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- light-emitting diode
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- Technical University of Gabrovo
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Narrow-Band Green-Emitting Sr <sub/>2</sub> MgAl <sub/>22</sub> O <sub/>36</sub> :Mn <sup>2+</sup> Phosphors with Superior Thermal Stability and Wide Color Gamut for Backlighting Display Applications
摘要： The narrow-band emitting phosphors have been extensively investigated in recent years, with the expectation that a wide color gamut of phosphor-converted backlighting device could be fabricated. Due to the weak electric–phonon interaction and low structural relaxation caused by the high rigid crystal structure and symmetric coordination environment, Sr2MgAl22O36:Mn2+ (SMAO:Mn2+) shows a narrow full-width at half-maximum of 26 nm, a high color purity of 81.5%, and a low thermal quenching (82% at 473 K of the initial intensity at 298 K). Using K2SiF6:Mn4+ as the red phosphor, SMAO:Mn2+ as the green one, and GaN-based chip as the blue component, the white light-emitting diode exhibits a National Television Standard Committee value of 127%. All the results demonstrate that the SMAO:Mn2+ phosphor has a promising application in the field of advanced wide-color-gamut backlight display, and the establishment of the relationships between the narrow-band emission and crystal structure can also be applied to design other novel narrow-band phosphors for backlighting technologies.
关键词： color gamut,inorganic phosphors,narrow-band emission,white light-emitting diodes,Sr2MgAl22O36:Mn2+,thermal stability,backlight displays
更新于2025-09-23 15:23:52
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New blue phosphorescence from trifluorosulfonyl-substituted iridium complexes
摘要： For color-pure phosphorescence organic light emitting diodes (PHOLEDs), we synthesized the trifluoromethyl sulfonyl substituted ligand and two new blue Iridium complexes with perfluoro-sulfonyl group (SOCF3pic and SOCF3mpic). The both iridium complexes showed similar photophysical and thermal properties while the HOMO energy leves of two Iridium complexes slightly differnet to be -5.84 eV for SOCF3pic and -5.74 eV for SOCF3mpic, respectively. The device with the SOCF3mpic dopant exhibited higher device efficiencies of 7.17 cd/A and 3.7 % compared to that with the SOCF3pic dopant (4.03 cd/A and 2.78 %). Two-dimensional GIXD images of scattered X-ray intensity from surface to full depth for SOCF3pic-doped and SOCF3mpic-doped TCTA:4PTPS films were characterized for preferential orientation along the out-of-plane direction.
关键词： preferential orientation along the out-of-plane direction,blue phosphorescence,iridium complex,grazing incidence wide-angle X-ray diffraction,organic light emitting diodes
更新于2025-09-23 15:23:52
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Ultrathin Fully Printed Light-Emitting Electrochemical Cells with Arbitrary Designs on Biocompatible Substrates
摘要： Organic electronic devices are often highlighted in terms of cost-efficient solution processing and potential printability. However, few studies are reporting truly full-solution-processed devices taking into account the electrodes as well as all other layers. This results in a production method that only partially benefits from the cost efficiency of solution processing and that still depends on costly and elaborate techniques like evaporation and/or lithography. This lack of knowledge is addressed by presenting a truly fully printed light-emitting electrochemical cell on ultraflexible parylene C substrates usable for conformable electronics. All device parts are fabricated by industrial relevant printing-techniques under ambient atmosphere. Inkjet printing is used for the structuring of the device layout and is therefore able to implement and create arbitrary designs. Further layers are produced by blade coating which is well suited for the coating of large areas. The devices show stable operation at a luminance higher than 100 cd m?2 for 8.8 h, can reach a maximum brightness of 918 cd m?2, and exhibit a turn-on time of 40 s to reach 100 cd m?2. Moreover, biocompatible and biodegradable materials are utilized to allow potential applications in life science and bioelectronics.
