Blue Light Emission Research Articles

Exploring 0D lead-free metal halide with highly efficient blue light emission and high-sensitivity photodetection.

Environmentally friendly and highly efficient blue luminescent materials are an unremitting pursuit in the optoelectronic field. Herein, we assembled a new 0D lead-free metal halide of (F-PPA)ZnBr4, which exhibits narrow blue light emission with a remarkable PLQY of 50.15%, high stability and high detection sensitivity toward UV light. These results indicate the potential for the application of low-dimensional zinc-based halides in multiple optoelectronic devices.

Zero-dimensional organic–inorganic hybrid zinc halide with stable broadband blue light emissions

A series of zero-dimensional zinc halide materials based on [ZnX4]2− tetrahedra are prepared, which exhibit intense broadband blue light emission.

Blue light emission enhancement and robust pressure resistance of gallium oxide nanocrystals.

Exploration of pressure-resistant materials largely facilitates their operation under extreme conditions where a stable structure and properties are highly desirable. However, under extreme conditions, such as a high pressure over 30.0 GPa, fluorescence quenching generally occurs in most materials. Herein, pressure-induced emission enhancement (PIEE) by a factor of 4.2 is found in Ga2O3 nanocrystals (NCs), a fourth-generation ultrawide bandgap semiconductor. This is mainly attributed to pressure optimizing the intrinsic lattice defects of the Ga2O3 nanocrystals, which was further confirmed by first-principles calculations. Note that the bright blue emission could be stabilized even up to a high pressure of 30.6 GPa, which is of great significance in the essential components of white light. Notably, after releasing the pressure to ambient conditions, the emission of the Ga2O3 nanocrystals can completely recover, even after undergoing multiple repeated pressurizations. In addition to stable optical properties, synchrotron radiation shows that the Ga2O3 nanocrystals remain in the cubic structure described by space group Fd3m upon compression, demonstrating the structural stability of the Ga2O3 nanocrystals under high pressure. This study pays the way for the application of oxide nanomaterials in pressure anti-counterfeiting and pressure information memory devices.

Anti-thermal quenching of luminescence in Y2W3O12:Yb3+/RE3+ (RE = Er/Ho/Tm) and its temperature sensing application.

Herein, a series of Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors is prepared via a solid-state reaction. The upconversion and downshift luminescence properties of the phosphors were investigated under an excitation of 980 nm. The bright blue light emission from Tm3+ ion and the green and red light emissions from Ho3+(Er3+) ions were observed. The near-infrared light intensity of NIR-I (Tm3+, ∼850 nm), NIR-II (Er3+: ∼1550 nm; Tm3+: ∼1783 nm) and NIR-III (Ho3+: ∼2050 nm) were analyzed. In particular, the dramatic thermal enhancement phenomenon in visible and NIR regions was exhibited by the Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors. Among them, the green light intensity of Er3+ ions increased 26.77 times, from 303 to 573 K. The NIR-II emission band (∼1783 nm) intensity of Tm3+ ions at 533 K increased 168.7 times compared to that at 313 K. The possible thermal enhancement mechanism is illustrated by the negative thermal expansion (NTE) and Frenkel defect of the Y2W3O12 host. Finally, the optical temperature sensing performances of Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) samples are investigated according to the luminescence intensity dependence relationship on temperature. The maximum value of SR reached 4.24% K-1 at 353 K for Y2W3O12:10%Yb3+/0.6%Ho3+ phosphor. The results indicate that the Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors possess anti-thermal quenching properties and are suitable for developing optical temperature sensors.

Water-Stable Zero-Dimensional Hybrid Zinc Halide Modulated by π-π Interactions: Efficient Blue Light Emission and Third-Order Nonlinear Optical Response

Achieving multifunctional optimization of halide optical materials through the precise modulation of intermolecular interactions is highly significant, yet it faces considerable challenges. Here, we propose a strategy of π-π interactions...

