29 June 2012

The OLED TVs About to Enter the Market

I remember in the early 2000s when attending to a conference I came across for the first time the Organic Light Emitting Diodes (OLED) technology. It was really impressive to see images of really thin TVs made out of plastic that could be rolled up and placed in your bag or your pocket. I thought that it would take a long time to develop this technology and to see the first TVs available. However it seems that this is about to become true this year, since Panasonic, Sony and LG have announced that the first OLED TVs will be released in 2012 and mass fabrication will be carried out in 2013.

OLEDs provide more efficient devices, brighter images, they are thinner and their contrast is much better than current LCD and plasma technologies. On the other hand OLEDs will be also soon present in lighting. These days the British company Lomox has announced the development of light emitting wallpaper that can be used in the interior of buildings and with time will substitute the classic bulbs. The OLED lighting is much more efficient that current technologies what will introduce significant savings in CO2 emission related with lighting energy consumption.

21 June 2012

A High-performance Thermoelectric "Solar Cell"

Last year researchers from the Massachusetts Institute of Technology (USA) showed that thermoelectrics are an attractive alternative for converting solar energy into electricity. They designed a device that relies on the transformation of light into heat, which is stored in a solar absorber material, and then transformed into electricity by means of a single thermoelectric unicouple of nanostructured Bi2Te3. Unlike solar cells, this device is not based on exciting electron-hole pairs but the sunlight is stored as heat in the solar absorber, providing a very high temperature at the top side of the thermoelements. On the contrary the bottom side is contacted at a Cu heat sink. The whole system is encapsulated in a tube which is evacuated, reducing significantly heat losses and achieving a large temperature difference that is converted into electricity.
The novel Solar Thermoelectric Generator (STEG) shows a peak efficiency of 4.6% (7–8 times higher than previous flat-panel STEG). This new approach has the potential to achieve cost-effective conversion of solar energy into electricity. The video below from the program Science for the Public provides really interesting information about this novel development directly from Prof. Gang Chen, its inventor.

14 June 2012

Dye Sensitized Solar Cells in the iPad

DSCs have become these days a commercial product in the mainstream market in a keyboard developed by Logitech and G24i, the leading company in flexible DSC fabrication in Wales (UK). In the Logitec website it can be seen this innovative Solar Keyboard Folio that integrates in the back side two DSC small modules.

This new product takes advantage of the ability of the DSCs to capture more efficiently the energy from indoor lighting with respect to other photovoltaic technologies. As stated in the product description "The built-in Bluetooth® keyboard is powered by light—low light and lamp light, indoors and out. Fully powered, you can type on it for two years—even in complete darkness".
 After 21 years of intense research since the publication of the nature paper by Grätzel and O'Regan reporting the first DSC, this technology has now arrived successfully to the market. Congratulations to the G24i team for this achievement and all the efforts dedicated to this technology.

13 June 2012

High Efficiency All-solid-state Dye-sensitized Solar Cell

Researchers from Northwestern University in Illinois (USA) have published in Nature a novel solid state Dye-sensitized solar cell (DSC) that shows an outstanding efficiency higher than 10 %, very close to the best DSC value of around 11 % from their liquid counterpart. The cell has the classic structure for the photoanode (FTO/TiO2/dye) and the electrolyte is substituted by a solution processable p-type semiconductor (CsSnI3 doped with SnF).
Up to now, the best solid-state DSCs were made of hole transport materials such as spiro-OMeTAD or bis-EDOT, providing efficiencies around 6 %, whose main problem are related to the poor filling of the nanoporous TiO2 layer. This novel cell proposed by Mercouri Kanatzidis and co-workers fills easily the nanoporous matrix since the hole conductor, dissolved in a volatile organic solvent, is injected directly onto the sensitized photoelectrode. This facile and inexpensive process in addition to the use of abundant elements in the fabrication of the device make this new cell a breakthrough in the solar cell area and a feasible solution to the leaking problems of liquid DSCs.