关键词： fully printed electronics,light-emitting electrochemical cells,parylene,inkjet,bioelectronics,digital printing,conformable electronics
更新于2025-09-23 15:23:52
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Hybrid ZnON-Organic Light Emitting Transistors with Low Threshold Voltage <5 V
摘要： The electrical and optical properties of inorganic–organic hybrid light emitting transistors (HLETs) are investigated, which are fabricated using the n-type semiconductor zinc-oxynitride (ZnON) as an electron transporting layer and the poly(p-phenylene vinylene)-based copolymer, Super Yellow (SY), as the light emitting layer. Additionally, the influence of various source (S)–drain (D) electrodes (Al, Ag, and Au) with different work functions (WFs) (4.1, 4.6, and 5.1 eV, respectively) on the performance of HLETs is studied. In order to increase the rate of hole injection from the metal electrodes and increase hole accumulation at the emissive layer, the use of a molybdenum oxide (MoOx) interlayer is also investigated. As a result, optimized devices using MoOx/Au hole injecting electrodes yield high brightness of up to 3.04 × 10^4 cd?m^?2 at a low threshold voltage of 4.79 V. This study provides valuable information about the role of the WF of S–D electrodes in HLETs, which may be exploited to improve the device performance of optoelectronic devices in the future.
关键词： zinc-oxynitride,light emitting transistors,work function,super yellow,low threshold voltage
更新于2025-09-23 15:23:52
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Simultaneous Singlet–Singlet and Triplet–Singlet F?rster Resonance Energy Transfer from a Single Donor Material
摘要： For almost 70 years, F?rster resonance energy transfer (FRET) has been investigated, implemented into nowadays experimental nanoscience techniques, and considered in a manifold of optics, photonics and optoelectronics applications. Here, we demonstrate for the first time simultaneous and efficient energy transfer from both donating singlet and triplet states of a single photoluminescent molecular species. Using a biluminescent donor that can emit with high yield from both excited states at room temperature allows to apply the FRET framework to such a bimodal system. It serves as an exclusive model system where the spatial origin of energy transfer is exactly the same for both donating spin states involved. Of paramount significance are the facts that both transfers can easily be observed by eye and that F?rster theory is successfully applied to state lifetimes spanning over eight orders of magnitude.
关键词： organic light-emitting diodes,energy transfer,biluminescence,dual state FRET
更新于2025-09-23 15:23:52
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Alternative Type 2D-3D Lead Halide Perovskite with Inorganic Sodium Ions as Spacer for High Performance Light Emitting Diodes
摘要： Two-dimensional (2D) lead halide perovskites with long-chain ammonium halides display high photoluminescence quantum yield (PLQY), due to their size and dielectric confinement, which promise a high efficiency and low-cost light emitting diode (LED). However, the presence of insulating organic long-chain spacer cation (L) dramatically deteriorates the charge transport properties along the out-of-plane nanoplatelet direction or adjacent nanocrystals, which would limit the LED device performance. In order to overcome this issue, we successfully incorporate small alkaline ions such as sodium (Na+) to replace long organic molecule. Grazing incident X-ray diffraction (GIXRD) measurements verify the 2D layered formation with preferential crystallite orientation. In addition, the incorporated sodium salt also generates amorphous sodium lead bromide (NaPbBr3) in perovskite as spacers to form nanocrystal-like halide perovskite film. PLQY is dramatically improved in the sodium incorporated film associating with enhanced PL lifetime. With incorporating small concentration of an organic additive, this 2D-3D perovskite can achieve a compact and uniform film. Therefore, a 2D-3D perovskite achieves a high external quantum efficiency (EQE) of 15.9% with good operational stability. Our work develops a type of 2D-3D halide perovskite with various inorganic ions as spacers for high performance of promising optoelectronic devices.