Broadband blue light emissions of one-dimensional hybrid Cu(I) halides with ultrahigh anti -water stability.

Low-dimensional organic-inorganic hybrid lead halide perovskites have attracted much interest in solid-state lighting and displays, but the toxicity and instability of lead halide are obstacles to their industrial applications, which must be overcome. As an alternative, Cu(I)-based hybrid metal halides have emerged as a new type of luminescent material owing to their diversified structure, adjustable luminescence, low toxicity and low cost. Herein, we report three one-dimensional (1D) hybrid Cu(I)-based halides with the general formula ACu2Br4 (A = [(Me)4-Pipz]2+ and [BuDA]2+ and [TMEDA]2+). These 1D hybrid Cu(I) halides display stable broadband blue emission with maximum emission peaks in the range of 445-474 nm and the highest photoluminescence quantum yield of 37.8%. Furthermore, in-depth experimental and theoretical investigations revealed that the broadband blue emissions originate from the radiative recombination of self-trapped excitons. Most importantly, there is no structural degradation and attenuation of emission intensity even after continuously soaking these halides in water for at least two months, demonstrating their ultra-high anti-water stability. Hirshfeld surface analysis shows that a large number of weak hydrogen bonds can protect the inorganic skeleton from degradation due to water. This work provides a new strategy for the design of water-stable Cu(I)-based halides with efficient blue emission and wide potential applications in humid environments.

Highly efficient blue luminescence from stable lead-free Cu-doped Rb2LiBiBr6 double perovskites

Highly efficient three-dimensional (3D) lead-free halide perovskites that produce blue light emission with outstanding stability have attracted global research attention.

Hubungan Gelombang Cahaya Lampu dan Cahaya Biru dengan Kualitas Tidur Remaja Dewasa

Sleep is a crucial part of the human circadian cycle. The quality and quantity of sleep significantly influence various aspects of health, both physical and psychological. The hormone melatonin, which plays a vital role in sleep regulation, is produced as the intensity of light received by the eyes decreases. Currently, the use of lights and electronic devices emitting blue light is widespread, especially among teenagers to adults. This blue light can interfere with the production of melatonin, potentially disrupting sleep quality and patterns. In this age group, most are active students with busy schedules. This study uses a sequential explanatory design approach, combining quantitative and qualitative questionnaires to collect data and measure the impact of light on sleep duration and patterns. The respondents of this study were 71 people, coming from various universities and different study programs in Bandung City, ranging in age from 18 to 25 years. The research data results show that 38.6% of respondents experience sleep disturbances when the light is on, impacting sleep quality. Conversely, sleep quality improvement occurs in 81.4% of respondents when sleeping with the light off. The use of night mode on electronic devices, designed to reduce blue light emissions, positively impacts sleep quality, as felt by 38% of the 67.1% of respondents who use the night mode feature.

Study of structural, luminescence and Judd-Ofelt calculations for Ce3+ doped ZnS phosphors for display applications

This paper discusses the luminescence properties of novel Zn(1-x)S: xCe3+ (x = 0, 0.01, 0.02, 0.03, 0.1, 0.2 and 0.3) prepared via conventional solid-state reaction method at low temperature. The XRD results revealed that all synthesized phosphors have hexagonal structure. The strain was calculated using size-strain plot (SSP) method. The FTIR study identifies the various vibrational modes present in the synthesized phosphors. The structural and luminescence characteristics of the prepared samples were enhanced by Ce3+ substitution. The optical band gap energies were found to be decreasing with Ce3+ substitution. The optimal Ce3+ content for superior blue emission is found to be x = 10 mol %. The blue emission supports the incorporation of Ce3+ ions within the ZnS lattice, which is again confirmed by Ω2, Judd-Ofelt intensity parameter. The high value of Ω2 indicates the symmetry of site occupies of Ce3+ ions are lower. The obtained critical distance of energy transfer between Ce3+ ions is calculated to be 6.3095 Å, which implies that the exchange interaction mechanism is a multipolar exchange. The high efficiency, branching ratio, stimulated cross section and the optical parameters indicate that the prepared phosphor materials have efficient blue light emission for display applications.

