported analogue neutral ligands. All the Eu-complexes demonstrated outstanding red emission due to electric dipole (ED) transition ( 5 D 0 → 7 F 2 ) in solid, solution, and thin film with high quantum yield (QY). Theoretical analysis (TD-DFT) and experimental findings describe that the energy transfer (ET) from the ligand's triplet level to the Eu(III) ion is completely occurring. The Eu(III) complexes can potentially be used to fabricate intense hybrid white and red LEDs. All of the fabricated red LEDs revealed high luminous efficiency of radiation (LER) values. The fabricated blue LED based hybrid white LEDs displayed remarkable performance with a low correlated color temperature (5634 K), high color rendering index 88%, and CIE values ( x = 0.33; y = 0.342) for 3Eu. By interaction with acid-base vapors, Eu-complexes displayed effectively alterable on-off-on luminescence. Further, cellular imaging shows that Eu-complexes can be a potential biomarker for cancer cell lines.

In this work, a series of Ce3+ activated Sr3Y(BO3)3 phosphors were synthesized by the solution combustion method. The synthesized phosphors were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy for their structural and morphological studies. Further, the optical properties of phosphors were studied via photoluminescence emission (PLE) spectroscopy. The results showed a broad photoluminescence excitation wavelength band from 250 to 380 nm. The PLE spectrum consists of a major peak centered at 340 nm. Concentration quenching for 433 nm emission line is observed at 8 mol% of Ce3+ ion and it is due to electrical multipolar interaction. The non-radiative transition between Ce3+ ions occurs via dipole–dipole interaction for the concentration quenching of Ce3+ in Ce3+ doped Sr3Y(BO3)3. The CIE-coordinates for PL emission at 8 mol% concentration of Ce3+ are obtained as (X = 0.1677, Y = 0.0078). [ABSTRACT FROM AUTHOR]

Broadband emission with a large Stokes shift is of interest for applications in solid‐state lighting. Such emission is often achieved with self‐trapped excitons; however, in reduced‐dimensional perovskites, high‐performance self‐trapped emission has, until now, been widely observed only in lead‐based materials. Here, the synthesis in an air ambient of reduced‐dimensional Sn‐based perovskite phosphors R2 +xSnI4 +x [R = octylammonium (OTA), hexylammonium (HA) or butylammonium (BA)] is reported, an advance achieved by tailoring the synthesis of the Ruddlesden‐Popper 2D perovskites R2SnI4. The lead‐free R2 +xSnI4 +x phosphors have broadband self‐trapped emission with over 80% photoluminescence quantum yield (PLQY) and more than a 150 nm Stokes shift. White‐light‐emitting diodes (WLEDs) based on OTA2 +xSnI4 +x phosphors exhibit warm‐white emission (correlated color temperature = 2654K) suited to home lighting, and a CRI of 92, among the best for Pb‐free perovskite WLEDs reported to date. [ABSTRACT FROM AUTHOR]

An active region design based on InGaN / delta-InN quantum well (QW) with AlGaN interlayer (IL) and GaN barriers (delta-structure) is investigated for potential high-efficiency visible light emitters. Numerical simulations demonstrate a large wavelength redshift with a simultaneous increase of the electron-hole wavefunction overlap for the delta-structure as compared to the conventional InGaN QW with AlGaN IL and GaN barriers. Proof of concept experimental growths via the metalorganic chemical vapor deposition demonstrate the effect of the delta-InN insertion into the conventional InGaN-based QW. [ABSTRACT FROM AUTHOR]

GaN-based μLEDs with superior properties have enabled outstanding achievements in emerging micro-display, high-quality illumination, and communication applications, especially white-light visible light communication (WL-VLC). WL-VLC systems can simultaneously provide white-light solid-state lighting (SSL) while realizing high-speed wireless optical communication. However, the bandwidth of conventional white-light LEDs is limited by the long-lifetime yellow yttrium aluminum garnet (YAG) phosphor, which restricts the available communication performance. In this paper, white-light GaN-μLEDs combining blue InGaN-μLEDs with green/red perovskite quantum dots (PQDs) are proposed and experimentally demonstrated. Green PQDs (G-PQDs) and red PQDs (R-PQDs) with narrow emission spectrum and short fluorescence lifetime as color converters instead of the conventional slow-response YAG phosphor are mixed with high-bandwidth blue InGaN-μLEDs to generate white light. The communication and illumination performances of the WL-VLC system based on the white-light GaN-based μLEDs are systematically investigated. The VLC properties of monochromatic light (green/red) from G-PQDs or R-PQDs are studied in order to optimize the performance of the white light. The modulation bandwidths of blue InGaN-μLEDs, G-PQDs, and R-PQDs are up to 162 MHz, 64 MHz, and 90 MHz respectively. Furthermore, the white-light bandwidth of 57.5 MHz and the Commission Internationale de L'Eclairage (CIE) of (0.3327, 0.3114) for the WL-VLC system are achieved successfully. These results demonstrate the great potential and the direction of the white-light GaN-μLEDs with PQDs as color converters to be applied for VLC and SSL simultaneously. Meanwhile, these results contribute to the implementation of full-color micro-displays based on μLEDs with high-quality PQDs as color-conversion materials. [ABSTRACT FROM AUTHOR]