关键词： two-dimensional,alkaline halide,perovskite,dielectric confinement,light-emitting diode
更新于2025-09-23 15:23:52
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Therapeutic application of light emitting diode: Photo-oncomic approach
摘要： As a new light source, light emitting diode (LED) with high brightness and lower cost has been rapidly developed in medical application and light therapy. LED phototherapy can activate target cells with appropriate power and adequate energy density. This review provides general information on therapeutic applications of blue, green, yellow, red, and infrared LED in medical treatments for various physical abnormalities and on bio-imaging. The bio-imaging system is improved by decreasing the number of microscopes apparatuses including neutral-density filter, excitation filters and mechanical shutters. The numbers of excitation photons are increased and the fluorescent excitation efficiency is improved at cellular level. In the target tissue, the therapeutic effect of LEDs is dependent on incident photons irrespective of the system used to generate these photons. Photomodulated light from LED device is delivered in pulsed mode with specific pulse sequences and time. Too low or too high dose of energy may be ineffective at all. Clinical applications of LED light depending on different wavelengths are summarized. The author’s photo-oncomic experiments using a specific blue light emitting diode were introduced, showing that blue LED possessed anti-proliferative and anti-metastatic abilities in cancer cells and mice. As a promising light source, photo-oncomic approach of blue LED could be applied to treat cancers and inflammatory diseases.
关键词： cancer cell migration,photo-oncomic approach,Light emitting diode,growth
更新于2025-09-23 15:23:52
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Analysis of Thermal and Optical Characteristics of Light Emitting Diode on Various Heatsinks
摘要： Light emitting diodes (LED) are widely used in today’s world due to its less power consumption and its high luminance capacity. Around 20-30% of energy is converted to light energy and 70-80% of energy is dissipated as heat. The excessive rise in temperature causes failure to the LED. An effective thermal management is required for the proper heat dissipation in LED. In this work, the heat dissipation and the optical characteristics of the 16 W LED are studied using different types of aluminium heat sinks. The variation of case and junction temperature as well as the optical characteristic of LED is measured for different heatsink at different It was observed that heat sink with higher surface area shows the best result in terms of lower case and junction temperature. The higher luminous intensity was observed for the parallel fin type 1 heatsink due to higher surface area.
关键词： Heatsink,Case temperature,Light Emitting Diode (LED),Junction temperature
更新于2025-09-23 15:23:52
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[IEEE 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Varna (2018.9.20-2018.9.22)] 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Measurement and Determination of the Unified Glare Rating of Indoor Lighting Systems
摘要： The paper presents a results of software calculation and experimental measurement determination of unified glare rating (UGR) for two teacher rooms in an educational building. Three-dimensional computer modeling and multivariate UGR software calculation with light-emitting diode luminaires having different lighting distributions and taking into account the actual position and the line of sight of the observer are performed. A methodology for experimental measurement and determination of UGR has been proposed and demonstrated for the same two rooms. The results are presented in tabular and graphical form. A comparative analysis of the results obtained from the software calculations and the experimental determination of UGR is carried out. Conclusions have been made about the influence on the accuracy of the URG values obtained of the light distribution type of the luminaires, the location and orientation of the line of sight of the observer, and the choice of the background luminance surface.
关键词： indoor lighting,Unified Glare Rating,unified glare rating measurement,light-emitting diode luminaire
更新于2025-09-23 15:23:52
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High Speed Wireless Internet Using LiFi
摘要： The internet has become a basic necessity, so with the advancement in technology, people are demanding something faster than WI-FI. Since light is the only medium that can travel fastest than any other source of data transmission else so if we use this medium for internet, it will be the best utilization of medium with a higher data transmission rate. This technology was implemented over and came out with concept of LI-FI Technology. Li-Fi in known for Light-Fidelity, Li-Fi uses an idea of visible light communication (VLC) technology that uses light as a medium to convey fast high-speed communication in a manner like Wi-Fi. Since visible light is present everywhere, the main idea of our review paper is how LI-FI technology can help in security, speed and reliability of internet and even can change our life style. This innovation is actualized utilizing white LED bulbs matched with the Downlink transmitter that can give a higher information transmission rate up to 10Gbps. The main prospective of this paper demonstrates the forthcoming routine of Li-Fi technology innovation and its highlights to expand the execution of information transmission and different applications where Li-Fi has been put to utilize.
关键词： Data utilization,Visible Light communication,Wi-Fi,server,Light-emitting diode (LED),Light-Fidelity (Li-Fi),Video LAN Client (VLC)
更新于2025-09-23 15:22:29