Solid-state Lighting Applications Research Articles

Spectroscopic properties, Judd Ofelt analysis of U and Eu activated Li2O-ZnO-SrO-B2O3-P2O5 borophosphate glasses for solid-state lighting applications

Uranium and europium doped borophosphate glasses with the base composition of (Li2O)(ZnO)0.5(SrO)0.4(B2O3)2.55(P2O5)0.5 were synthesized by melt -quenching. The X-ray diffraction profile affirmed that all the synthesized samples were devoid of crystallinity and amorphous in structure. The absence of precipitations/grains in the scanning electron micrographs further validated the amorphous character and compositional homogeneity of the prepared glass. The FTIR spectra revealed several prominent vibrational bands in 713–1568 cm−1 range and were assigned to the corresponding B-O-B and P-O-P and B-O-P bonding. The thermal characteristics of the synthesised glass samples were investigated using differential thermal analysis experiments. The broad photoluminescence (PL) spectra observed for the uranium doped glass with emission maxima at 523 nm resembles the hexavalent U(VI) emission in a disordered amorphous environment. The emission profile of the Eu doped glass displayed several characteristics peaks due to 5D0 → 7FJ transitions. The phonon energy of the base glass was found to be 1005 cm−1. The Judd-Ofelt analysis showed that for all the doped glass, the JO intensity parameter Ω4 was always greater than Ω2 indicating that Eu3+ ions are primarily arranged in a centrosymmetric environment in the studied host. Radiative properties of 5D0 → 7FJ=1-4 transitions of the Eu3+ such as branching ratios, emission cross-section, and transition probabilities were computed. Energy transfer pathways of UO22+ → Eu3+ in the codoped borophosphate glass were described. The CIE chromaticity and PL results suggest that the intense red emission of Eu doped glasses could be useful for phosphor applications.

Systematic First-Principles Calculations of Ce3+-Dopant in Garnet-Type Oxide Phosphors

A study of Ce3+-doped oxide phosphors was performed using first-principles calculations based on the relativistic DV-Xα method. In particular, we focused on the Ce3+-doped garnet-type oxides, which have potential applications in solid-state lighting and display devices. The electronic structure and optical properties of the phosphors were analyzed. The energy levels of the Ce3+ ions were affected by the coordination number and the crystal field strength of the surrounding oxygen ions. In addition, the crystal structure of the material had a significant impact on the energy levels of the Ce3+ ions, with different crystal structures leading to different energy levels.The Ce3+ ion is substitutionally incorporated in the garnet lattice, and the 4f electron of Ce3+ plays an important role in the luminescence of the material. The emission wavelengths of the 5d-4f transition energy of Ce3+ can be tailored by varying the crystal structure and the composition. The 5d orbitals of Ce3+ are substantially affected by the crystal field splitting while the amplitude of crystal field splitting (εcfs) is caused by many parameters: coordination number, symmetry of Ce3+ site, and bond lengths between the Ce3+ ion and the oxygen ions (O2-). This study incorporated the following computational conditions: i) lattice relaxation, ii) the choice of the exchange-correlation potential, and iii) Slater’s transition state method. The effects of these conditions were analyzed. In addition, the correlations among physical properties and electronic structure parameters were also investigated in detail.The first-principles calculation results were compared to the experimental data to validate the accuracy of the theoretical models, which showed a good agreement between the experimental and predicted values.

Synthesis and characterization of thermally stable red light-emitting Eu3+ activated Li7La3Zr2O12 phosphors for solid-state lighting applications

To enhance the photoluminescence property of Li7La3Zr2O12 (LLZO), Eu was doped using a solid-state synthesis technique. X-ray diffraction and Raman spectroscopy analysis were used to examine the crystal structure of the synthesized phosphors. The optical band gap values of pristine and Eu3+ doped LLZO phosphor investigated using ultraviolet-visible (UV-Vis) spectroscopy were measured to be 2.74 and 2.97 eV, respectively. The wavelengths of pure and doped LLZO samples were measured and fitted by the Commission Internationale de l’Eclairage (CIE) chromatic coordinate graph. These samples were found to emit blue emission at 354 nm (pure LLZO) and red emission at 464 nm (doped phosphor), which correspond to the 5D0 to 7Fj (j = 0, 1, 2, and 3) transition. The purity of the color and correlated color temperature with respect to the 0.9 M.W% Eu3+ doped (activated) LLZO sample were estimated to be 80% and 1719K, respectively. The indication of its maximum emissive capability at this rate was found suitable for aesthetic lighting applications.

