摘要 :
Abstract A method for measuring the central wavelength and bandwidth of a light emitting diode (LED) using the Michelson interferometer is proposed. It is easy to see the interference fringes on the screen by setting the optical p...
展开
Abstract A method for measuring the central wavelength and bandwidth of a light emitting diode (LED) using the Michelson interferometer is proposed. It is easy to see the interference fringes on the screen by setting the optical path properly. Based on it, the central wavelength and bandwidth of LEDs with three different colours are measured, and the experimental results are consistent with the results from a spectrometer. The experiment will be helpful for students to understand the spectral and coherence characteristics of LEDs. It can also be an extended content of Michelson interferometer.
收起
摘要 :
Engineering the position of the lowest triplet state (T~1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. We h...
展开
Engineering the position of the lowest triplet state (T~1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. We have carried out model exact calculations of substituted polyene chains to understand the factors that affect the energy gap between S~1 and T~1. The factors studied are backbone dimerisation, different donor-acceptor substitutions, and twisted geometry. The largest system studied is an 18 carbon polyene which spans a Hilbert space of about 991 × 10~6. We show that for reverse intersystem crossing process, the best system involves substituting all carbon sites on one half of the polyene with donors and the other half with acceptors
收起
摘要 :
This paper reports a new type of soft PDMS/metal-film photo-mask that can be applied in contact photolithography with a resolution at sub-micrometer scale and a patterning area over a 4-in wafer. This new type of photo-mask is mad...
展开
This paper reports a new type of soft PDMS/metal-film photo-mask that can be applied in contact photolithography with a resolution at sub-micrometer scale and a patterning area over a 4-in wafer. This new type of photo-mask is made from a soft PDMS mold that contains a patterned metal film on the concave surface of its microstructures. The metal film can selectively block incident UV light, while the convex PDMS microstructures can guide the incident UV light to expose a photo-resist (PR) layer. Due to its soft and compliant property, this new soft photo-mask can form intimate contact with a substrate and carry out UV exposure to form PR microstructures. It is particularly useful in patterning slightly curved substrates such as sapphire wafers, and therefore has a great potential on manufacturing patterned sapphire substrates (PSSs) in light-emitting diodes. In this paper, both 2 and 4 in PSSs with sub-micrometer feature sizes are successfully achieved. This new type of soft photo-mask and its contact photolithography can be easily implemented at a low cost for large-area, nonflat, and sub-micrometer scaled patterning, and therefore has great potential in many applications. $hfill[2013{hbox{-}}0030]$
收起
摘要 :
Synthesis of new PVK and 1H-pyrazolo[3,4-b]quinoline based copolymers for electro-optic applications is described. Both copolymers are soluble and can be processed into thin films. A single layer OLED structure was fabricated and ...
展开
Synthesis of new PVK and 1H-pyrazolo[3,4-b]quinoline based copolymers for electro-optic applications is described. Both copolymers are soluble and can be processed into thin films. A single layer OLED structure was fabricated and a blue light emission was observed. Although devices were not optimized, the "turn-on bias voltage was relatively low, ca. 12 V.
收起
摘要 :
The paper presents possibilities of illumination of work areas with white Light Emitting Diodes (LED). The work task area is illuminated with a local lighting fitting and with a general lighting system (producing illumination 300 ...
展开
The paper presents possibilities of illumination of work areas with white Light Emitting Diodes (LED). The work task area is illuminated with a local lighting fitting and with a general lighting system (producing illumination 300 Ix) as well. Geometry of the lighting system has been discussed: illuminated work area, visual task area and position of the lighting fitting. Computer simulation of lighting systems based on different types of LEDs and analyses of results of lighting of a reference work area have been carried out. Technical parameters such as average illumination on the visual task area and its neighbourhood, illumination uniformity and coefficient of utilisation have been determined.
收起
摘要 :
The electrical lighting industry is in the midst of the biggest and most rapid change in its history. Conventional light sources that have been used for decades are being pushed aside in favor of solid-state lighting (SSL). LEDs, ...
展开
The electrical lighting industry is in the midst of the biggest and most rapid change in its history. Conventional light sources that have been used for decades are being pushed aside in favor of solid-state lighting (SSL). LEDs, along with lesser known sources, offer longer life and significant energy savings over their predecessors. Although most of the breaking news deals with LEDs, other sources, such as organic LEDs and plasma, are changing the face of the lighting industry as we know it. In addition, several existing light sources are reinventing themselves in an attempt to meet the economic performance of LEDs. SSL light sources are also changing the language of lighting and how we measure the light source and fixture performance. Everything we knew about lighting is changing and will continue to change for the next few years. This paper discusses what is changing, various light sources, and the impact it is having and will have on the application of lighting.
