The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Gary Rosengarten - One of the best experts on this subject based on the ideXlab platform.
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A spectrally splitting photovoltaic-thermal hybrid receiver utilising direct absorption and wave interference light Filtering
Solar Energy Materials and Solar Cells, 2015Co-Authors: Ahmad Mojiri, Cameron Stanley, Robert A. Taylor, Kourosh Kalantar-zadeh, Gary RosengartenAbstract:Abstract We have developed a novel spectrally splitting hybrid solar receiver by combining a simple Dichroic Filter and a liquid channel as a selective absorbing medium. The combination acts as a band pass Filter for silicon solar cells. The geometry can be optimised for any linear concentrator; in this paper we have optimised it for a commercially available linear rooftop micro-concentrator. The optics of the concentrator at its focal region has been investigated using ray tracing. A simple 5-layer Dichroic Filter made of titanium dioxide and silicon dioxide has been designed, optimised, and fabricated with a focus placed on manufacturing simplicity. It has been shown that such a Filter directs 54.5% of the concentrated light to the silicon photovoltaic cells; the Si cells considered in this paper can convert 26.1% of this energy into electricity which is significantly higher than their 20.6% efficiency under the full spectrum. This is due to the fact that 73.3% of the incident flux is within the cell's relatively high spectral response range, which can be efficiently converted into electricity. The rest of the spectrum can be collected as high temperature heat. This research shows the possibility of employing low-cost direct absorption-Dichroic Filtering hybrid receivers in liner concentrators.
Young Rag - One of the best experts on this subject based on the ideXlab platform.
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Realization of quantum dot-based polarized white LEDs using short-wavelength pass Dichroic Filters and reflective polarizer films
Thirteenth International Conference on Solid State Lighting, 2014Co-Authors: Su Ji Yang, Keyong Nam Lee, Young RagAbstract:This study introduces quantum dot (QD)-based polarized white light-emitting diodes (W-LEDs) combined with a shortwavelength pass Dichroic Filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions, and a reflective polarizer film (RPF)-sandwiched AgIn5S8-ZnS QD layer using an electrospray (e-spray) method. The AgIn5S8-ZnS QDs are good candidates for W-LEDs because of their broad emission band (~100 nm) from the donoracceptor emission. The yellow emitting AgIn5S8-ZnS QDs are synthesized using a colloidal hot injection method and mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for e-spray coating on glass. Furthermore, SPDFs are used instead of glass substrates to enhance the yellow emission from the QD layer. To create the polarized light, the RPF is fabricated on QD-coated glass and SPDFs. To create white light, a blue LED chip (λmax = 450 nm) is used as the blue light source and an excitation source for the yellow QD film with an applied current of 60 mA. The electroluminescence (EL) intensity with an angular orientation of the polarizer is measured as a function of the polarizer-rotating angle from −90° to 90° at 10° intervals.
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High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass Dichroic Filters
Thirteenth International Conference on Solid State Lighting, 2014Co-Authors: Hee Chang Yoon, Young RagAbstract:This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass Dichroic Filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.
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Polarized white light from LEDs using remote-phosphor layer sandwiched between reflective polarizer and light-recycling Dichroic Filter
Optics Express, 2013Co-Authors: Su Ji Yang, Young RagAbstract:This study introduces an efficient polarized, white phosphor-converted, light-emitting diode (pc-LED) using a remote phosphor film sandwiched between a reflective polarizer film (RPF) and a short-wavelength pass Dichroic Filter (SPDF). The on-axis brightness of polarized white light emission of a RPF/SPDF-sandwiched phosphor film over a blue LED, showed greater recovery than that of a conventional unpolarized remote phosphor film over blue LED, due to the recycling effect of yellow light from an SPDF. The relative luminous efficacy of an RPF/SPDF-sandwiched phosphor film was made 1.40 times better by adding an SPDF on the backside of an RPF-capped phosphor film. A polarization ratio of 0.84 was demonstrated for a white LED with an RPF/SPDF-sandwiched phosphor film, in good agreement with the measured results from the RPF-only sample.