Spectroscopic properties and thermal stability of a Mn4+-doped polyfluoride phosphor for application in solid-state lighting

In this study, an efficient polyfluoride red-emitting phosphor, Cs3RbGe2F12:Mn4+ (denoted as CRGF:Mn), has been synthesized using a simple co-precipitation method. The crystal and electronic structures, spectroscopic properties, and photoluminescence thermal stability of CRGF:Mn have been systematically characterized. The results show that Mn4+ ions experience a strong crystal field and present a series of intense red emission peaks under blue light excitation. Moreover, CRGF:Mn exhibits a high color purity (95.1 %), high internal quantum efficiency (82.4 %), and enhanced photoluminescence thermal stability at 150 °C, with an intensity of 113 % relative to room temperature. A warm white light-emitting diode exhibiting a low correlated color temperature (3572 K), high color rendering index (90.7), and suitable luminous efficiency (132.6 lm/W) was prepared using CRGF:Mn as a red component, demonstrating viable application in solid-state lighting.

Investigating Fe-doped yttrium oxide nanophosphors for enhanced latent fingerprint visualization and deep learning analysis

In the study, synthesized Fe3+ doped yttrium oxide nanophosphors (Y2O3:Fe NPs, 1–11 mol%), including structural, microstructural, chemical state, optical, thermal, and photoluminescence properties, are extensively studied. An optimized 7 mol % Fe doped Y2O3 NPs powder is used to develop latent fingerprints on various surfaces through a simple powder dusting method. The developed fingerprints are visible under 254 nm UV light. The research also analyzes several pore properties: size, shape, number, position, type, and inter-distance. A fingerprint recognition deep learning model based on the YoLOv8 algorithm was developed and employed for analyzing both single and overlapped fingerprints. These highly effective NPs are also used to create a transparent anti-counterfeiting (AC) ink that exhibits AC properties when exposed to UV light, and their physical and chemical stability opens novel applications in the AC field. The optimized Y2O3:7Fe3+ NPs are an excellent luminous platform for solid-state lighting, AC, and dermatoglyphics applications.

Tilt-induced charge localisation in phosphide antiperovskite photovoltaics

Antiperovskites are a rich family of compounds with applications in battery cathodes, superconductors, solid-state lighting, and catalysis. Recently, a novel series of antimonide phosphide antiperovskites (A 3SbP, where A = Ca, Sr Ba) were proposed as candidate photovoltaic absorbers due to their ideal band gaps, small effective masses and strong optical absorption. In this work, we explore this series of compounds in more detail using relativistic hybrid density functional theory. We reveal that the proposed cubic structures are dynamically unstable and instead identify a tilted orthorhombic Pnma phase as the ground state. Tilting is shown to induce charge localisation that widens the band gap and increases the effective masses. Despite this, we demonstrate that the predicted maximum photovoltaic efficiencies remain high (24%–31% for 200 nm thin films) by bringing the band gaps into the ideal range for a solar absorber. Finally, we assess the band alignment of the series and suggest hole and electron contact materials for efficient photovoltaic devices.

