scholarly journals A NOVEL SOLAR SIMULATOR BASED ON COMBINED NATURAL-WHITE AND INFRARED LIGHT EMITTING DIODES

2021 ◽  
Vol 56 (5) ◽  
pp. 583-594
Author(s):  
Napat Watjanatepin ◽  
Paiboon Kiatsookkanatorn
Keyword(s):  
Cooling System ◽  
Temporal Stability ◽  
Infrared Light ◽  
Reference Spectrum ◽  
White Led ◽  
Light Spectrum ◽  
Solar Simulator ◽  
Light Emitting ◽  
Custom Made ◽  
Positive Significant Correlation

Despite the continuous trend of an LED solar simulator development, there was little to be found in the application of a phosphor-converted natural white LED (pc-nWLED) for construction. This article reported the design and construction of an LED solar simulator which combined a pc-nWLED with infrared LEDs. The objectives of this study are to determine the performance of a novel solar simulator including non-uniformity (SNE), temporal stability (TIE), and spectrum mismatch (SM). This is followed by an experimental study of the correlation between the LED’s temperature and SNE. A spectroradiometer, pyranometer, and a custom-made non-uniformity measurement system were applied to test the performance characteristics of this solar simulator. The results indicated that the proposed solar simulator could achieve the AAA class. The results showed 0.90-1.08 of SM, 0.83% TIE, and 1.34% of SNE. The SNE indicated the positive significant correlation with the LED’s temperature, with an approximate of +0.043% per °C. A good cooling system for the LED module was necessary to maintain constant light uniformity. The blue-chip phosphor converted white LED combination with color mixed of 730 nm, 850 nm, and 940 nm could emit a light spectrum that was very close to the reference spectrum of about 99.6%.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

scholarly journals Antarctic krill (Euphausia superba) exhibit positive phototaxis to white LED light

Polar Biology ◽  
2021 ◽  
Vol 44 (3) ◽  
pp. 483-489
Author(s):  
Bjørn A. Krafft ◽  
Ludvig A. Krag
Keyword(s):  
Antarctic Krill ◽  
Light Exposure ◽  
Euphausia Superba ◽  
Marine Species ◽  
Artificial Light ◽  
White Led ◽  
Light Emitting ◽  
Positive Phototaxis ◽  
Led Light ◽  
Exposure Experiment

AbstractThe use of light-emitting diodes (LEDs) is increasingly used in fishing gears and its application is known to trigger negative or positive phototaxis (i.e., swimming away or toward the light source, respectively) for some marine species. However, our understanding of how artificial light influences behavior is poorly understood for many species and most studies can be characterized as trial and error experiments. In this study, we tested whether exposure to white LED light could initiate a phototactic response in Antarctic krill (Euphausia superba). Trawl-caught krill were used in a controlled artificial light exposure experiment conducted onboard a vessel in the Southern Ocean. The experiment was conducted in chambers with dark and light zones in which krill could move freely. Results showed that krill displayed a significant positive phototaxis. Understanding this behavioral response is relevant to development of krill fishing technology to improve scientific sampling gear, improve harvest efficiency, and reduce potential unwanted bycatch.

scholarly journals Increased Plant Quality, Greenhouse Productivity and Energy Efficiency with Broad-Spectrum LED Systems: A Case Study for Thyme (Thymus vulgaris L.)

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 960
Author(s):  
Jenny Manuela Tabbert ◽  
Hartwig Schulz ◽  
Andrea Krähmer
Keyword(s):  
Broad Spectrum ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Thymus Vulgaris ◽  
Light Spectrum ◽  
Light Emitting ◽  
Biomass Yields ◽  
Lighting Systems

