Lighting Applications Research Articles

Study of hydrate nucleation and growth aided by micro-nanobubbles: Probing the hydrate memory effect

Gas hydrates have been considered promising in gas storage, gas separation, and water desalination. The hydrates' technical application is affected by the long kinetics time. Of interest is gas hydrates show strong facilitation in dissociated water containing a high concentration of micro-nanobubbles. Here, it was discovered that the nano-particles present in the dissociated water were identified as nano-bubbles, characterized by nanoparticle track analyzer and infrared spectrum. The presence of bubbles increased the nucleation probability, likely attributed to the provision of nucleation sites. Results indicated that the ability of facilitation was related to the nanobubble types: the bubble solution with the same guest molecules exhibited similar facilitation to dissociated water; specifically, the average induction time was shortened by 27.48 %, the nucleation probability was increased by 50 % compared to deionized water. Moreover, the time hydrate filled the field of view with high bubble concentration was reduced by 60 % compared with low bubble concentration. The facilitation effect mechanism could be related to the presence of gas-dense regions inside the bubbles, based on the Raman results. This finding may offer valuable insights for the application of hydrate-based energy storage technology and shed light on the potential role of bubbles in causing memory effects.

Differences of secondary metabolites content in Kasturi Mango (Mangifera casturi Kosterm.) from South Kalimantan by the application of artificial light using light emitting diode

Differences of secondary metabolites content in Kasturi Mango (<i>Mangifera casturi</i> Kosterm.) from South Kalimantan by the application of artificial light using light emitting diode

Application of Red and Blue LED Light on Cultivation and Postharvest of Tomatoes (Solanum lycopersicum L.).

Currently, light-emitting diode (LED) technology has produced a more energy-efficient and versatile technology as an artificial lighting system that can be applied in the agricultural sector. Artificial lighting technology has been proven to be effective in increasing the production of agricultural products, especially horticultural commodities. As one of the primary horticulture commodities, tomatoes are the most common crop produced in controlled environments with LED artificial lighting. The focus of this study is to describe the application of LED lights in tomato cultivation and postharvest. We provide an amalgamation of the recent research achievements on the impact of LED lighting on photosynthesis, vegetative growth, flowering, production, and postharvest of tomatoes. Red-blue (RB) lighting induces photosynthesis; increases the content of chlorophyll a, chlorophyll b, and carotenoids in tomato leaves; regulates vegetative growth in tomatoes; and increases the production of tomatoes. In postharvest tomatoes, blue LED lighting treatment can slowly change the color of the tomato skin to red, maintain hardness, and increase shelf life. Future research may be carried out on the effect of LED artificial lighting on tomatoes' phytochemical, antioxidant and other crucial nutritional content. Different LED wavelengths can be explored to enhance various bioactive compounds and health-promoting components.

Utilizing weakly donor-acceptor ternary π-conjugated architecture to achieve single-component white luminescence and stimulus-responsive room-temperature phosphorescence.

Purely organic room-temperature phosphorescence (RTP) has garnered substantial attention for its delayed emission, environmental sensitivity, and potential diverse applications. However, the quest for high-performance RTP materials has always been a challenge. In this study, we introduce novel weakly donor-acceptor (D-A) ternary π-conjugated architecture to construct an efficient RTP system. The strategy utilizes synergistic effects of the analogous El-Sayed rule, halogen-free heavy-atom effect, reduction of the singlet-triplet energy gap, and manipulation of flexible molecular conformation. A remarkable enhancement in the phosphorescence-to-fluorescence ratio was achieved, elevating from 0.4 in carbazole to 35.2 in DBTDBTCZ. Furthermore, the RTP system demonstrates single-component white luminescence, yielding warm and cool white colors. Intriguingly, we unveil the novel position-dependent heavy-atom effects, discerningly promoting intersystem crossing or phosphorescence decay. Benefiting from efficient RTP, multifunctional applications of real-time humidity monitoring, oxygen sensing, anti-counterfeiting labeling, and white lighting are demonstrated.