Blue emitting exciplex for yellow and white organic light-emitting diodes

White organic light-emitting diodes (WOLEDs) have several desirable features, but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures. Herein, we investigate a standard blue emitting hole transporting material (HTM) N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and its exciplex emission upon combining with a suitable electron transporting material (ETM), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ). Blue and yellow OLEDs with simple device structures are developed by using a blend layer, NPB:TAZ, as a blue emitter as well as a host for yellow phosphorescent dopant iridium (III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate (PO-01). Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units. The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer (CGL). Judicious choice of the spacer prevents exciton diffusion from the blue emitter unit, yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation. This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission. The overall white light emission properties are enhanced, achieving CIE coordinates (0.36, 0.39) and color temperature (4643 K) similar to daylight. Employing intermolecular exciplex emission in OLEDs simplifies the device architecture via its dual functionality as a host and as an emitter.Graphical abstract

Single-crystalline GaN microdisk arrays grown on graphene for flexible micro-LED application

We report the growth of single-crystalline GaN microdisk arrays on graphene and their application in flexible light-emitting diodes (LEDs). Graphene layers were directly grown on c-sapphire substrates using chemical vapor deposition and employed as substrates for GaN growth. Position-controlled GaN microdisks were laterally overgrown on the graphene layers with a micro-patterned SiO2 mask using metal–organic vapor-phase epitaxy. The as-grown GaN microdisks exhibited excellent single crystallinity with a uniform in-plane orientation. Furthermore, we fabricated flexible micro-LEDs by achieving heteroepitaxial growth of n-GaN, In x Ga1−x N/GaN multiple quantum wells, and p-GaN layers on graphene-coated sapphire substrates. The GaN micro-LED arrays were successfully transferred onto bendable substrates and displayed strong blue light emission under room illumination, demonstrating their potential for integration into flexible optoelectronic devices.

EE640 The Impact of Blue-Light Emitting Device on the Loss of Productivity From COVID-19 in North Carolina

EE640 The Impact of Blue-Light Emitting Device on the Loss of Productivity From COVID-19 in North Carolina

Review of Low-Dimensional Nanomaterials for Blue-Light Emission

Review of Low-Dimensional Nanomaterials for Blue-Light Emission

Machine learning assisted discrimination and detection of antibiotics by using multicolor microfluidic chemiluminescence detection chip

The fabrication of multicolor chemiluminescence (CL) sensing chip for the discrimination and detection of multianalytes remains a great challenge. Herein, machine learning assisted multicolor microfluidic CL detection chip for the identification and concentration prediction of antibiotics was presented. Firstly, a three-channel microfluidic CL detection chip was fabricated. The three detection zones of the microfluidic detection chip were modified with CL catalyst Co(II) and different CL reagents including luminol, luminol mixed with fluorescein, and luminol mixed with phloxine B, respectively. Strong blue, green and pink-purple colored light emissions can be generated from the three detection zones in the presence of H2O2 solution. The three multicolor CL emissions show different degrees of reduce in intensity and change in color in the presence of different antibiotics, including diethylstilbestro (DES), metronidazole (MNZ), kanamycin (KAN), isoniazide (INH), and ceftiofur sodium (CS), resulting in distinct fingerprint-like response patterns. The red (R), green (G), blue (B) and gray scale values of the three multicolor light emissions were extracted and ten characteristic sensing parameters were chosen to obtain multicolor CL response database. Then, machine learning assisted data analysis were carried out. The five antibiotics can be facilely classified by using principal component analysis (PCA) and hierarchical clustering analysis (HCA), and further quantified by using deep neural networks (DNN) algorithm. Good results were obtained for identification of binary antibiotic mixtures, spiked antibiotics in water samples, and unknown antibiotic samples. Satisfied results were obtained for concentration prediction of antibiotics. This work provides a simple machine learning assisted and multicolor microfluidic CL detection chip based CL sensing strategy for discrimination and quantitative detection of multiple analytes.