Mn4+-doped fluoride phosphors are attractive for application in white solid-state lighting devices because their distinct red emission can improve the color rendering index, while the earth-abundance of Mn4+ ions can reduce the production cost. However, highly hazardous HF is used as the fluoride source in the synthesis processes, which requires extreme caution. In this review, we introduce various methods for synthesizing Mn4+-doped fluoride phosphors, categorized according to the presence or absence of HF in the synthesis. The underlying optical properties of the phosphors fabricated using the various methods are discussed. In addition, in the discussion of each method, we emphasize on the key factors and strategies for developing phosphors. Finally, this review highlights perspectives on and future directions for the safe synthesis of Mn4+-doped fluoride phosphors to achieve solid-state lighting devices with superior optical properties.

Er3+ activated Sr 3 WO 6 double perovskite crystallized in triclinic structure was synthesized via the solid-state reaction method at 1200 °C for non-contact optical thermometry and solid-state lighting. The phosphors under study were characterized via X-ray diffraction, scanning electron microscopy, diffusion reflectance spectra, and photoluminescence techniques. When excited with 380 nm, the Sr 3 WO 6 :Er3+ phosphors exhibited intense green emission, corresponds to 2H 11/2 /4S 3/2 -4I 15/2 transitions of Er3+. The fluorescence intensity ratio of thermally coupled energy levels were computed within 303–513 K and subsequent relative sensitivity (0.56% K−1 at 303 K) was determined. Moreover, the PL intensity maintained 76.28% at LED burning temperature (150 °C) compared to PL intensity observed at room-temperature, denotes good thermal stability. Additionally, the fluorescent behaviour of the phosphors was examined via PL decay lifetime study. The PL quantum efficiency of the phosphor is computed via the Auzel's model using PL decay lifetime, and was obtained to be 80.32% for Sr 3 WO 6 :2% Er3+ phosphor. [ABSTRACT FROM AUTHOR]

The synthesis of novel nanophosphors exhibiting unique morphologies with high purity, stability, eco-friendliness, and a high color rendering index is crucial to meet the demands of contemporary solid-state lighting energy devices. In this investigation, we successfully synthesized Na 0.2 Sr 0.9-x ZrO 3 : x Er3+ perovskite nanophosphors. All samples manifested an orthorhombic structure. The crystallite size was observed to increase with rising concentrations of Er3+. The optical band gap exhibited a range of 5.19 eV to 5.36 eV with increments in doping concentration, signifying alterations in the lattice constants attributable to crystalline disorder. The downshifting PL spectra revealed both host emission bands and dopant (Er3+) emission lines. The violet – blue band was attributed to crystalline disorder while the red emission band was assigned to octahedra tilting disorder in the perovskite. The presence of Er3+ ion lines at 523 and 546 nm produced intense green light, as depicted in the CIE chromaticity diagram for all doped samples. The study affirms that the phosphors synthesized in this research possess potential for application in the development of visible green lamps for optical display devices and solid-state lighting. • Downconversion or upconversion phosphor. • Energy level diagram for the DS mechanism. • To study electronic absorption processes in prepared nanoparticles. • The quantum confinement resulting from the small crystal sizeCross relaxation may also occur in the red emission band. • Is attributed to lattice vibrations related to the Sr2+ ion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel down-conversion Ba 2 BiV 3 O 11 :Eu3+ nanophosphors were synthesized via a solution combustion approach. • Crystal structure along with phase purity is described by the Rietveld Refinement technique. • The detailed structural and photoluminescence analysis is done effectively. • Inokuti-Hirayama (I-H) model was executed to examine the concentration quenching mechanism. • Significant utilization in various solid-state lighting devices, wLEDs, and solar cells. Nanocrystalline Ba 2 BiV 3 O 11 phosphor activated with lanthanide ion (Eu3+) has been successfully developed via a solution combustion approach. Various characterization techniques were implemented to explore the crystal structure, morphological behavior, photoluminescence, and chromatic aspects of Eu3+: Ba 2 BiV 3 O 11 nanophosphors. Rietveld refinement was exercised to attain the phase purity and various crystallographic parameters. Transmission Electron Microscopy (TEM) technique was employed to analyze the crystallite size of the developed nanocrystals which is also in agreement with the size calculated from Scherrer formalization and W-H (Williamson-Hall) plot. Morphological behavior was studied with the help of Scanning Electron Microscopy (SEM) measurements. The most intense peak centered at 622 nm (5D 0 → 7F 2) in emission spectra was noted for Eu3+: Ba 2 BiV 3 O 11 nanophosphors under 348 nm excitation. Kubelka-Munk function computed the E gap for the host along with the optimized sample and the outcomes evolved as 3.47 eV and 3.41 eV, respectively. Auzel's model was executed to attain the radiative lifetime (1.3467 ms) for 5D 0 electronic state. The CIE coordinates (x = 0.5990, y = 0.4003), CCT values (1710 K), quantum efficiency (87 %), and emission of bright red light indicate the promising behavior of Ba 2 Bi 0.9 Eu 0.1 V 3 O 11 nanophosphor to use in the imaging applications, wLEDs, temperature sensing, and solid-state lighting (SSLs) appliances. [ABSTRACT FROM AUTHOR]