Facile synthesis and photophysical properties of combustion derived Dy3+doped Ca9La(PO4)7 nanophosphors for advanced solid-state lighting applications

Globally, the energy consumption has accelerated, which has driven the research to increase sustainable energy sources. In this context, this is the first report on the exploration of the structural and photometric aspects of Dy3+ doped Ca9La(PO4)7 i.e., CLP: Dy3+ nanophosphors for designing WLEDs economically. Herein, the solution combustion method was utilized for fabricating the desired nanophosphor, thereafter their morphological behavior, and crystallite size were studied in detail via X-ray diffraction, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) techniques which confirmed the rhombohedral crystal architecture with R3c space group affirming the potential of the fabricated nanomaterials in optoelectronics. CLP: Dy3+nanophosphors depicted reproducible emission spectra with peaks at 4F9/2 → 6H13/2, 15/2 attributed to intra-configurational transitions of Dy3+ ions. The increasing dopant concentration beyond 20 mol % reduced the intensity of emission peaks which could be ascribed to the dipole–dipole interactions of the neighboring ions. The optical band gap of 5.38 eV derived via Kubelka-Munk relations established their role in semiconductors. Moreover, their Commission international de I’eclairge (CIE) chromaticity coordinates were studied in detail to reveal the emission color with color purity and Correlated Color Temperature (CCT) values. All the results favored and exemplified the incredible role of CLP: Dy3+ nanophosphors for emerging future prospects in advanced optoelectronic technology.

Luminescence properties of Eu3+ doped Li2SrSiO4 phosphor

The modified solid-state reaction method has been used in this work to prepare Eu3+ doped Li2SrSiO4. PL spectroscopy was used to investigate photoluminescence (PL) properties of the sample. X-ray powder diffraction study was used to confirm the crystalline nature and phase purity of the sample. The particle size of prepared material ranges from 37 to 56 nm was observed from XRD. From PLE and PL spectrum the excitation and emission spectra of photoluminescence for Eu3+ doped Li2SrSiO4 were recorded. The prepared Eu3+ doped Li2SrSiO4 phosphor might have application in solid state lighting.

Multicolor tunable emission through energy transfer in Dy3+/Ho3+ co-doped CaTiO3 phosphors with high thermal stability for solid state lighting applications

The exploration of multicolor emitting phosphors with single phase is extremely important for n-UV chip excited LED/WLED’s and multicolor display devices. In this paper, Dy3+, Ho3+ singly doped and Dy3+/Ho3+ co-doped CaTiO3 phosphor materials have been synthesized by solid state reaction method at 1473 K. The synthesized materials were characterized by XRD, FE-SEM, EDX, FTIR, PL and lifetime measurements. The PL emission spectra of Dy3+ doped CaTiO3 phosphors give intense blue and yellow emissions under UV excitation, while the PL emission spectra of Ho3+ doped CaTiO3 phosphor show intense green emission under UV/blue excitations. Further, to get the multicolor emission including white light, Dy3+ and Ho3+ were co-doped simultaneously in CaTiO3 host. It is found that alongwith colored and white light emissions, it also shows energy transfer from Dy3+ to Ho3+ with 367 nm and from Ho3+ to Dy3+ under 362 nm excitations. The energy transfer efficiency is found to be 67.76% and 69.39% for CaTiO3:4Dy3+/3Ho3+ and CaTiO3:3Ho3+/5Dy3+ phosphors, respectively. The CIE color coordinates, CCT and color purity of the phosphors have been calculated, which show color tunability from whitish to deep green via greenish yellow color. The lifetime of 4F9/2 level of Dy3+ ion and 5S2 level of Ho3+ ion is decreased in presence of Ho3+ and Dy3+ ions, respectively. This is due to energy transfer from Dy3+ to Ho3+ ions and vice versa. A temperature dependent photoluminescence studied of CaTiO3:4Dy3+/2Ho3+ phosphor show a high thermal stability (82% at 423 K of initial temperature 303 K) in the temperature range 303–483 K with activation energy 0.17 eV. The PLQY are 30%, 33% and 35% for CaTiO3:4Dy3+, CaTiO3:4Dy3+/2Ho3+ and CaTiO3:3Ho3+ phosphors, respectively. Hence, Dy3+, Ho3+ singly doped and Dy3+/Ho3+ co-doped CaTiO3 phosphor materials can be used in the field of single matrix perovskite color tunable phosphors which may be used in multicolor display devices, n-UV chip excited LED/WLED’s and photodynamic therapy for the cancer treatment.

