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A bipolar deep blue-emitting fluorescent material based on imidazole and triphenylamine for efficient non-doped OLEDs
摘要： A bipolar deep blue-emitting fluorescent material, 1-(4-tert-butyl phenyl)-2-[4-(N,N- diphenyl)phenyl]-4,5-diphenyl-1H-imidazole (TPA-PIM) has been designed and synthesized for efficient blue organic light-emitting diodes (OLEDs). The photophysical, thermal and electrochemical properties of TPA-PIM are investigated. TPA-PIM possesses high thermal stabilities with decomposition temperature of 396 °C and shows a strong deep-blue emission at 407 nm in N, N-dimethylformamide (DMF) solution. Single-carrier devices are fabricated to show that TPA-PIM has good bipolar characteristics. The non-doped fluorescent OLEDs using TPA-PIM as emitter exhibited stable and efficient deep-blue emissions with the CIE coordinates of (0.16, 0.09), the maximum luminance of 1392 cd m?2 and the maximum current efficiency of 2.60 cd A?1.
关键词： Triphenylamine,Blue light-emitting materials,Bipolar materials,Imidazole,Non-doped OLEDs
更新于2025-11-19 16:56:42
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Blue-light imaging has an additional value to white-light endoscopy in visualization of early Barrett's neoplasia: an international multicenter cohort study
摘要： Endoscopic features of early neoplasia in Barrett’s esophagus (BE) are subtle. Blue-light imaging (BLI) may improve visualization of neoplastic lesions. The aim of this study was to evaluate BLI in visualization of Barrett’s neoplasia. Methods: Corresponding white-light endoscopy (WLE) and BLI images of 40 BE lesions were obtained prospectively and assessed by 6 international experts in 3 assessments. Each assessment consisted of overview and magnification images. Assessments were as follows: assessment 1, WLE only; assessment 2, BLI only; and assessment 3, corresponding WLE and BLI images. Outcome parameters were as follows: (1) appreciation of macroscopic appearance and surface relief (visual analog scale scores); (2) ability to delineate lesions (visual analog scale scores); (3) preferred technique for delineation (ordinal scores); and (4) quantitative agreement on delineations (AND/OR scores). Results: Experts appreciated BLI significantly better than WLE for visualization of macroscopic appearance (median 8.0 vs 7.0, P < .001) and surface relief (8.0 vs 6.0, P < .001). For both overview and magnification images, experts appreciated BLI significantly better than WLE for ability to delineate lesions (8.0 vs 6.0, P < .001 and 8.0 vs 5.0, P < .001). There was no overall significant difference in AND/OR scores of WLE + BLI when compared with WLE, yet agreement increased significantly with WLE + BLI for cases with a low baseline AND/OR score on WLE, both in overview (mean difference, 0.15; P = .015) and magnification (mean difference, 0.10; P = .01). Conclusions: BLI has additional value for visualization of BE neoplasia. Experts appreciated BLI better than WLE for visualization and delineation of BE neoplasia. Quantitative agreement increased significantly when BLI was offered next to WLE for lesions that were hard to delineate with WLE alone.
关键词： neoplasia,white-light endoscopy,visualization,Barrett's esophagus,delineation,blue-light imaging
更新于2025-09-23 15:23:52
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Blue Electrogenerated Chemiluminescence from Halide Perovskite Nanocrystals
摘要： Electrogenerated chemiluminescence (ECL) has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources. Visible ECL emission can be obtained with a reasonable quantum yield and stability. Blue ECL is rare and often suffers from stability and poor quantum efficiency. Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals (PNCs), CH3NH3PbCl1.08Br1.92, is reported here for the first time using tripropylamine (TPrA) as co-reactant. The blue ECL emission peak resembles its photoluminescence peak position. In addition to this blue emission peak, the ECL spectra of CH3NH3PbCl1.08Br1.92 PNCs also showed a broad ECL peak at 745 nm. Generation of the second ECL peak at 745 nm from CH3NH3PbCl1.08Br1.92 PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation. Halide anion tunability of ECL emission from CH3NH3PbX3 (X: Cl, Br, I) PNCs is also demonstrated. The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation. The photoluminescence (PL) decay was described by PL lifetime (τ) of 1.2 ns. The effect of the addition of surfactants (oleic acid and n-octylamine) on the fluorescence intensity and stability of CH3NH3PbCl1.08Br1.92 PNCs is also discussed.
