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Wyświetlanie 1-10 z 16
Tytuł:
Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode
Autorzy:
Malik, S.
Usman, Muhammad
Hussain, M.
Munsif, M.
Khan, S.
Rasheed, S.
Ali, S.
Powiązania:
https://bibliotekanauki.pl/articles/1818198.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
ultraviolet
light-emitting diodes
efficiency
quantum wells
Opis:
The compositional graded quaternary barriers (GQBs) instead of ternary/conventional quantum barriers (QBs) have been used to numerically enhance the efficiency of AlGaN-based ultraviolet light-emitting diode (LED). The performance of LED with GQBs is examined through carrier concentrations, energy band diagrams, radiative recombination, electron and hole flux, internal quantum efficiency (IQE), and emission spectrum. As a function of the operating current density, a considerable reduction in efficiency droop is observed in the device with composition-graded quaternary barriers as compared to the conventional structure. The efficiency droop in case of a conventional LED is ~77% which decreased to ~33% in case of the proposed structure. Moreover, the concentration of electrons and holes across the active region in case of the proposed structure is increased to ~156% and ~44%, respectively
Źródło:
Opto-Electronics Review; 2021, 29, 3; 80--84
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure equation as novel strategy for optimum reflector design
Autorzy:
Ou, Chung-Jen
Powiązania:
https://bibliotekanauki.pl/articles/174423.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
illumination design
light-emitting diodes
structure equation
Opis:
The optimal use of energy resources is the central dogma for green technology and bio-optics. Reflectors provide a simple and fundamental structure for energy transport from a light emitting diode (LED) chip, and an appropriately designed reflector can reduce the fabrication cost of secondary optics for the LED. This paper demonstrates the role of three proposed reflector geometric factors in the two performance metrics – uniformity and collected energy (power), for designing LED reflectors. Through canonical factor analysis, a linear structure equation for LED reflector is suggested, and the methodology for designing the optimal shape is discussed. In addition, a generalized factor and a synthesis response are proposed for a more comprehensive investigation of optical performance. Results indicate a key parameter for balancing the optical performance, and the effects of various parameters and the trade-offs are revealed.
Źródło:
Optica Applicata; 2020, 50, 1; 95-110
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of the compositional graded quaternary barrier AlGaN-based ultraviolet-C light-emitting diode
Autorzy:
Malik, S.
Usman, Muhammad
Hussain, M.
Munsif, M.
Khan, S.
Rasheed, S.
Ali, S.
Powiązania:
https://bibliotekanauki.pl/articles/1818193.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
ultraviolet
light-emitting diodes
efficiency
quantum wells
Opis:
The compositional graded quaternary barriers (GQBs) instead of ternary/conventional quantum barriers (QBs) have been used to numerically enhance the efficiency of AlGaN-based ultraviolet light-emitting diode (LED). The performance of LED with GQBs is examined through carrier concentrations, energy band diagrams, radiative recombination, electron and hole flux, internal quantum efficiency (IQE), and emission spectrum. As a function of the operating current density, a considerable reduction in efficiency droop is observed in the device with composition-graded quaternary barriers as compared to the conventional structure. The efficiency droop in case of a conventional LED is ~77% which decreased to ~33% in case of the proposed structure. Moreover, the concentration of electrons and holes across the active region in case of the proposed structure is increased to ~156% and ~44%, respectively.
Źródło:
Opto-Electronics Review; 2021, 29, 3; 80--84
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Concept and implementation of adaptive road lighting concurrent with vehicles
Autorzy:
Zalewski, S.
Pracki, P.
Powiązania:
https://bibliotekanauki.pl/articles/200253.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
lighting technology
road lighting
lighting control
light emitting diodes
Opis:
The paper presents the authors’ concept of an adaptive road lighting that is concurrent with vehicles moving on roads. The lighting system is based on luminaires with light emitting diodes. The authors describe the operation of the adaptive road lighting system and point out benefits and limitations of the solution. The theoretical considerations are supported by an analysis of the installed and working system that was implemented at Bożeny street in Poznan, Poland. The system was also evaluated by the residents living near the street.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 6; 1117-1124
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of LED collimator for uniform illumination using two freeform lenses
Autorzy:
Zeng, J.
Li, X.
Ge, P.
Powiązania:
https://bibliotekanauki.pl/articles/173429.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
illumination design
lenses
light-emitting diodes
optical design
high uniformity
Opis:
Regulating the illuminance distribution of an LED collimator to produce a uniform illumination in both the near field and the far field is a challenge in illumination design. In this paper, we present an effective method for designing two separated freeform lenses to control the illuminance distribution and the direction of the rays from the LED. The first lens redistributes the ray energy, and the second one collimates them to obtain a uniform collimated illumination. According to the conservation law of energy, Snell’s law, Fermat’s law and tangent-plane iterative method, the two freeform surfaces could be calculated simultaneously. The simulation results show that the two freeform lenses can control most of rays into an angle within ±1.5° for an LED with 1 × 1 mm size. The illuminance uniformities are higher than 0.9 in both the near field and the far field.