A multifunctional optoelectronic device based on 2D material with wide bandgap

Low-dimensional materials exhibit unique quantum confinement effects and morphologies as a result of their nanoscale size in one or more dimensions, making them exhibit distinctive physical properties compared to bulk counterparts. Among all low-dimensional materials, due to their atomic level thickness, two-dimensional materials possess extremely large shape anisotropy and consequently are speculated to have large optically anisotropic absorption. In this work, we demonstrate an optoelectronic device based on the combination of two-dimensional material and carbon dot with wide bandgap. High-efficient luminescence of carbon dot and extremely large shape anisotropy (>1500) of two-dimensional material with the wide bandgap of >4 eV cooperatively endow the optoelectronic device with multi-functions of optically anisotropic blue-light emission, visible light modulation, wavelength-dependent ultraviolet-light detection as well as blue fluorescent film assemble. This research opens new avenues for constructing multi-function-integrated optoelectronic devices via the combination of nanomaterials with different dimensions.

Application and Research Status of Long-Wavelength Fluorescent Carbon Dots.

This article discusses the application and research status of long-wavelength fluorescent carbon dots. Currently, there are two main methods for synthesising carbon dots (CDs), either from top to bottom, according to the bulk material, or from bottom to top, according to the small molecules. In previous research, mainly graphite and carbon fibres were used as raw materials with which to prepare CDs, using methods such as arc discharge, laser corrosion, and electrochemistry. These preparation methods have low quantum efficiencies and afford CDs that are limited to blue short-wavelength light emissions. With advancing research, the raw materials used for CD preparation have expanded from graphite to biomaterials, such as strawberry, lime juice, and silkworm chrysalis, and carbon-based molecules, such as citric acid, urea, and ethylenediamine (EDA). The preparation of CDs using carbon-based materials is more rapid and convenient because it involves the use of microwaves, ultrasonication, and hydrothermal techniques. Research on developing methods through which to prepare CDs has made great progress. The current research in this regard is focused on the synthesis of CDs, including long-wavelength fluorescent CDs, with a broader range of applications.

A High-Efficiency Deep Blue Emitter for OLEDs with a New Dual-Core Structure Incorporating ETL Characteristics.

In this study, we introduced the weak electron-accepting oxazole derivative 4,5-diphenyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)oxazole (TPO) into both anthracene and pyrene moieties of a dual core structure. Ultimately, we developed 2-(4-(6-(anthracen-9-yl)pyren-1-yl)phenyl)-4,5-diphenyloxazole (AP-TPO) as the substitution on the second core, pyrene, and 4,5-diphenyl-2-(4-(10-(pyren-1-yl)anthracen-9-yl)phenyl)oxazole (TPO-AP) as the substitution on the first core, anthracene. Both materials exhibited maximum photoluminescence wavelengths at 433 and 443 nm in solution and emitted deep blue light with high photoluminescence quantum yields of 82% and 88%, respectively. When used as the emitting layer in non-doped devices, TPO-AP outperformed AP-TPO, achieving a current efficiency of 5.49 cd/A and an external quantum efficiency of 4.26% in electroluminescence. These materials introduce a new category of deep blue emitters in the organic light-emitting diodes field, combining characteristics related to the electron transport layer.

