![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
. | ![]() |
. |
![]() by Staff Writers Johannesburg, South Africa (SPX) Nov 12, 2021
Light bulbs are a big upgrade from fires and candles. Every year homes in informal settlements burn down in Africa because of fires used for heating and lighting. So electrical light bulbs with filaments brought about a revolution at home and work. Still, all these options are too hot to handle carelessly. They also give off lots of heat, and light up everything around them with a rosy-tinged hue. In other words, good for romance and atmosphere but not good for low lighting bills. Then fluorescent lighting came along, using much less energy. These are fragile, prone to flickering, and contain poisonous mercury vapours.
Risking fire at home An LED bulb can be a cozy "warm white" light or a "cold white" for offices. LED bulbs don't get hot and don't break easily. Their light can be focused, so it is easy to light up only what is needed. Current LED bulbs are ideal for those with the finances to keep replacing them, and to pay ever-rising electricity bills. LEDs also function well in battery-powered lanterns during powerouts or camping trips. This still leaves a huge number of households and businesses across the globe vulnerable to inadequate lighting. Or risking a fire at home because someone burns candles to see what they are cooking, or to study. But if a LED bulb can be a fraction of the cost and last much longer, safe lighting can become accessible to more people.
Double the intensity "The material has to be chemically stable to make a long-lasting device. It should not degrade much over time. It should last as least twice as long as current materials, and be highly energy efficient. It needs to surpass what's available in the market today," he adds. In an article published in Luminescence, Ntwaeaborwa and others show how adding a common compound to a safe light-emitting material can create much brighter light. They added sulphate, to zinc oxide doped with the rare earth cerium, to get the improvement. They shone a laser on the compound to get it to emit light in the laboratory-based research. "When we add sulphate to cerium-doped zinc oxide, the intensity of the emitted light is doubled. If this material is used in electronic devices in future, those will last much longer as well," says Ntwaeaborwa.
Physics of better light "The intensity of light emitted by zinc oxide doped with cerium is low. Adding the sulphate increases the intensity. In other words, the material emits a brighter light with the same laser excitation," he adds. "The sulphate helps the compound to better absorb the primary excitation from the laser, and to transfer this excitation to the light centres in the compound."
Colour edge in the search "Compared to commercial LED bulbs, the light emitting material in this research is still a long way from reaching the same light intensity and durability. The intensity with the added sulphate is roughly half that of commercially used materials. "However, the material is a promising candidate for future use in commercial LED lighting applications," he says.
Red green blue grand slam "The material can emit different colours of light, depending on the excitation used to get the light emission," says Dr Balakrishna Avula, a co-author from UJ. With one energy source, the material can be 'excited' into emitting red or blue or green light. This property is called chromaticity. And it is the single most important property in the search for cheap LED lighting, he says. "When we add sulphate, the intensity of the red, blue and green light we get from the material, using the same laser for excitation, doubles," he adds.
Three in one to slash costs In the study, adding the sulphate to cerium-doped zinc oxide also resulted in double the intensity of white light emitted. "LED bulbs are expensive because we need three LEDs in one bulb to get white light. We need a red, a green and a blue. The three shining at the same time results in white light. This means a more complex bulb design which uses more materials," says Ntwaeaborwa. "If only one LED making white light can be used, that will be more cost-effective to manufacture, and LED bulbs can be much cheaper," he adds.
No fires in the lab "If you don't yet know the basic properties of a compound, and how it will react to a laser or electricity, it can heat up and even explode. So, you must take precautions when exploring new materials. Once the basic science is understood, it becomes feasible to move research into a technology phase, he adds." Both zinc oxide and sulphate don't melt, or catch fire, explode, or degrade much over time. They also don't break easily. Both are easy to prepare in the lab, safe, non-toxic, and economical to work with. They're environmentally friendly, and unlikely to create problems in storage, during manufacture, or in landfills. The next step is to measure the brightness of the emitted light directly, and to improve the brightness beyond that of materials currently used in LED bulbs. "When using a single LED in a bulb for white light, the LED will have to be at least twice as bright as the ones used now. Fortunately, physics tells us that a brighter material will also last much longer," says Ntwaeaborwa.
Research Report: "The role of sulfate ions on distinctive defect emissions in ZnO:Ce3+ nanophosphors - A study on the application in color display systems"
![]() ![]() Chip maker TSMC, Sony partner on new $7 bn plant in Japan Tokyo (AFP) Nov 9, 2021 Taiwanese chip giant TSMC will partner with Sony on a new $7 billion plant in Japan, the firms announced Tuesday, as an ongoing global semiconductor shortage squeezes the production of everything from cars to TVs and gaming consoles. Taiwan Semiconductor Manufacturing Company (TSMC) had announced plans for its first plant in Japan earlier this month, with construction expected to begin next year. But it offered more details in a statement on Tuesday, including that the initial expenditure on the ... read more
![]() |
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |