Smart windows get darker to filter out the sun’s rays on bright days, and turn clear on cloudy days to let more light in. This feature can help control indoor temperatures and offers some privacy without resorting to aids such as mini-blinds.Now scientists report a new development in this growing niche: solar smart windows that can turn opaque on demand and even power other devices. The study appears in ACS Photonics (“Electrically Controllable Light Trapping for Self-Powered Switchable Solar Windows”).
Smart windows get darker to filter out the sun’s rays on bright days, and turn clear on cloudy days to let more light in. This feature can help control indoor temperatures and offers some privacy without resorting to mini-blinds. Now scientists report a new development in this growing niche: solar smart windows that can turn opaque on demand and even power other devices.
|Most existing solar-powered smart windows are designed to respond automatically to changing conditions, such as light or heat. But this means that on cool or cloudy days, consumers can’t flip a switch and tint the windows for privacy.|
|Also, these devices often operate on a mere fraction of the light energy they are exposed to while the rest gets absorbed by the windows. This heats them up, which can add warmth to a room that the windows are supposed to help keep cool. Jeremy Munday and colleagues wanted to address these limitations.|
|The researchers created a new smart window by sandwiching a polymer matrix containing microdroplets of liquid crystal materials, and an amorphous silicon layer — the type often used in solar cells — between two glass panes.
When the window is “off,” the liquid crystals scatter light, making the glass opaque. The silicon layer absorbs the light and provides the low power needed to align the crystals so light can pass through and make the window transparent when the window is turned “on” by the user.
|The extra energy that doesn’t go toward operating the window is harvested and could be redirected to power other devices, such as lights, TVs or smartphones, the researchers say.|
|Source: American Chemical Society|
|“By combining these two cells, the perovskite cell and the silicon cell, we are able to make much better use of the solar energy and achieve higher efficiencies than either cell on its own.”
Researchers at The Australian National University (ANU) have found a new way to fabricate high efficiency semi-transparent perovskite solar cells in a breakthrough that could lead to more efficient and cheaper solar electricity (Advanced Energy Materials, “Efficient Indium-Doped TiOxElectron Transport Layers for High-Performance Perovskite Solar Cells and Perovskite-Silicon Tandems”).
|Dr Tom White from the ANU Research School of Engineering said the new fabrication method significantly improved the performance of perovskite solar cells, which can combine with conventional silicon solar cells to produce more efficient solar electricity.|
|ANU Ph.D. student The Duong, Dr.Tom White and Ph.D. student Jun Peng.|
|He said perovskite solar cells were extremely good at making electricity from visible light – blue, green and red – while conventional silicon solar cells were more efficient at converting infrared light into electricity.|
|“The prospect of adding a few additional processing steps at the end of a silicon cell production line to make perovskite cells is very exciting and could boost solar efficiency from 25 per cent to 30 per cent,” Dr White said.|
|“By combining these two cells, the perovskite cell and the silicon cell, we are able to make much better use of the solar energy and achieve higher efficiencies than either cell on its own.”|
|While perovskite cells can improve efficiency, they are not yet stable enough to be used on rooftops. Dr White said the new fabrication technique could help develop more reliable perovskite cells.|
|The new fabrication method involves adding a small amount of the element indium into one of the cell layers during fabrication. That could increase the cell’s power output by as much as 25 per cent.|
|“We have been able to achieve a record efficiency of 16.6 per cent for a semi-transparent perovskite cell, and 24.5 per cent for a perovskite-silicon tandem, which is one of the highest efficiencies reported for this type of cell,” said Dr White.|
|Dr White said the research placed ANU in a small group of labs around the world with the capability to improve silicon solar cell efficiency using perovskites.|
|The development builds on the state-of-the-art silicon cell research at ANU and is part of a $12.2 million “High-efficiency silicon/perovskite solar cells” project led by University of New South Wales and supported by $3.6 million of funding from the Australian Renewable Energy Agency.|
|Research partners include Monash University, Arizona State University, Suntech R&D Australia Pty Ltd and Trina Solar.|
|Source: The Australian National University|
21 Nov 2016
Quantum computing is heralded as the next revolution in terms of global computing. Google, Intel and IBM are just some of the big names investing millions currently in the field of quantum computing which will enable faster, more efficient computing required to power the requirements of our future computing needs.
|Now a researcher and his team at Tyndall National Institute in Cork have made a ‘quantum leap’ by developing a technical step that could enable the use of quantum computers sooner than expected.|
|Conventional digital computing uses ‘on-off’ switches, but quantum computing looks to harness quantum state of matters – such as entangled photons of light or multiple states of atoms – to encode information. In theory, this can lead to much faster and more powerful computer processing, but the technology to underpin quantum computing is currently difficult to develop at scale.|
|Researchers at Tyndall have taken a step forward by making quantum dot light-emitting diodes (LEDs) that can produce entangled photons (whose actions are linked), theoretically enabling their use to encode information in quantum computing.|
|This is not the first time that LEDs have been made that can produce entangled photons, but the methods and materials described in the new paper (Nature Photonics, “Selective carrier injection into patterned arrays of pyramidal quantum dots for entangled photon light-emitting diodes”) have important implications for the future of quantum technologies, explains researcher Dr Emanuele Pelucchi, Head of Epitaxy and Physics of Nanostructures and a member of the Science Foundation Ireland-funded Irish Photonic Integration Centre (IPIC) at Tyndall National Institute in Cork.|
|Dr Emanuele Pelucchi.|
|“The new development here is that we have engineered a scalable array of electrically driven quantum dots using easily-sourced materials and conventional semiconductor fabrication technologies, and our method allows you to direct the position of these sources of entangled photons,” he says.|
|“Being able to control the positions of the quantum dots and to build them at scale are key factors to underpin more widespread use of quantum computing technologies as they develop.”|
|The Tyndall technology uses nanotechnology to electrify arrays of the pyramid-shaped quantum dots so they produce entangled photons. “We exploit intrinsic nanoscale properties of the whole “pyramidal” structure, in particular, an engineered self-assembled vertical quantum wire, which selectively injects current into the vicinity of a quantum dot,” explains Dr Pelucchi.|
|“The reported results are an important step towards the realization of integrated quantum photonic circuits designed for quantum information processing tasks, where thousands or more sources would function in unison.”|
|“It is exciting to see how research at Tyndall continues to break new ground, particularly in relation to this development in quantum computing. The significant breakthrough by Dr Pelucchi advances our understanding of how to harness the opportunity and power of quantum computing and undoubtedly accelerates progress in this field internationally. Photonics innovations by the IPIC team at Tyndall are being commercialized across a number sectors and as a result, we are directly driving global innovation through our investment, talent and research in this area,” said Dr Kieran Drain, CEO at Tyndall National Institute.|
|Source: Tyndall National Institute|