Źródło:
Optica Applicata; 2018, 48, 3; 413-420
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected metrology problems implied by the application of LED technology in lighting
Wybrane problemy metrologiczne implikowane stosowaniem technologii LED w oświetleniu
Autorzy:
Błaszczak, U. J.
Zając, A. S.
Powiązania:
https://bibliotekanauki.pl/articles/408716.pdf
Data publikacji:
2016
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
light emitting diodes
measurement
lighting technology
diody elektroluminescencyjne
pomiary
technika świetlna
Opis:
High power LEDs replace traditional light sources in all possible lighting applications, causing significant problems in assessing the quality of lighting. This issue is not limited only to the construction aspects of the measuring equipment, but also has a cognitive dimension. The article presents an overview of the current state of knowledge on color rendering and evaluation of discomfort glare in relation to the widespread use of LEDs in lighting. Some selected parameters developed copyright sources with LED sets. Basic limitations in UGR measurement were indicated
Diody świecące dużej mocy zastępują klasyczne źródła światła właściwie we wszystkich możliwych aplikacjach oświetleniowych, co powoduje znaczne problemy w ocenie jakości oświetlenia. Zagadnienie to nie sprowadza się wyłącznie do aspektów konstrukcyjnych aparatury pomiarowej, lecz także ma wymiar poznawczy. W artykule przedstawiono przegląd aktualnego stanu wiedzy na temat oddawania barw oraz oceny olśnienia przykrego w odniesieniu do powszechnego stosowania diod LED w oświetleniu. Omówiono wybrane parametry opracowywanych autorskich źródeł z zestawami LED. Wskazano podstawowe ograniczenia w technice pomiarów UGR.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2016, 3; 6-11
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Light-Emitting Diodes Illumination Period and Light Intensity on High Rate Algal Reactor System in Laundry Wastewater Treatment
Autorzy:
Tangahu, B. V.
Triatmojo, A.
Purwanti, I. F.
Kurniawan, S. B.
Powiązania:
https://bibliotekanauki.pl/articles/123276.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
algae
Chlorella vulgaris
laundry wastewater
illumination period
light-emitting diodes
light intensity
microalgae
Opis:
Wastewater that contains high concentration of nutrients can create instability in water ecosystem if left untreated. Laundry wastewater contains nutrients in high concentration. The nutrients that commonly found in laundry wastewater are nitrogen and phosphorus. This study had a purpose to determine the effect of illumination period and light intensity for the removal of Chemical Oxygen Demand (COD), Nitrogen-ammonia (NH3-N), and phosphate (P) content using Chlorella vulgaris in High Rate Algal Reactor (HRAR) treatment. Variables that used were exposure period of 12 and 24 hours and light intensity of 2000–3000 Lux, 4000–5000 Lux, and 6000–7000 lux. The parameters tested to determine the efficiency of nutrient removal were COD, Nitrogen-ammonia, phosphate and Chlorophyll α to determine the condition of algae development. The results showed that the highest nutrient removal were obtained by the reactor with 24 hours illumination period with light intensity of 6000–7000 Lux that was capable of removing 54.63% of COD, and 22.15% of P. The 12-hour illumination period was better in terms of NH3-N removal, up to 50.07%. On the basis of the of statistic test result, the illumination period did not significantly influence the removal efficiency of COD, NH3-N and P indicated by P-value >0.05, while the light intensity significantly affect the removal of COD and NH3-N showed by P value <0.05.
Źródło:
Journal of Ecological Engineering; 2018, 19, 6; 170-175
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sprawność konwersji w luminoforach YAG:Ce współpracujących z emiterami półprzewodnikowymi z zakresu UV-VIS
Conversion efficency of the YAG:Ce luminophores cooperated with UV-VIS semicondutor emmiters
Autorzy:
Prorok, M. P.
Powiązania:
https://bibliotekanauki.pl/articles/408471.pdf
Data publikacji:
2017
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
luminofor
luminescencja
emiter półprzewodnikowy
temperatura barwowa
phosphors
luminescence
light emitting diodes
colour temperature
Opis:
Powszechnie stosowana metoda emisji światła białego wykorzystująca technologię LED-ową opiera się na użyciu luminoforu oraz emitera półprzewodnikowego z zakresu długości fali 440–460 nm (barwa niebieska). W wyniku zjawiska fotoluminescencji luminofor oparty na krysztale YAG-u z domieszkami ceru emituje szerokie spektrum z zakresu widzialnego o barwie zielonożółtej. Promieniowanie będące wynikiem fotoluminescencji, mieszając się ze źródłem wymuszającym daje barwę białą o temperaturze barwowej zależnej od typu luminoforu. W artykule przeprowadzone zostały badania dotyczące zarówno sprawności konwersji samego luminoforu jak i odpowiedzi spektralnej na niededykowane wymuszenie zrealizowane emiterami półprzewodnikowymi.