The emergence and prospects of carbon dots with solid-state photoluminescence for light-emitting diodes.

The significant features of carbon dots (CDs), such as bright and tunable photoluminescence, high thermal stability, and low toxicity, endow them with tremendous potential for application in next generation optoelectronics. Despite great progress achieved in the design of high-performance CDs so far, the practical applications in solid-state lighting and displays have been retarded by the aggregation-caused quenching (ACQ) effect ascribed to direct π-π interactions. This review provides a comprehensive overview of the recent progress made in solid-state CD emitters, including their synthesis, optical properties and applications in light-emitting diodes (LEDs). Their triplet-excited-state-involved properties, as well as their recent advances in phosphor-converted LEDs and electroluminescent LEDs, are mainly reviewed here. Finally, the prospects and challenges of solid-state CD-based LEDs are discussed with an eye on future development. We hope that this review will provide critical insights to inspire new exciting discoveries on solid-state CDs from both fundamental and practical standpoints so that the realization of their potential in optoelectronic areas can be facilitated.

Synergistic interaction of multi-functional additives at the buried interface for efficient blue perovskite light-emitting diodes

The synergistic effect of the doping strategy of basic amino acid salts at the interface enables the simultaneous modification of PEDOT:PSS and the bottom interface of the perovskite film to achieve efficient sky-blue PeLEDs.

Practice of green chemistry strategies in synthetic organic chemistry: a glimpse of our sincere efforts in green chemistry research.

This feature article summarises our recent contributions (2019-2023) in designing and developing a handful of promising organic transformations for accessing several diversely functionalised biologically relevant organic scaffolds, following the green chemistry principles, particularly focusing on the application of low-energy visible light, electrochemistry, ball-milling, ultrasound, and catalyst- and additive-free synthetic strategies.

Novel Eu3+-activated Ca3Ga2Ge4O14 red-emitting phosphors with high quantum efficiency for plant growth lighting and white LEDs.

In recent years, rare-earth-based phosphors for near-ultraviolet (NUV)-triggered white light emitting diodes (w-LEDs) have become a research hotspot. However, it is still not possible to obtain phosphors with high quantum yield, excellent color purity and multiple applications. Hence, a series of novel Eu3+-activated Ca3Ga2Ge4O14 (CGG) red-emitting phosphors with high quantum efficiency, excellent color purity and good thermal stability were prepared by a high-temperature solid-phase method. All the CGG:Eu3+ phosphors emitted dazzling red emission with excitation at 394 nm. The optimal Eu3+ doping concentration of compounds was 12% with an excellent color purity of 97.89%, and the concentration quenching mechanism was investigated as dipole-dipole interactions. Meanwhile, the synthetic samples exhibited good thermal stability with the activation energy of 0.26 eV. Remarkably, the internal quantum yield of the prepared phosphors reaches 94.26%. Furthermore, the emission spectra of the prepared red-LEDs overlap considerably with the absorption spectra of PR and PFR required for plant growth. The w-LED device emits warm white light with a high color rendering index of 91.64 and an appropriate correlated color temperature of 4808 K. These excellent luminescence properties indicate that the prepared CGG:Eu3+ phosphors exhibit extensive potential for applications in plant growth lighting and white LEDs.

Results of EEBL Simulation for the Smartphone VANET

The Smartphone VANET (Vehicle Ad-Hoc NETwork) is a novel concept for VANET using smartphones as On Board Units. VANET technology has great potential to reduce injuries and fatalities on our roadways. The smartphone presents many disadvantages compared to dedicated VANET hardware. In order to ensure that the smartphone VANET is feasible for safety applications, an Electronic Brake Light (EEBL) application has been developed for it. In this paper, we test this application in Veins VANET simulator We test the crash reduction and networking capabilities of the EEBL, and present the results.