Multi-color tunable emission of Bi3+,Eu3+ co-doped Ca3LiZnV3O12 phosphors for warm white light-emitting diodes

Bi3+,Eu3+ co-doped Ca3LiZnV3O12 (CLZV) phosphors were manufactured by conventional high-temperature solid-state reaction technique to explore their application for solid-state lighting. Their crystal structure, luminescent properties, energy transfer processes and quantum efficiency were investigated in detailed. CLZV host can be efficiently excited by 345 nm near-ultraviolet light and exhibit self-activating blue emission. When Bi3+ ions are introduced into CLZV, VO43− and Bi3+ can be co-excited by 345 nm light. Benefiting from energy transfer from VO43− to Eu3+ and Bi3+ to Eu3+, multi-color tuning emission from green to yellow can be observed in CLZV:Bi3+,Eu3+ phosphors. Warm white emission was achieved in CLZV:0.015Bi3+,0.01Eu3+ and CLZV:0.015Bi3+,0.02Eu3+ phosphors. Importantly, their internal quantum efficiencies are 35.2 % and 39.6 %, respectively. Our results indicate that CLZV: Bi3+,Eu3+ phosphors might be promising candidates for white light emitting diodes under ultraviolet excitation.

Fabrication and luminescence properties of Al2O3-Ce:LuAG composite phosphor ceramics for solid-state laser lighting

Introducing Al2O3 as a secondary phase into Ce:LuAG phosphor ceramics has been realized by solid-state reaction method, but there is much room for improvement on the ingredient uniformity and performance of Al2O3-Ce:LuAG composite phosphor ceramics (CPCs). In this work, the excess of Al3+ in (Ce,Lu)3Al5O12 was regulated to synthesize a series of Al2O3-Ce:LuAG multiphase powders by the co-precipitation method, and homogeneous Al2O3-Ce:LuAG CPCs (the uniform volume fraction between Al2O3 and Ce:LuAG phases) were obtained by vacuum sintering (1775 °C × 10 h). With an increase in the Al3+ content, the morphology of the multiphase powders changes from small irregular shapes to porous flocs and flakes interwoven, and Lu3Al5O12 phases tend to convert to LuAlO3 phases. When the Al2O3 content is 78–89 mol% in the CPCs, the average grain sizes of Al2O3 are close to those of Ce:LuAG. Among all CPCs with an Al2O3 content of 68–95 mol%, the 85 mol% Al2O3-Ce:LuAG CPCs initially perform the best in terms of both excitation and emission intensity at room temperature, and their photoluminescence intensities only decrease 4.3% from 25 to 225 °C. A solid-state laser lighting device was constructed by using a 450 nm laser source and Al2O3-Ce:LuAG CPCs in a reflection mode. The CPCs with 85 mol% Al2O3 content based on 0.9 W laser diodes (LDs) show the optimum luminous flux (LF) and luminous efficiency (LE) of 244 lm and 266 lm∙W−1, respectively. Additionally, the LF of all CPCs based on LDs continues to increase without showing luminescence saturation when the power density increases from 1 to 20 W mm−2. When the 85 mol% Al2O3-containing CPCs are excited by a 20 W mm−2 LD, the maximum LF reaches 3624 lm, and the LE decreases only by 12.4% (compared to the data under 1 W mm−2 excitation). Al2O3-Ce:LuAG CPCs have excellent luminescence properties and improved thermal stability, which are promising for the application in solid-state laser lighting.

Luminescence and thermal stability of CaLu2-x-yMeyMg2Si3O12:xCe3+ (Me = Sr, Ba) fluorescent materials