Commonly used white light emmision method utilizing LED technology depends mostly on luminophore and wavelenght 440–460 nm (blue) semicondutor emiter use. Emission of the wide visible spectrum, greenish yellow in colour, is an effect of fotoluminescence in cerium doped YAG cristal based luminophore. As the effect of fotoluminescence, radiation interferes with source radiation, resulting in white colour light with colour temperature depending on luminophore type. The article presents the research on both conversion efficency of the luminophore and the spectra response for the nondedicated forcing, realised by usage of semiconductor emitters.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2017, 7, 2; 74-77
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diody LED - odpady niebezpieczne dla środowiska
LED diodes - environmentally hazardous waste
Autorzy:
Sokołowska, W.
Karaś, A.
Zalewska, I.
Harasimowicz-Siemko, J.
Powiązania:
https://bibliotekanauki.pl/articles/192226.pdf
Data publikacji:
2011
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Materiałów Elektronicznych
Tematy:
dioda LED
ICP-OES
FAAS
ochrona środowiska
recykling
light-emitting diodes
environmental protection
recycling
Opis:
W Laboratorium Charakteryzacji Materiałów Wysokiej Czystości ITME przeprowadzono analizę składu chemicznego kilku rodzajów diod LED obecnych na polskim rynku [2]. Omówiono zawartość metali kancerogennych oraz metali niebezpiecznych dla środowiska . Porównano je z rezultatami uzyskanymi w UCI (Uniwersytet Kalifornia) opisanymi w [1] i normami TTCL.
An analysis of the chemical composition of several types of light-emitting diodes available on the Polish market was conducted in the Department of High Purity Materials Characterization of ITME [2]. In the course of the analysis, the content of carcinogenic metals and environmentally hazardous metals was explored. The findings were compared with the results achieved at the University of California, Irvine, described in [1], and with TTCL standards.
Źródło:
Materiały Elektroniczne; 2011, T. 39, nr 2, 2; 23-26
0209-0058
Pojawia się w:
Materiały Elektroniczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
C,N-cyklometalowane kompleksy irydu(III) : wydajne emitery fosforescencyjne dla organicznych diod elektroluminescencyjnych (OLED). Cz. 1 i 2
C,N-cyclometalated iridium(III) complexes : efficient phosphorescent emitters for organic electroluminescent diodes (OLED). Part 1 and 2
Autorzy:
Orwat, Bartosz
Kownacki, Ireneusz
Powiązania:
https://bibliotekanauki.pl/articles/1413294.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
emitery fosforescencyjne
diody elektroluminescencyjne
kompleksy irydu(III)
phosphorescent emitters
light-emitting diodes
iridium(III) complexes
Opis:
Organic electroluminescent panels have been widely available on the commercial market for several years, in the form of screens used in mobile phones, tablets, and TV sets. The display panels are produced in RGB technology, in which iridium(III) coordination compounds act as phosphorescent emitters of red and green light. Because of their high emission quantum efficiency and stability, the emitters containing 2-phenylpyridinato ligands and their derivatives have proved to be particularly useful. An interesting issue was the contrast between an extensive state of knowledge on the abovementioned compounds and a poor state of knowledge on analogous iridium(III) complexes equipped with benzo[h]quinolinato ligands. Application of the latter seemed interesting because of the similar size of benzo[h]quinoline and 2-phenylpyridine coordination pockets, but much more rigid structure and a greater degree of conjugation of the former, which could have a significant impact on the properties of complexes equipped with this type of ligand. Regarding to the above, this dissertation concerns the subject of the design and synthesis of new iridium(III) coordination compounds equipped with a benzo[h]quinoline motif, as well as the analysis of the structural changes impact on the photophysical, electroluminescent, thermal, electrochemical and spectroscopic properties of selected classes of compounds targeted for the application in OLED technology. Accordingly, the article presents the results of studies on two classes of heteroleptic of C,N-cyclometalated iridium(III) complexes, namely, of the salt type with the general formula [Ir(bzq)2(N^N)]+A-, stabilized by structurally different N,N-donating ligands, as well as neutral coordination compounds of the type [Ir(bzq)2(N^O)], bearing N,O-donating ß-ketoiminato ligands in the structure equipped with aryl moieties of various structure. The work included research on the determination of the correlation between the structure of ancillary ligand introduced into the coordination sphere of the metal and the above-mentioned properties. Additionally, based on the results of quantum-chemical calculations, work was undertaken to develop synthetic pathways enabling the incorporation to the C,N-cyclometalating benzo[h]quinoline ligand of substituents characterized by different stereo-electronic properties, enabling the modification of the emission parameters of the target complexes. In the next phase of research, the functionalized precursors of the bzq ligand were successfully used in the synthesis of binuclear complexes, key reagents in the preparation of corresponding mononuclear iridium coordination derivatives with electroluminescent properties.
Źródło:
Wiadomości Chemiczne; 2021, 75, 1-2; 163-231
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 16

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