The Investigation of Dimensional, Form and Orientation Accuracy of Polymer Gears Prepared by Additive Manufacturing

Among the additive manufacturing techniques Fused Deposition Modeling (FDM) is a widely used process, due to its rapid development in the recent years, and its consequent drop in price. 3D printing has multiple process parameters, which affect the dimensional, form, and orientation accuracy, and thus the usability of the final product. In this work the effects of layer thickness, printing speed, and infill on the dimensional and geometric deviations were studied with a 3 factor Box-Behnken experimental design. The measured deviations were within the tolerance range specified by the standards. Based on this, it can be stated that 3D printing is a promising gear manufacturing technology for light and medium load applications.

Colloidal synthesis of emission-tunable Cu-doped Zn–In–Se/ZnSe core/shell nanocrystals for lighting and bioimaging applications

Herein, environmentally benign CuI:Zn–In–Se/ZnSe core/shell luminescent inorganic nanocrystals (NCs) were synthesized via a phosphine-free one-pot, two-step organometallic approach with good colloidal quality.

Sub-wavelength focused light and optical trapping application based on two-mode interference from an optical micro-/nanofiber

The ability to focus light on a subwavelength scale is essential in modern photonics. Optical microfiber-based sub-wavelength focusing will allow a miniaturized, flexible and versatile tool for many applications such as biomedical imaging and optomechanics. For a separate mode exited from an optical micro-/nanofiber endface, the photons will experience significant diffraction into the free space. This situation can be changed by incorporating two-mode interference along with the specific spatial distributions of both &lt;i&gt; &lt;b&gt;E&lt;/b&gt; &lt;/i&gt;-field amplitude and phase. Herein we report a novel approach to realizing sub-wavelength focusing based on the two-mode interference exited from an optical microfiber endface. By utilizing specific distributions of &lt;b&gt;&lt;i&gt;E&lt;/i&gt;&lt;/b&gt; -field amplitude and phase of two interacting optical modes, interference field patterns with a single focus (e.g., via a two-mode set of HE&lt;sub&gt;11&lt;/sub&gt; and HE&lt;sub&gt;12&lt;/sub&gt;) or multiple foci (e.g., via a two-mode set of HE&lt;sub&gt;11&lt;/sub&gt; and HE&lt;sub&gt;31&lt;/sub&gt;) can be obtained. Then, it is proved that the constructed foci will readily facilitate and selective trapping of nanoparticles. Circular polarization of optical mode is utilized in order to bring in angular symmetry of sub-wavelength focusing patterns compared with linear polarized optical modes. Our simulation results show that the smallest focal spot produced from the EH&lt;sub&gt;11&lt;/sub&gt; and HE&lt;sub&gt;12&lt;/sub&gt; mode interference has a full width at half-maximum (FWHM) of ~ 348 nm (i.e. 0.65&lt;i&gt;λ&lt;/i&gt;). Such a subwavelength focusing field is applied to the optical trapping of an 85 nm-diameter polystyrene nanosphere. Further calculation reveals that the stable trapping can be fulfilled with axial and transverse trap stiffness of 11.48 pN/(μm·W) and 64.98 pN/(μm·W), as well as axial and transverse potential well of 101 &lt;i&gt;k&lt;/i&gt;&lt;sub&gt;B&lt;/sub&gt;T/W and 641 &lt;i&gt;k&lt;/i&gt;&lt;sub&gt;B&lt;/sub&gt;T/W via two-mode interference of HE&lt;sub&gt;11&lt;/sub&gt; and HE&lt;sub&gt;12&lt;/sub&gt;. These values demonstrate the great improvement over conventional tapered fibers. Further investigations show that different foci, via a two-mode set of HE&lt;sub&gt;11&lt;/sub&gt; and HE&lt;sub&gt;31&lt;/sub&gt;, exhibit unlike trap stiffness and potential wells, justifying the potential for nanoparticle size sorting. Based on the flexible all-fiber device, this subwavelength focusing strategy by two-mode interference may find promising applications in optical manipulation, superresolution optical imaging, data storage and nanolithography.

Unraveling the excitonics of light emission from metal-halide perovskite quantum dots.