White light solid-state lighting applications still face significant challenges due to insufficient efficient and stable red light emitting materials. Therefore, a series of orange-red fluorescent materials, CaLu2-xMg2Si3O12:xCe3+ (CLMS:xCe3+; x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) were prepared in this paper. Luminescence spectra testing revealed that the optimal concentration of Ce3+ ions in the crystal lattice is x = 0.04. At 460 nm excitation, the emission wavelength is approximately 592 nm. To enhance the thermal stability and luminescence performance of CLMS:Ce3+, the CaLu1.96-yMeyMg2Si3O12:0.04Ce3+ (Me = Sr, Ba; y = 0, 0.02, 0.05, 0.10, 0.15, 0.20) fluorescent materials were successfully prepared. It was found that phosphor's fluorescence intensity was enhanced after the introduction of Sr2+ or Ba2+ ions. Meanwhile, the phosphors were tested for thermal stability, and the emission intensities of CLMS:0.04Ce3+, CLMS:0.04Ce3+,0.10Sr2+, and CLMS:0.04Ce3+,0.05Ba2+ phosphors decreased to 77.60%, 85.53%, and 87.63% at 423 K, respectively. This proves that Sr2+ and Ba2+ ions have a positive effect on the thermal stability performance of CLMS:0.04Ce3+ phosphor. Testing of the w-LED devices, the CCT was reduced. The CRI was improved to 80.4 and 81.6 and luminescence efficiency was improved to 107.71 lm/W and 115.04 lm/W after Sr2+ or Ba2+ ions were introduced. In summary, this study demonstrates that CaLu2-x-yMeyMg2Si3O12:xCe3+ (Me = Sr, Ba) is an auspicious fluorescent material with high thermal stability, which is potentially informative for the field of white-light illumination.

Solution-processed CsPbBr3 perovskite LEDs using blended-polymer additives for nearly 100% surface coverage

The all-inorganic perovskite material (CsPbBr3) is a promising light-emitting material due to its narrow color spectrum, wet solution processability, and cost-effectiveness. Despite such advantages, pinholes, poor surface coverage, and stability issues limit widespread applications of perovskite light-emitting devices (PeLEDs) in solid-state lighting applications. The performance of PeLEDs depends strongly on the morphological characteristics of the perovskite layer, with low surface coverage and surface roughness observed to lead to higher current leakage and lower current efficiency. We find that perovskite thin films blended with polymers to form composite layers effectively enhance the thin film’s surface coverage and uniformity, improving performance. We report CsPbBr3 PeLEDs with dual polymer additives, with a 12.1% reduction in the turn-on voltage (Von), a 97.21% reduction in leakage current density, a 200%+ enhancement in maximum brightness, and a 700% increase in power efficiency compared to a control CsPbBr3 device. To study the likely source of these enhancements, we have conducted a comparative film analysis of test and control devices using field-emission scanning electron microscopy and atomic force microscopy. A reduced crystal grain size (∼204nm to ∼101nm) and a nearly 100% (99.79%) surface coverage (compared to 79.53% found for control devices) suggest that the improved overall morphology and surface coverage likely play a significant role in the improved performance. Further, a reduction in surface roughness (∼45%) and the formation of a nearly pinhole-free film are observed to increase yield by 20%.

Design and analysis of a group-III nitride superlattice structure based semiconductor laser diode for blue region emission

The demand for high-power blue laser diodes (LDs) in the range above 2 W has been steadily increasing due to their applications in solid-state lighting, projection displays, high-density optical data storage and underwater communication. However, current designs face limitations in terms of achieving both high power output and efficiency. This work focuses on the design, development and numerical analysis of a blue LD utilizing group-III nitride superlattice structures. The present study aims to overcome design challenges by investigating the fundamental factors affecting the performance of blue LDs based on superlattice InGaN structures through careful device parameter optimization. The results show that our device successfully emits at around 430 nm wavelength and is capable of achieving a differential quantum efficiency of 46.91%, with a maximal optical power output of 2.18 W for 1.71 A of current for a strip width of 15 µm. However, when the strip width is increased to 20 µm, 4.6 W optical power is achieved with 3 A of injection current. Numerical studies are performed with several calibrated physics models and finite-difference time-domain techniques. Our results provide an insight into the potential of using superlattice group-III nitride structures to enhance the performance of blue LDs, opening up new possibilities for high-power and high-efficiency devices in the future.