Highly efficiency blue emissive from Bi3+ ions in zero-dimensional organic bismuth halide for white LED applications

Zero-dimensional organic-inorganic metal halides (OMHs) attract increasing interest in the fabrication of light-emitting diodes because of their broad emission band and high photoluminescence quantum yield. Thus, almost all OMHs showed green and yellow emissions, while blue was rarely reported. The luminescence mechanism of OMHs was attributed to the self-trapped excitons (STEs), no matter the similar performances between STEs and translations from energy levels of ns2 ions (Sb3+, Bi3+, and Te4+ ions). In this work, zero-dimensional organic tetraphenylphosphonium bismuth chloride TPP2BiCl5 (C48H40P2BiCl5, abbreviated as TBC, TPP=tetraphenylphosphonium.) was synthesized via the antisolvent method The obtained TBC showed the highest efficiency (58%) in blue light emission at 480 nm. While most of the OMHs function according to the STE mechanism, the emission of TBC was confirmed to originate from the 3P1-1S0 transition of Bi3+ ions. The white light-emitting diodes (WLEDs) with a color rendering index of 81 were fabricated by using a near-ultraviolet (NUV) chip, blue emitting single crystal TBC, green-emitting single crystal TPP2MnCl4 (C48H40P2MnCl4, abbreviated as TMC), and red-emitting single crystal TPP2SbCl5 (C48H40P2SbCl5, abbreviated as TSC). Moreover, the single-component white emission was achieved by doping Mn2+ and Sb3+ ions into the lattice of TBC. This work demonstrates the different emission mechanism of ns2 ions based OMHs, and the great potential of bismuth-based OMHs in the applications of WLEDs.

Synthesis and Luminescent Properties of Barium Molybdate Nanoparticles.

BaMoO4 was obtained via facile mechanochemical synthesis at room temperature and a solid-state reaction. An evaluation of the phase composition and structural and optical properties of BaMoO4 was conducted. The influence of different milling speeds on the preparation of BaMoO4 was explored. A shorter reaction time for the phase formation of BaMoO4 was achieved using a milling speed of 850 rpm. A milling speed of 500 rpm led to partial amorphization of the initial reagents and to prolongation of the synthesis time of up to 3 h of milling time. Solid-state synthesis was performed via heat treatment at 900 °C for 15 h. X-ray diffraction analysis (XRD), infrared (IR) and UV diffuse reflectance (UV-Vis) and photoluminescence (PL) spectroscopy were carried out to characterize the samples. Independently of the method of preparation, the obtained samples had tetragonal symmetry. The average crystallite sizes of all samples, calculated using Scherrer's formula, were in the range of 240 to 1540 Å. IR spectroscopy showed that more distorted structural MoO4 units were formed when the compound was synthesized via a solid-state reaction. The optical band gap energy of the obtained materials was found to decrease from 4.50 to 4.30 eV with increasing crystallite sizes. Green- and blue-light emissions were observed for BaMoO4 phases under excitation wavelengths of 330 and 488 nm. It was established that the intensity of the PL peaks depends on two factors: the symmetry of MoO4 units and the crystallite sizes.

High thermally stable deep red-emitting Sb3+,Ho3+-codoped Cs2NaScCl6 double perovskite for plant lighting

Lead-free halide double perovskite has received widespread attention due to its excellent optical performance. However, the lack of deep red light and poor heat quenching resistance severely limit its application in plant lighting field. In this work, Ho3+ was introduced into the thermally stable Cs2NaScCl6 host, exhibiting a deep red emission of 660 nm. By constructing an energy transfer channel between Sb3+ and Ho3+, the photoluminescence quantum yield (PLQY) of Cs2NaScCl6:1%Sb3+,40%Ho3+ rises up to 53.8%, that is increased by 17 times, and its emission intensity can still be maintained by 80% at 423 K, exhibiting good heat quenching resistance. The obtained Cs2NaScCl6:1%Sb3+,40%Ho3+ and Cs2NaScCl6:1%Sb3+ with blue light emission were employed for fabricating a light-emitting diode (LED) device with a 340 nm UV chip, and its emission spectrum matches well the absorption spectra of chlorophyll A and chlorophyll B with the high resemblance of 70% and 75%, making it suitable for use as an artificial light source to control the growth process of plants in the field of plant lighting.