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Improved color coordinates of green monochromatic pc-LED capped with a band-pass Filter
Optics express, 2013Co-Authors: Su Ji Yang, Yeon-goog Sung, Young RagAbstract:This study introduces a “greener” green monochromatic phosphor-converted light-emitting diode (pc-LED) using a band-pass Filter (BPF) combined with a long-pass Dichroic Filter (LPDF) and a short-pass Dichroic Filter (SPDF) to improve the color quality of our previously developed LPDF-capped green pc-LED. This can also address the drawbacks of III-V semiconductor-type green LEDs, which show a low luminous efficacy and a poor current dependence of the efficacy and color coordinates compared to blue semiconductor-type LEDs. The optical properties of green monochromatic pc-LEDs using a BPF are compared with those of LPDF-capped green pc-LEDs, which have a broad band spectrum, and III-V semiconductor-type green LEDs by changing the transmittance wavelength range of the BPF and the peak wavelength of the green phosphors. BPF-capped green monochromatic pc-LEDs provide a high luminous efficacy (134 lm/W at 60 mA), and “greener” 1931 Commission Internationale d'Eclairage (CIE; CIEx, CIEy) color coordinates (0.24, 0.66) owing to the narrowed emission spectrum. We also propose a two-dimensional (2D) polystyrene (PS) microbead (2-μm diameter) monolayer as a scattering layer to overcome the poor angular dependence of the color coordinates of the transmitted light through a nano-multilayered Dichroic Filter such as an LPDF or BPF. The 2D PS scattering layer improves the angular dependence of the green color emitted from a BPF-capped green pc-LED with only 3% loss of luminous efficacy.
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Highly-efficient, tunable green, phosphor-converted LEDs using a long-pass Dichroic Filter and a series of orthosilicate phosphors for tri-color white LEDs.
Optics Express, 2011Co-Authors: Hoo Keun Park, Yeon-goog Sung, Young RagAbstract:This study introduces a long-pass Dichroic Filter (LPDF) on top of a phosphor-converted LED (pc-LED) packing associated with each corresponding tunable orthosilicate ((Ba,Sr)2SiO4:Eu) phosphor in order to fabricate tunable green pc-LEDs. These LPDF-capped green pc-LEDs provide luminous efficacies between 143–173 lm/W at 60 mA in a wavelength range between 515 and 560 nm. These tunable green pc-LEDs can replace green semiconductor-type III-V LEDs, which present challenges with respect to generating high luminous efficacy. We also introduce the highly-efficient tunable green pc-LEDs into tri-color white LED systems that combine an InGaN blue LED and green/red full down-converted pc-LEDs. The effect of peak wavelength in the tunable green pc-LEDs on the optical properties of a tri-color package white LED is analyzed to determine the proper wavelength of green color for tri-color white LEDs. The tri-color white LED provides excellent luminous efficacy (81.5–109 lm/W) and a good color rendering index (64–87) at 6500 K of correlated color temperature (CCT) with the peak wavelength of green pc-LEDs. The luminous efficacy of the LPDF-capped green monochromatic pc-LED and tri-color package with tunable green pc-LEDs can be increased by improving the external quantum efficiency of blue LEDs and the conversion efficiency of green pc-LEDs.
Ahmad Mojiri - One of the best experts on this subject based on the ideXlab platform.