Microwave-assisted fabrication of Sr2ZnMoO6:Sm2O3 phosphors in TeO2: ZnO: B2O3 glass matrix for high-efficiency solid-state lighting applications

The present work focuses on synthesizing Sr2ZnMoO6:Sm2O3 phosphor-mixed TeO2: ZnO: B2O3 glass by microwave synthesis technique at different times (16, 18, 20, 22, 24 min). These samples, after synthesizing they were characterized through XRD, FTIR, density, molar volume, refractive index, absorption spectra, luminescence properties, and lifetime analysis.The study of crystalline nature was studied using XRD spectra of Sr2ZnMoO6. Absorption spectra were evaluated in the wavelength region between 400 and 1800 nm and found seven peaks, which corresponded with the energy transitions of Sm3+ion from the ground level of 6H5/2 → 6F11/2, 9/2, 7/2, 5/2, 3/2, 6H15/2, and 6F1/2 at 944, 1083, 1238, 1383, 1485 and 1543 nm respectively. The photoluminescence in the wavelength region of 500–750 nm using the excitation wavelength at 403 nm. The emission intensity of the samples increased with sintering time until 20 min after which it decreased. The highest peak was observed at 597 nm, corresponding to 4G5/2 → 6H7/2 (orange) transitions of Sm3+ ion. The luminescence lifetime from the 4G5/2 to 6H7/2 level increased with increasing sintering time until 20 min, which had a lifetime of 0.431–0.711 ms when monitored at λex = 403 nm. The results obtained in photoluminescence properties showed that the samples could be potential candidates for orange light-emitting diodes for solid-state lighting applications.

Double hole transport layers deliver promising-performance in light-emitting diodes based on MAPbBr3 nanocrystals

Perovskite Nanocrystal Light Emitting Diodes (PNC-LEDs) are highly regarded as promising candidates for future solid-state lighting and high-definition display applications. To achieve high-performance LEDs, it is essential to have an emitting layer with a high photoluminescence quantum yield (PLQY) and excellent carrier transport properties, along with a well-optimized device structure. In this work, high performance MAPbBr3 NCs (PLQY>95 %) were synthesized via combination of 4-methoxyphenethylamine and didodecyldimethylammonium bromide, which lead to improved carrier transport of NC emitting layer. Moreover, a double hole transport layers (D-HTL) structure was developed to provide stepwise energy barrier for hole injection, resulting in improved external quantum efficiency (EQE). The green MAPbBr3 PNC-LED with the D-HTL structure exhibited a maximum EQE of 10.7 % and a current efficiency (CE) of 32.5 cd A−1, outperforming the PNC-LED with the conventional single HTL PTAA (EQE 5.8 %, and CE 17.7 cd A−1) by almost 2 times. These findings showcase a rational strategy to enhance PNC-LEDs performance through device structure engineering, particularly when utilizing a high-performance PNC emitting layer.

Realization of orange-red emitting double perovskite structured Sm3+-doped Ba2ZnWO6 nanophosphors: A systematic study of structural, photoluminescence and photometric properties for solid-state lighting applications

Exploring luminescent materials that meet the necessary specifications which can beneficial for solid-state lighting applications has prompted extensive research. In this context, the present article deals with a successful exploration of orange-red emanating double perovskite structured Sm3+ (1–11 mol %) -doped Ba2ZnWO6 nanophosphors synthesized via a self-igniting solution combustion route. The crystallographic studies of the phosphors confirm the cubic phase having Fm̅3m space group. The morphological investigations exhibit non-uniform flaky-type particles with agglomeration. The average optical energy gap of the phosphors is found to be around 3.25 eV. The photoluminescence emission spectra enclosed three distinctive peaks located at around 564, 597, and 644 nm, which are attributed to 4G5/2→6HJ (J = 5/2, 7/2 and 9/2) transitions of Sm3+ ions, respectively. The estimated chroma coordinates (0.5385, 0.4527) are located in the orange-red region of the chromaticity diagram and achieve correlated color temperature values between 1865 and 2783 K with color purity in the range 94.7–98.7 %. The obtained results dominantly certified the suitability of the prepared nanophosphors as a favorable candidate for solid-state lighting applications.