收起
摘要 :
The recent development of polymer light emitting diodes (PLEDs) has triggered a lot of interest for their use in displays, backlights, and for lighting applications. Their high efficiency and ease of manufacturing make PLEDs espec...
展开
The recent development of polymer light emitting diodes (PLEDs) has triggered a lot of interest for their use in displays, backlights, and for lighting applications. Their high efficiency and ease of manufacturing make PLEDs especially attractive. Various conjugated polymers have been employed, but especially soluble phenyl-poly-p-phenylene vinylene(s) show excellent properties.The chemical as well as the structural purity of the polymers has proven to be essential for high performance, long lifetime PLEDs. Mechanistic investigations allowed the identification of one major polymerization defect in PPVs, the so called tolane-bisbenzyl moiety. This in turn has enabled us to eliminate the most significant failure mechanism of these PPVs during device operation.The newly developed polymers are manufactured on an industrial scale. A combination of a glass lined 370/560L vessel cascade allows manufacturing in kilogram scale quantities while still maintaining high purity levels. A significant extension of this facility is now in use and ensures availability of large quantities ready-to-use solution of various light emitting polymers with photo-resist type purity.
收起
摘要 :
The design of white light-emitting diodes is carried out to achieve highly efficient white light emission with superior color quality, good vision performance, and healthy effect on human circadian rhythms. Here, the white light i...
展开
The design of white light-emitting diodes is carried out to achieve highly efficient white light emission with superior color quality, good vision performance, and healthy effect on human circadian rhythms. Here, the white light is obtained by combing five different emissions (blue, cyan, green, yellow, and red) from organolead halide perovskites [MAPb(BrxI1-x)3, MA-CH3NH3]. The color characteristics are evaluated by calculating the CIE coordinates, the correlated-color temperature (CCT), the color-rendering indices (CRI: Ra, R9-R15), and the Duv. Vision performance is evaluated by calculating the luminous efficacy of radiation. The effect of white light on human circadian rhythms is evaluated by calculating the circadian action factor (CAF). The results show that the white lights with a tunable CCT from 2851?K to 8315?K, extremely high CRI (up to 98.7), and small Duv (0.0002 – 0.0055) have been obtained by engineering the spectral power distributions. In addition, excellent vision performance and highly tunable CAF are demonstrated. These findings demonstrate that these types of materials are promising candidates to achieve highly efficient white light emission with excellent color quality and vision performance.
收起
摘要 :
We have used for the first time the laser intensity modulation method (LIMM) to resolve the depth profile of space charges in films of poly[(2-(2-ethylhexyl)-5-methoxy-1,4-phenylene)vinylene] (MEH-PPV), poly(pyridine-2,5-diyl) (PP...
展开
We have used for the first time the laser intensity modulation method (LIMM) to resolve the depth profile of space charges in films of poly[(2-(2-ethylhexyl)-5-methoxy-1,4-phenylene)vinylene] (MEH-PPV), poly(pyridine-2,5-diyl) (PPY) and poly(fluorene) (PFO). The results demonstrate that in conjugated polymers space charges can not only be created but also stored permanently.
收起
摘要 :
The optimal spectral parameters and photometric performances of white LEDs with red LEDs instead of phosphor (pc/R-WLEDs) for the color fidelity index (Rf) above 97 at correlated color temperatures (CCTs) of 2700?K to 6500?K have ...
展开
The optimal spectral parameters and photometric performances of white LEDs with red LEDs instead of phosphor (pc/R-WLEDs) for the color fidelity index (Rf) above 97 at correlated color temperatures (CCTs) of 2700?K to 6500?K have been obtained based on the luminous efficacy (LE) model. We have first reported four real pc/R-WLEDs with Rfs of 96–97 and LEs of 120–124 lm/W at CCTs of 2969?K, 4468?K, 5682?K, and 6558?K by using blue (448?nm) and red (650?nm) LEDs, as well as green (507?nm) and yellow (586?nm) phosphors. As compared with phosphor-converted white LEDs (pc-WLEDs) as well as quantum dots white LEDs (QD-WLED), it was found that the pc/R-WLEDs, not the QD-WLED as widely expected, make strong candidates for excellent color rendition, especially in the low color temperature range, for replacing current pc-WLEDs in the future.
收起
原文获取