Wedemonstrate a high-speed light fidelity (LiFi) communication system deploying ultra-high brightness laser-based white light illumination sources in a surface mount device (SMD) packaging platform. The LiFi transmitter SMD source provides 450 lumens of white light output with a brightness of 1000 cd/mm2 in a dual wavelength configuration comprising blue and infrared (IR) emitting laser diodes within the SMD. First, we present high-speed data transmission beyond 25 Gbit/s over a 3 meter channel distance with the combined data rates from the blue and IR lasers in the single SMD. Next, we present a 2.8 Gbit/s data rate with the dual wavelength laser SMD light source using a side-emissive fiber as the transmitter. This work proves the viability of LiFi systems deploying laser-based white light sources operating at very high data rates with the visible light and communication signal delivered in conventional free-space transmission architectures along with novel configurations using side-emitting fibers. [ABSTRACT FROM AUTHOR]

The presented study deals with white light emission from Dy3+-activated Ba2ZnSi2O7 phosphors with a variable concentration of the dopant (0.1–2.5 mol.%). Ba2ZnSi2O7:Dy3+ phosphors are prepared using the modified solid-state synthesis method. The structural analysis of phosphors was conducted using the powder X-ray diffraction analysis (XRD), and refined parameters were calculated using the match software. Morphology and particle size were analysed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Intense white light emission with the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (0.30, 0.33) was achieved for an optimal doping concentration of 1.5 mol.%. Highest emission intensity was obtained for the 487, 544 and 594-nm emission, indicating its potential applicability in the fields of lighting and displays. Thermoluminescence (TL) glow curves are composite in nature and a broad band, found at 300°C, was deconvoluted by the computerized glow curve deconvolution program to calculate its kinetic parameters. The glow curve intensity increases upon increasing the UV exposure time. This study is useful in detecting trap parameters and TL dosimeters. [ABSTRACT FROM AUTHOR]

An attempt has been made to synthesize orange–red light‐emitting rare earth‐doped polymer matrices Eu0.5Sm0.5(TTA)3tppo (Eu = europium, Sm = samarium, TTA = thenoyltrifluoroacetone, tppo = triphenylphosphine oxide) hybrid organic complex by solution technique. Blended thin films were made by molecularly doping the complex in polymethylmethacrylate (PMMA) and polystyrene (PS) polymers at different weight percentages (5%, 10%). These films were solvated in basic and acidic media to explore the effect of solvent on its luminescence properties. UV–visible absorption spectra of these solvated films portray two peaks corresponding to π→π* and n→π* optical transitions in the range 240–275 nm and 370–390 nm in basic medium. Energy band gap of these thin films in basic medium was found between 3.16 eV to 3.20 eV and 3.12 eV to 3.22 eV in acidic medium. Photoluminescence spectra of all films in dichloromethane showed an intense peak at 614 nm, whereas in formic acid, the same were found at 475 nm, which fell in the orange–red and blue region of the visible spectrum, respectively. CIE coordinates of these solvated films in various solvents and at different weight percentages revealed tunable orange–red to blue light emission with change in polarity of the solvent. Therefore the synthesized complexes blended in the polymers can be shaped into flexible films for fabrication of organic light‐emitting diodes (OLEDs) with consistent results, proving their prospect as colour tunable light emissive materials for OLED devices, lasers, displays, and solid‐state lighting. [ABSTRACT FROM AUTHOR]

Precession electron diffraction (PED) was used to measure the long‐range order parameter in lattice‐mismatched AlInP epitaxial films under investigation for solid‐state‐lighting applications. Both double‐ and single‐variant films grown at 620, 650 and 680 °C were analysed in TEM cross‐section. PED patterns were acquired in selected‐area‐diffraction mode through external microscope control using serial acquisition, which allows inline image processing. The integrated peak intensities from experimental patterns were fit using dynamical simulations of diffraction from the ordered domain structures. Included in the structure‐factor calculations were mean atomic displacements of the anions (P) due to ordering, which were found by valence‐force‐field calculations to have a nearly linear dependence on order parameter. A maximum order parameter of S = 0.36 was measured for a double‐variant specimen grown at 650 °C. [ABSTRACT FROM AUTHOR]