A light-emitting diode (LED) system covering plant-receptive wavebands from ultraviolet to far-red radiation (360 to 760 nm, “white” light spectrum) was investigated for greenhouse productions of Thymus vulgaris L. Biomass yields and amounts of terpenoids were examined, and the lights’ productivity and electrical efficiency were determined. All results were compared to two conventionally used light fixture types (high-pressure sodium lamps (HPS) and fluorescent lights (FL)) under naturally low irradiation conditions during fall and winter in Berlin, Germany. Under LED, development of Thymus vulgaris L. was highly accelerated resulting in distinct fresh yield increases per square meter by 43% and 82.4% compared to HPS and FL, respectively. Dry yields per square meter also increased by 43.1% and 88.6% under LED compared to the HPS and FL lighting systems. While composition of terpenoids remained unaffected, their quantity per gram of leaf dry matter significantly increased under LED and HPS as compared to FL. Further, the power consumption calculations revealed energy savings of 31.3% and 20.1% for LED and FL, respectively, compared to HPS. In conclusion, the implementation of a broad-spectrum LED system has tremendous potential for increasing quantity and quality of Thymus vulgaris L. during naturally insufficient light conditions while significantly reducing energy consumption.

scholarly journals Two-dimensional perovskites with alternating cations in the interlayer space for stable light-emitting diodes

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yiyue Zhang ◽  
Masoumeh Keshavarz ◽  
Elke Debroye ◽  
Eduard Fron ◽  
Miriam Candelaria Rodríguez González ◽  
...  
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Interlayer Space ◽  
High Current Density ◽  
Operational Stability ◽  
Infrared Light ◽  
Two Dimensional ◽  
Commercial Development ◽  
Light Emitting

Abstract Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than their three-dimensional counterparts and rapidly catching up in performance. Herein, we demonstrate high-quality two-dimensional novel perovskite thin films with alternating cations in the interlayer space. This innovative perovskite provides highly stable semiconductor thin films for efficient near-infrared light-emitting diodes (LEDs). Highly efficient LEDs with tunable emission wavelengths from 680 to 770 nm along with excellent operational stability are demonstrated by varying the thickness of the interlayer spacer cation. Furthermore, the best-performing device exhibits an external quantum efficiency of 3.4% at a high current density (J) of 249 mA/cm2 and remains above 2.5% for a J up to 720 mA cm−2, leading to a high radiance of 77.5 W/Sr m2 when driven at 6 V. The same device also shows impressive operational stability, retaining almost 80% of its initial performance after operating at 20 mA/cm2 for 350 min. This work provides fundamental evidence that this novel alternating interlayer cation 2D perovskite can be a promising and stable photonic emitter.

scholarly journals Photoelectronic Properties of End-bonded InAsSb Nanowire Array Detector under Weak Light

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Xiaomei Yao ◽  
Xutao Zhang ◽  
Tingting Kang ◽  
Zhiyong Song ◽  
Qiang Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cooling System ◽  
Variable Temperature ◽  
Light Trapping ◽  
Nanowire Array ◽  
Infrared Light ◽  
Laser Source ◽  
Array Detector ◽  
Weak Light ◽  
Gap States

AbstractA simple fabrication of end-bonded contacts InAsSb NW (nanowire) array detector to weak light is demonstrated in this study. The detector is fabricated using InAsSb NW array grown by molecular beam epitaxy on GaAs substrate. The metal-induced gap states are induced by the end-bonded contact which suppresses the dark current at various temperatures. The existence of the interface dipole due to the interfacial gap states enhances the light excitation around the local field and thus upgrades the photoresponsivity and photodetectivity to the weak light. The light intensity of the infrared light source in this report is 14 nW/cm2 which is about 3 to 4 orders of magnitude less than the laser source. The responsivity of the detector has reached 28.57 A/W at room temperature with the light (945 nm) radiation, while the detectivity is 4.81 × 1011 cm·Hz1/2 W−1. Anomalous temperature-dependent performance emerges at the variable temperature experiments, and we discussed the detailed mechanism behind the nonlinear relationship between the photoresponse of the device and temperatures. Besides, the optoelectronic characteristics of the detector clarified that the light-trapping effect and photogating effect of the NWs can enhance the photoresponse to the weak light across ultraviolet to near-infrared. These results highlight the feasibility of the InAsSb NW array detector to the infrared weak light without a cooling system.

scholarly journals Study of the Effect of TiO2 Layer on the Adsorption and Photocatalytic Activity of TiO2-MoS2 Heterostructures under Visible-Infrared Light