关键词： Surfactants,Blue light emission,ECL (electrogenerated chemiluminescence),Photoluminescence (PL),Perovskite nanocrystals (PNCs),Photoluminescence quantum yield (PLQY)
更新于2025-09-23 15:23:52
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Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking
摘要： Direct exposure to ultraviolet (UV) light is closely related to various harmful effects [1-3], ranging from skin injures to cancer originated from DNA damage. Recent years, some studies reported that blue light are also detrimental to humans [4,5], for example, the blue light could cause photochemical lesions to human retinal within the intensity range of the natural light [6]. Furthermore, blue light is responsible for the solar retinitis and may play a role in age-related macular degeneration. Importantly, the harmful effects of blue lights generated from the electronic display devices should also be careful [7]. Thus, the development of new UV and blue light shielding materials has been received much attention [8]. In the past few years, there has been an increased awareness of the importance to develop UV shielding materials. A variety of materials have been used to prevent UV lesions. Organic molecules like avobenzone or oxybenzone have been used as a UV absorber for many years, but the self-degradation limits their usage time. Inorganic materials such as zinc oxide (ZnO) and titanium oxide (TiO2) have been used intensively for UV shielding [9-12]. However, photocatalytic properties and self-degradations of the ZnO and TiO2 based absorbers also hindered their applications [13,14]. Other materials, e.g., graphene oxide-poly(vinyl alcohol) composite film and lanthanide complex functionalized cellulose nanopaper were also reported for UV shielding [15,16]. Whereas, the excellent UV-filtering capability of these films was obtained by sacrificing the visible light transmittance. Therefore, fabricating UV and blue light blocking materials with good photostability and high transparency to the rest of visible light still remains a challenge and is urgently needed to be developed. Recently, because of the outstanding performance in photovoltaic applications, lead halide perovskite APbX3 (where A = CH3NH3+, (NH2)2CH+ and Cs+, X = Cl?, Br? and I?) has become the most noticeable materials [17-22]. These perovskite nanocrystals exhibit intriguing features [23], such as easy tunable band gap, sharp optical absorption edges and high quantum efficiency with narrow emission spectra. These nanocrystals have been studied extensively for various optical applications, especially light emitting diodes and lasers [24-27]. Post modification of perovskite nanocrystals by anion exchange enables the absorbance band gap tuned from ultraviolet to near infrared spectra [28,29]. In addition, the perovskite nanocrystals show large absorption range, which offers the great potential for UV and blue light shielding applications. Although the tunable absorption-band edge of perovskite nanocrystals has already been realized, there have not been reports on developing UV and blue light blocking material with tunable absorption-band edge. Herein, we aim to the development of a simple and easy way to fabricate UV and blue light blocking material by mixing pervoskite nanocrystals and ethyl cellulose (EC). In this study, EC was used as a host material for the CsPb(Cl/Br)3 pervoskite nanocrystals. By tuning the ratio of Br to Cl, the blocked wavelength range could be easily controlled. Using the sharp absorption edges, the material possesses excellent light blocking ability in the range of 200-460 nm and maintains high transparency (95%) to visible light in the range beyond blue light.
关键词： UV blocking,Cesium lead halide nanocrystals,Blue light blocking,Tunable adsorption edge,Perovskite nanocrystals
更新于2025-09-23 15:23:52
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Research progress about the effect and prevention of blue light on eyes
摘要： ● In recent years, people have become increasingly attentive to light pollution influences on their eyes. In the visible spectrum, short-wave blue light with wavelength between 415 nm and 455 nm is closely related to eye light damage. This high energy blue light passes through the cornea and lens to the retina causing diseases such as dry eye, cataract, age-related macular degeneration, even stimulating the brain, inhibiting melatonin secretion, and enhancing adrenocortical hormone production, which will destroy the hormonal balance and directly affect sleep quality. Therefore, the effect of Blu-rays on ocular is becoming an important concern for the future. We describe blue light’s effects on eye tissues, summarize the research on eye injury and its physical prevention and medical treatment.