Luminescence properties of ZrO2: Dy3+ phosphor for solid-state lighting applications

Herein, we report Dy3+-activated ZrO2 phosphors synthesized via the sol-gel technique. The structural, morphological, and optical properties of the synthesized powder samples annealed at 900 °C were investigated. The monoclinic phase of the synthesized phosphor was confirmed by recording the X-ray powder diffraction (XRPD) pattern. Ultraviolet–visible analysis was performed for the reflectance and bandgap measurements of the phosphors. Field emission scanning electron microscope and X-ray energy dispersive spectroscopy analyses were used to study the morphology and elemental composition of the phosphors, respectively. The distribution of ions in the undoped and Dy3+-doped samples was confirmed using time-of-flight secondary ion mass spectroscopy. The photoluminescence (PL) behavior of the synthesized phosphors was investigated by recording the excitation and emission spectra. When the synthesized phosphors were exposed to UV light at 353 nm, we observed characteristic blue and yellow Dy3+ PL emissions, corresponding to the transition 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2, respectively. Additionally, we observed low-intensity red and brown-red emission peaks corresponding to 4F9/2 → 6H11/2 and 4F9/2 → 6H9/2. These observations indicate that the non-aqueous sol-gel route, coupled with the suitable post-synthesis heat treatment, resulted in the development of a monophase (monoclinic) zirconia. This makes it a strong candidate for phosphor applications due to its high room temperature stability and efficient characteristic features of the monoclinic phase. These findings strongly suggest that Dy3+-doped ZrO2 can serve as a superior phosphor material for white light-emitting diode applications.

Luminescence and optical thermometry strategy based on emission spectra of Li2Ba5W3O15:Pr3+ phosphors

In this study, a series of Pr3+ ions doped Lithium Barium Tungstate (Li2Ba5W3O15) was synthesized using the conventional high-temperature solid state method. The structure and phase of the phosphors were analysed using X-ray diffraction (XRD) patterns. Fourier Transform Infrared (FT-IR) spectroscopy was used to examine the different vibrational bands present. The optical band gap values of the optimized LBW phosphor and the undoped LBW sample were measured using diffuse reflectance spectra (DRS). Under 319 nm excitation, the photoluminescence (PL) spectra of the Pr3+-activated LBW phosphor exhibited strong visible blue and reddish emissions at 488 nm and 647 nm respectively corresponding to the 3P0 → 3H4 and 3F2 transitions of the Pr3+ ions. The evaluated CIE color chromaticity coordinates of the as-prepared LBW:Pr3+ phosphors lie within the white region. The temperature-dependent PL (TDPL) measurement demonstrated relatively good thermal stability for the synthesized phosphor. Moreover, the fluorescence intensity ratio (FIR) was used to analyze the optical sensing properties of the LBW:Pr1.0 phosphor. A maximum relative sensitivity (Sr) of 1.03 % K−1indicated the potential of these phosphors for optical thermometry applications. A double exponential trend with decreasing lifetime was observed in the PL decay data at 647 nm emission (λem) under 319 nm excitation (λex), with an increase in the Pr3+ ions concentration in the host matrix. In conclusion, the investigations conducted demonstrate that the Pr3+ ions doped LBW phosphors show great potential for applications in solid-state lighting and optical thermometry. Its emission characteristics, thermal stability, and optical sensing capabilities establish it as a suitable candidate for these applications.

Organic Electronics-Microfluidics/Lab on a Chip Integration in Analytical Applications.

Organic electronics (OE) technology has matured in displays and is advancing in solid-state lighting applications. Other promising and growing uses of this technology are in (bio)chemical sensing, imaging, in vitro cell monitoring, and other biomedical diagnostics that can benefit from low-cost, efficient small devices, including wearable designs that can be fabricated on glass or flexible plastic. OE devices such as organic LEDs, organic and hybrid perovskite-based photodetectors, and organic thin-film transistors, notably organic electrochemical transistors, are utilized in such sensing and (bio)medical applications. The integration of compact and sensitive OE devices with microfluidic channels and lab-on-a-chip (LOC) structures is very promising. This survey focuses on studies that utilize this integration for a variety of OE tools. It is not intended to encompass all studies in the area, but to present examples of the advances and the potential of such OE technology, with a focus on microfluidics/LOC integration for efficient wide-ranging sensing and biomedical applications.