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A spectrally splitting photovoltaic-thermal hybrid receiver utilising direct absorption and wave interference light Filtering
Solar Energy Materials and Solar Cells, 2015Co-Authors: Ahmad Mojiri, Cameron Stanley, Robert A. Taylor, Kourosh Kalantar-zadeh, Gary RosengartenAbstract:Abstract We have developed a novel spectrally splitting hybrid solar receiver by combining a simple Dichroic Filter and a liquid channel as a selective absorbing medium. The combination acts as a band pass Filter for silicon solar cells. The geometry can be optimised for any linear concentrator; in this paper we have optimised it for a commercially available linear rooftop micro-concentrator. The optics of the concentrator at its focal region has been investigated using ray tracing. A simple 5-layer Dichroic Filter made of titanium dioxide and silicon dioxide has been designed, optimised, and fabricated with a focus placed on manufacturing simplicity. It has been shown that such a Filter directs 54.5% of the concentrated light to the silicon photovoltaic cells; the Si cells considered in this paper can convert 26.1% of this energy into electricity which is significantly higher than their 20.6% efficiency under the full spectrum. This is due to the fact that 73.3% of the incident flux is within the cell's relatively high spectral response range, which can be efficiently converted into electricity. The rest of the spectrum can be collected as high temperature heat. This research shows the possibility of employing low-cost direct absorption-Dichroic Filtering hybrid receivers in liner concentrators.
Cameron Stanley - One of the best experts on this subject based on the ideXlab platform.
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A spectrally splitting photovoltaic-thermal hybrid receiver utilising direct absorption and wave interference light Filtering
Solar Energy Materials and Solar Cells, 2015Co-Authors: Ahmad Mojiri, Cameron Stanley, Robert A. Taylor, Kourosh Kalantar-zadeh, Gary RosengartenAbstract:Abstract We have developed a novel spectrally splitting hybrid solar receiver by combining a simple Dichroic Filter and a liquid channel as a selective absorbing medium. The combination acts as a band pass Filter for silicon solar cells. The geometry can be optimised for any linear concentrator; in this paper we have optimised it for a commercially available linear rooftop micro-concentrator. The optics of the concentrator at its focal region has been investigated using ray tracing. A simple 5-layer Dichroic Filter made of titanium dioxide and silicon dioxide has been designed, optimised, and fabricated with a focus placed on manufacturing simplicity. It has been shown that such a Filter directs 54.5% of the concentrated light to the silicon photovoltaic cells; the Si cells considered in this paper can convert 26.1% of this energy into electricity which is significantly higher than their 20.6% efficiency under the full spectrum. This is due to the fact that 73.3% of the incident flux is within the cell's relatively high spectral response range, which can be efficiently converted into electricity. The rest of the spectrum can be collected as high temperature heat. This research shows the possibility of employing low-cost direct absorption-Dichroic Filtering hybrid receivers in liner concentrators.
Kourosh Kalantar-zadeh - One of the best experts on this subject based on the ideXlab platform.
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A spectrally splitting photovoltaic-thermal hybrid receiver utilising direct absorption and wave interference light Filtering
Solar Energy Materials and Solar Cells, 2015Co-Authors: Ahmad Mojiri, Cameron Stanley, Robert A. Taylor, Kourosh Kalantar-zadeh, Gary RosengartenAbstract:Abstract We have developed a novel spectrally splitting hybrid solar receiver by combining a simple Dichroic Filter and a liquid channel as a selective absorbing medium. The combination acts as a band pass Filter for silicon solar cells. The geometry can be optimised for any linear concentrator; in this paper we have optimised it for a commercially available linear rooftop micro-concentrator. The optics of the concentrator at its focal region has been investigated using ray tracing. A simple 5-layer Dichroic Filter made of titanium dioxide and silicon dioxide has been designed, optimised, and fabricated with a focus placed on manufacturing simplicity. It has been shown that such a Filter directs 54.5% of the concentrated light to the silicon photovoltaic cells; the Si cells considered in this paper can convert 26.1% of this energy into electricity which is significantly higher than their 20.6% efficiency under the full spectrum. This is due to the fact that 73.3% of the incident flux is within the cell's relatively high spectral response range, which can be efficiently converted into electricity. The rest of the spectrum can be collected as high temperature heat. This research shows the possibility of employing low-cost direct absorption-Dichroic Filtering hybrid receivers in liner concentrators.