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
N. Cruz-González ◽  
O. Calzadilla ◽  
J. Roque ◽  
F. Chalé-Lara ◽  
J. K. Olarte ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Nitrogen Adsorption ◽  
High Photocatalytic Activity ◽  
Infrared Light ◽  
Polluted Water ◽  
Light Spectrum ◽  
X Ray

In the last decade, the urgent need to environmental protection has promoted the development of new materials with potential applications to remediate air and polluted water. In this work, the effect of the TiO2 thin layer over MoS2 material in photocatalytic activity is reported. We prepared different heterostructures, using a combination of electrospinning, solvothermal, and spin-coating techniques. The properties of the samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), and X-ray photoelectron spectroscopy (XPS). The adsorption and photocatalytic activity were evaluated by discoloration of rhodamine B solution. The TiO2-MoS2/TiO2 heterostructure presented three optical absorption edges at 1.3 eV, 2.28 eV, and 3.23 eV. The high adsorption capacity of MoS2 was eliminated with the addition of TiO2 thin film. The samples show high photocatalytic activity in the visible-IR light spectrum.

Metalorganic Molecular Beam Epitaxy of GaAsP for Visible Light-Emitting Devices on Si

1998 ◽  
Vol 535 ◽  
Author(s):  
M. Yoshimoto ◽  
J. Saraie ◽  
T. Yasui ◽  
S. HA ◽  
H. Matsunami
Keyword(s):  
Molecular Beam Epitaxy ◽  
Visible Light ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Infrared Light ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Good Crystallinity ◽  
Metalorganic Molecular Beam Epitaxy ◽  
Pre Treatment

AbstractGaAs1–xPx (0.2 <; x < 0.7) was grown by metalorganic molecular beam epitaxy with a GaP buffer layer on Si for visible light-emitting devices. Insertion of the GaP buffer layer resulted in bright photoluminescence of the GaAsP epilayer. Pre-treatment of the Si substrate to avoid SiC formation was also critical to obtain good crystallinity of GaAsP. Dislocation formation, microstructure and photoluminescence in GaAsP grown layer are described. A GaAsP pn junction fabricated on GaP emitted visible light (˜1.86 eV). An initial GaAsP pn diode fabricated on Si emitted infrared light.

Heat-resistant reflectors for enhanced 850-nm near infrared light-emitting diode efficiency

2021 ◽  
pp. 103879
Author(s):  
Hyung-Joo Lee ◽  
Gwang-Hoon Park ◽  
Jin-Su So ◽  
Choong-Hun Lee ◽  
Jae-Hoon Kim ◽  
...  
Keyword(s):  
Near Infrared ◽  
Light Emitting Diode ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Light Emitting ◽  
Heat Resistant

scholarly journals Amelioration of oral mucositis pain by NASA near-infrared light-emitting diodes in bone marrow transplant patients

2011 ◽  
Vol 20 (7) ◽  
pp. 1405-1415 ◽  
Author(s):  
Brian D. Hodgson ◽  
David M. Margolis ◽  
Donna E. Salzman ◽  
Dan Eastwood ◽  
Sergey Tarima ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplant ◽  
Oral Mucositis ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Marrow Transplant ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Light Emitting ◽  
Transplant Patients

Evaluation of Static Performance of Optoelectronic Semiconductor Devices under X-Rays Irradiation

2010 ◽  
Vol 173 ◽  
pp. 1-6 ◽  
Author(s):  
Haider F. Abdul Amir ◽  
Fuei Pien Chee
Keyword(s):  
Ionizing Radiation ◽  
Light Emitting Diode ◽  
Optoelectronic Devices ◽  
Third Party ◽  
Infrared Light ◽  
X Rays ◽  
Total Ionizing Dose ◽  
Light Emitting ◽  
Static Performance ◽  
Current Drives

In this research, optoelectronic devices consisted of an infrared light emitting diode and a phototransistor with no special handling or third party-packaging were irradiated to ionizing radiation utilizing x-rays. It was found that the devices under test (DUTs) undergo performance degradation in their functional parameters during exposure to x-rays. These damaging effects are depending on their current drives and also the Total Ionizing Dose (TID) absorbed. The TID effects by x-rays are cumulative and gradually take place throughout the lifecycle of the devices exposed to radiation.

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