关键词： ocular injury,prevention,blue light
更新于2025-09-23 15:23:52
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Stomatal response to blue light in crassulacean acid metabolism plants <i>Kalanchoe pinnata</i> and <i>Kalanchoe daigremontiana</i>
摘要： Blue light (BL) is a fundamental cue for stomatal opening in both C3 and C4 plants. However, it is unknown whether crassulacean acid metabolism (CAM) plants open their stomata in response to BL. We investigated stomatal BL responses in the obligate CAM plants Kalanchoe pinnata and Kalanchoe daigremontiana that characteristically open their stomata at night and close them for part of the day, as contrasted with C3 and C4 plants. Stomata opened in response to weak BL superimposed on background red light in both intact leaves and detached epidermal peels of K. pinnata and K. daigremontiana. BL-dependent stomatal opening was completely inhibited by tautomycin and vanadate, which repress type 1 protein phosphatase and plasma membrane H+-ATPase, respectively. The plasma membrane H+-ATPase activator fusicoccin (FC) induced stomatal opening in the dark. Both BL and FC induced phosphorylation of the guard cell plasma membrane H+-ATPase in K. pinnata. These results indicate that BL-dependent stomatal opening occurs in the obligate CAM plants K. pinnata and K. daigremontiana independently of photosynthetic CO2 assimilation mode.
关键词： phototropins,CAM plants,plasma membrane H+-ATPase,stomatal opening,blue light,signal transduction
更新于2025-09-23 15:23:52
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Changes of Intracellular Porphyrin, Reactive Oxygen Species, and Fatty Acids Profiles During Inactivation of Methicillin-Resistant Staphylococcus aureus by Antimicrobial Blue Light
摘要： Antimicrobial blue light (aBL) has attracted increasing interest for its antimicrobial properties. However, the underlying bactericidal mechanism has not yet been verified. One hypothesis is that aBL causes the excitation of intracellular chromophores; leading to the generation of reactive oxygen species (ROS) and the resultant oxidization of various biomolecules. Thus, monitoring the levels of redox-sensitive intracellular biomolecules such as coproporphyrins, as well as singlet oxygen and various ROS may help to uncover the physiological changes induced by aBL and aid in establishing the underlying mechanism of action. Furthermore, the identification of novel targets of ROS, such as fatty acids, is of potential significance from a therapeutic perspective. In this study, we sought to investigate the molecular impact of aBL treatment on methicillin-resistant Staphylococcus aureus (MRSA). The results showed that aBL (5–80 J/cm2) exhibited a bactericidal effect on MRSA, and almost no bacteria survived when 80 J/cm2 had been delivered. Further studies revealed that the concentrations of certain intracellular molecules varied in response to aBL irradiation. Coproporphyrin levels were found to decrease gradually, while ROS levels increased rapidly. Moreover, imaging revealed the emergence and increase of singlet oxygen molecules. Concomitantly, the lipid peroxidation product malondialdehyde (MDA) increased in abundance and intracellular K+ leakage was observed, indicating permeability of the cell membrane. Atomic force microscopy showed that the cell surface exhibited a coarse appearance. Finally, fatty acid profiles at different illumination levels were monitored by GC-MS. The relative amounts of three unsaturated fatty acids (C16:1, C20:1, and C20:4) were decreased in response to aBL irradiation, which likely played a key role in the aforementioned membrane injuries. Collectively, these data suggest that the cell membrane is a major target of ROS during aBL irradiation, causing alterations to membrane lipid profiles, and in particular to the unsaturated fatty acid component.