Metal halide semicondictor perovskites have been under intense investigation for their promise in light absorptive applications like photovoltaics. They have more recently experienced interest for their promise in light emissive applications. A key aspect of perovskites is their glassy, ionic lattice that exhibits dynamical disorder. One possible result of this dynamical disorder is their strong coupling between electronic and lattice degrees of freedom which may confer remarkable properties for light emission such as defect tolerance. How does the system, comprised of excitons, couple to the bath, comprised of lattice modes? How does this system-bath interaction give rise to novel light emissive properties and how do these properties give insight into the nature of these materials? We review recent work from this group in which time-resolved photoluminescence spectroscopy is used to reveal such insights. Based upon a fast time resolution of 3 ps, energy resolution, and temperature dependence, a wide variety of insights are gleaned. These insights include: lattice contributions to the emission linewidths, multiexciton formation, hot carrier cooling, excitonic fine structure, single dot superradiance, and a breakdown of the Condon approximation, all due to complex structural dynamics in these materials.

The unique luminescent properties and enhanced thermal stability of a novel all-inorganic perovskite CsCaCl3:Mn2+ for solid-state lighting applications

This paper addresses the development and characterization of a novel all-inorganic perovskite crystal, CsCaCl3:Mn2+, which presents remarkable potential for advanced white-light LED applications.

Efficiency droop in zincblende InGaN/GaN quantum wells.

The decrease in emission efficiency with increasing drive current density, known as 'droop', of c-plane wurtzite InGaN/GaN quantum wells presently limits the use of light-emitting diodes based on them for high brightness lighting applications. InGaN/GaN quantum wells grown in the alternative zincblende phase are free of the strong polarisation fields that exacerbate droop and so were investigated by excitation-dependent photoluminescence and photoreflectance studies. Polarisation-resolved measurements revealed that for all excitation densities studied the emission from such samples largely originates from similar microstructures or combinations of microstructures that form within the quantum well layers. Emission efficiency varies significantly with excitation at 10 K showing that non-radiative recombination processes are important even at low temperature. The onset of efficiency droop, as determined by photomodulated reflection measurements, occurred at a carrier density of around 1.2 × 1020 cm-3 - an order of magnitude greater than the value reported for a reference wurtzite quantum well sample using the same method. The high carrier density droop onset combined with the much shorter carrier lifetime within zincblende InGaN/GaN quantum wells indicate they have the potential to effectively delay efficiency droop when used in GaN based light-emitting diodes. However, the material quality of the quantum well layers need to be improved by preventing the formation of microstructures within these layers, and the importance of the role played by non-radiative centres in the QW layer needs to be elucidated, to fully realise the material's potential.

Active control of an electromagnetically induced transparency analogue in a coupled dual bound states in the continuum system integrated with graphene.

Electronically induced transparency (EIT) is a coherent optical phenomenon that induces interference within atoms, allowing certain specific frequencies of light to pass through atomic media without being absorbed. However, EIT systems face challenges related to narrow transparency windows and precise control of slow light. We propose an interference structure based on a coupled dual bound states in the continuum (BIC) system to emulate the EIT-like effect. By integrating quasi-BIC (bright mode) with BIC (dark mode), our design successfully achieves an EIT-like effect in a narrow bright mode with a full width at half maximum (FWHM) of less than 1 nm. Its notable features are the bright mode's wide tunability achieved through structural parameter adjustment and a significant group delay of up to 14.43 ps. Additionally, integrating graphene into the BIC structure introduced a form of active tunability akin to the EIT-like effect. We numerically calculate the coupling structure, and its intrinsic mechanism is analyzed. Analysis based on coupled-mode theory confirms that this active modulation primarily stems from changes in the BIC structure's loss. Due to its special frequency selectivity and insensitivity to the polarization of the light source, this narrow-band EIT-like structure is particularly suitable for high-precision optical sensing and spectroscopy. The significant group delay of this structure enhances the interaction between light and matter, improving the accuracy and efficiency of optical signal control and data transmission, opening up new avenues for slow light applications and making significant progress in the development of active tunable optical switches and modulators.

