Chinese scientists unveil energy-generating window


072613solarScientists in China said on Thursday they had designed a “smart” window that can both save and generate energy, and may ultimately reduce heating and cooling costs for buildings.

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Scientists in China have designed a window that can save and generate energy. Photo: Reuters

While allowing us to feel close to the outside world, windows cause heat to escape from buildings in winter and let the sun’s unwanted rays enter in summer.

This has sparked a quest for “smart” windows that can adapt to weather conditions outside.

Today’s smart windows are limited to regulating light and heat from the sun, allowing a lot of potential energy to escape, study co-author Yanfeng Gao of the Chinese Academy of Sciences said.

“The main innovation of this work is that it developed a concept smart window device for simultaneous generation and saving of energy.”

Engineers have long battled to incorporate energy-generating solar cells into window panes without affecting their transparency.

Gao’s team discovered that a material called vanadium oxide (VO2) can be used as a transparent coating to regulate infrared radiation from the sun.

VO2 changes its properties based on temperature. Below a certain level it is insulating and lets through infrared light, while at another temperature it becomes reflective.

A window in which VO2 was used could regulate the amount of sun energy entering a building, but also scatter light to solar cells the team had placed around their glass panels, where it was used to generate energy with which to light a lamp, for example.

“This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner,” the study authors wrote in the journal Nature Scientific Reports.

Advances in R2R barrier technologies to Help Plastic Electronics Continuous Production


201306047919620A number of promising barrier technologies that could be used in the industrial production of plastic electronics are being developed for continuous production processes.

Roth & Rau's PECVD tool is used by the Holst Centre for barrier/encapsulation technology developmentFlexible barrier and encapsulation technologies improve the shelf life of devices such as flexible OLED lighting and OPVs from moisture ingress particularly, which tend to cause the technology to degrade.

Requirements for plastic electronics are higher than other technologies as some devices will need a shelf life of several years, while the level of protection can also depend heavily on the application – barrier and encapsulation requirements for a flexible OPV device, used to power an indoor sensor system, will be different to a flexible OLED lighting product, which will differ to an outdoor building- integrated PV (BIPV) application for an OPV panel. In addition high barrier technologies for plastic electronics have to be manufactured cost-effectively.

Plastic electronics R&D clusters in Europe are beginning to make headway in this area. In 2010 plasma-enhanced chemical vapour deposition (PECVD) technology equipment supplier Roth & Rau Microsystems joined the Holst Centre‘s large area flexible electronics programme, specifically to work on roll-to-roll (R2R) deposition tools for transparent high barrier layers.

Progress

OLED lighting devices using the batch-processed thin film flexible barrier technology have been validated in accelerated lifetime tests, while Roth & Rau Microsystems continue to scale the process for R2R.

The Holst Centre’s PECVD barrier technology is also being used in the Solliance project, of which Holst Centre is a founding R&D partner, as a baseline process, for flexible solution processable OPVs, though other barrier technologies and processes that have the potential to be more cost-effective are also being investigated.

In the UK, the Centre for Process Innovation (CPI) is working closely with atomic layer deposition (ALD) tool supplier Beneq. The partners will, together, develop an industry-ready transparent high-barrier/encapsulation process that can be applied using an R2R ALD tool that the CPI has bought from Beneq.

In future, might this mean that the CPI and Beneq are able to collaboratively offer barrier technologies to the plastic electronics industry – Beneq the production tool and CPI the know-how – which may differ depending on devices and applications for devices. Potentially barriers can be applied in several ways, including supplied as a standalone transparent film product that can be laminated onto a device, applied directly onto a device, or applied as a layer on to a film/foil substrate that devices are made on. Investigation and development of these will be done by the CPI.