关键词： membrane injuries,coproporphyrin,lipids,methicillin-resistant Staphylococcus aureus,antimicrobial blue light,unsaturated fatty acids
更新于2025-09-23 15:22:29
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Realizing efficient bipolar deep-blue light-emitting poly(2,7-carbazole) derivatives by suppressing intramolecular charge transfer
摘要： Two series of twisted bipolar poly(2,7-carbazole) derivatives, namely PCz-37RSOs and PCz-28SOs, were synthesized by introducing electron-deficient 2,8-dioctyl-dibenzothiophene-S,S-dioxide-3,7-diyl (37RSO) and dibenzothiophene-S,S-dioxide-2,8-diyl (28SO) unit into poly(9-heptadecanyl-2,7-carbazole) (PCz) backbone, respectively. The incorporation of electron-withdrawing 37RSO and 28SO into PCz backbone decreased effective conjugation length, and further restrained charge transfer effect existed in dipolar system, simultaneously, the balanced charge carrier injection/transportation were realized due to the electrophilicity of SO unit. Consequently, the resulting polymers showed hypsochromic shift and narrowed emission spectra regarding to PCz-37SOs that contains linear SO unit in main chain, and exhibited balanced hole/electron fluxes with respect to PCz in the range of 0–10 V. The single-layer devices based on resulting bipolar polymers exhibited excellent electroluminescent spectra stability in the current densities from 100 to 400 mA cm?2, and displayed deep blue electroluminescence spectra with the Commission Internationale de L’ Eclairage (CIE) of (0.16, 0.07) for PCz-37RSO5 and (0.16, 0.09) for PCz-28SO5. The superior device performance was achieved with the maximum luminous efficiency (LEmax) of 2.69 cd A?1 for PCz-28SO20, which obviously outperformed that of 0.24 cd A?1 for PCz. These results indicated that twisted molecular structure design is a promising strategy for efficient deep blue light-emitting polymers.
关键词： Poly(2,7-carbazole),Bipolar,Twisted structure,Blue light-emitting polymers,Charge transfer effect
更新于2025-09-23 15:22:29
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Physiological responses of pepper seedlings to various ratios of blue, green, and red light using LED lamps
摘要： Chlorophyll absorbs green light less e?ciently than it absorbs other wavelengths in the visible spectrum so green light drives photosynthesis less e?caciously. Green light emitting diodes (LEDs) are also less e?cacious at converting electrical energy into photons than their red and blue counterparts. Consequently, most photosynthetic LED lighting has been designed without including green wavelengths in the spectrum. Plant physiological research has largely focused on light signal responses to red, far-red and blue light, but recent e?orts suggest other wavebands may play an important role in plant development and photosynthetic activity. We have examined the role of monochromatic red, blue and green light and combinations of these colors with regard to seedling growth of bell pepper. The shoots of pepper plants grown under monochromatic green light had greater leaf area and lower speci?c leaf weight (mg cm?2) than those grown under monochromatic blue or red light. Green light also resulted in taller plants with greater dry weight and thicker stems relative to plants grown with blue light. A broad spectrum including red, green, and blue wavelengths resulted in the highest shoot dry weight and plant compactness.
关键词： Plant physiology,Green light,Blue light,Capsicum annuum,Red light,Light emitting diode
更新于2025-09-23 15:21:01
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Improved Color Purity of Monolithic Full Color Micro-LEDs Using Distributed Bragg Reflector and Blue Light Absorption Material
摘要： In this study, CdSe/ZnS core-shell quantum dots (QDs) with various dimensions were used as the color conversion materials. QDs with dimensions of 3 nm and 5 nm were excited by gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with a size of 30 μm × 30 μm to respectively form the green and red lights. The hybrid Bragg re?ector (HBR) with high re?ectivity at the regions of the blue, green, and red lights was fabricated on the bottom side of the micro-LEDs to re?ect the downward light. This could enhance the intensity of the green and red lights for the green and red QDs/micro-LEDs to 11% and 10%. The distributed Bragg re?ector (DBR) was fabricated on the QDs color conversion layers to re?ect the non-absorbed blue light that was not absorbed by the QDs, which could increase the probability of the QDs excited by the re?ected blue light. The blue light absorption material was deposited on the DBR to absorb the blue light that escaped from the DBR, which could enhance the color purity of the resulting green and red QDs/micro-LEDs to 90.9% and 90.3%, respectively.
关键词： micro-light-emitting diodes,color conversion layer,distributed Bragg re?ector,quantum dots,hybrid Bragg re?ector,blue light absorption material
更新于2025-09-23 15:21:01