Achieving high brightness and thermally stable far-red luminescence via ultrathin phosphor-glass composites engineering

Far-red (FR) emission ( &gt; 700 nm) with high efficiency and excellent thermal stability is in great demand for solid-state lighting applications in health illumination. However, currently used FR materials...

Promoting structural distortion to enhance the crystal field strength of Mn(II) in tetrahedral bromide for near-unity yellow emission.

Two zero-dimensional hybrid manganese bromide polymorphs ((DMAPH)2MnBr4) exhibit single-crystal to single-crystal phase transformation, accompanied by an increase in MnBr4 tetrahedral bond angle variance (σ2). This structural change leads to an emission redshift due to enhanced crystal field strength, achieving yellow emission with near-unity quantum yield, which highlights its potential for solid-state lighting applications.

Sustainable next-generation color converters from P. harmala seed extracts for solid-state lighting.

Traditional solid-state lighting heavily relies on color converters, which often have a significant environmental footprint. As an alternative, natural materials such as plant extracts could be employed if their low quantum yields (QYs) in liquid and solid states were higher. With this motivation, here, we investigate the optical properties of aqueous P. harmala extract, develop efficient color-converting solids through a cost-effective and environmentally friendly method, and integrate them with light-emitting diodes (LEDs). To achieve high-efficiency solid hosts for P. harmala-based fluorophores, we optically and structurally compare two crystalline and two cellulose-based platforms. Structural analyses reveal that sucrose crystals, cellulose-based cotton, and paper platforms enable a relatively homogeneous distribution of fluorophores compared to KCl crystals. Optical characterization demonstrates that the extracted solution and the extract-embedded paper possess QYs of 75.6% and 44.7%, respectively, whereas the QYs of the cotton, sucrose, and KCl crystals remain below 10%. We demonstrated that the paper host with the highest efficiency causes a blueshift in the P. harmala fluorescence, whereas the cotton host induces a redshift. We attribute this to the passivation of nonradiative transitions related to the structure of the hosts. Subsequently, as a proof-of-concept demonstration, we integrate the as-prepared efficient solids of P. harmala for the first time with a light-emitting diode (LED) chip to produce a color-converting LED. The resulting blue-emitting LED achieves a luminous efficiency of 21.9 lm Welect -1 with CIE color coordinates of (0.139, 0.070). These findings mark a significant step toward the utilization of plant-based fluorescent biomolecules in solid-state lighting, offering promising environmentally friendly organic color conversion solutions for future lighting applications.

Influence of barium substitution on the physical, thermal, optical and luminescence properties of Sm3+-doped metaphosphate glasses for reddish orange light applications.

Our present study focuses on examining the thermal, structural and luminescent characteristics of sodium barium metaphosphate glasses doped with Sm3+. Glass samples with molar compositions (100 - y)[(50P2O5)-(50-xNa2O)-(xBaO)]-ySm2O3, where x = 20, 25, 30, 35, 40 and y = 0.3 and 1% were first synthesized by conventional melt quenching and later dehydroxylated under a constant N2 flow to ensure final glasses with a very high degree of chemical and optical homogeneity and free of water. Upon the addition of BaO and Sm2O3, refractive index, molar mass, density, glass transition temperature and dilatometric softening temperature exhibited an increase, whereas the coefficient of thermal expansion showed a decrease. The FTIR spectra analysis reveals a network depolymerization that intensifies with rising BaO concentration, ultimately transitioning from a modifier oxide to a glass-forming element, at higher BaO concentrations. All doped samples exhibited prominent absorption bands in the visible (VIS) and near-infrared (NIR) regions, as revealed by the optical absorption spectra. The Na2O modifier demonstrated greater influence on Sm3+ emission compared to BaO, a phenomenon that can explained by the moderation of the local ligand field strength resulting from this substitution. With an increase in Sm2O3 concentration from 0.3 to 1 mol%, the experimental lifetimes of the 4G5/2 level decrease, primarily attributed to the presence of energy transfer mechanisms. A discussion of Judd-Ofelt parameter analysis and glass radiation properties will be presented.