[amor de cosmos]

Cheaper Chinese solar panels are not due to low-cost labour
05 September 2013

A study of the photovoltaic industries in the US and China shows that China's dominance in solar panel manufacturing is not driven solely by cheaper labour and government support, but by larger-scale manufacturing and resulting supply-chain benefits.

But the researchers say a balance could be achieved through future innovations in crystalline solar cell technology, which have the potential to equalise prices by enhancing access to materials and expanding manufacturing scale across all regions.

The study is published today in the Royal Society of Chemistry journal Energy & Environmental Science.

Researchers at the US Department of Energy's National Renewable Energy Laboratory (NREL) and Massachusetts Institute of Technology (MIT) developed a bottom-up cost model to examine the underlying causes for the shift in the global manufacturing base of photovoltaics from the US and Europe to China.

http://www.rsc.org/AboutUs/News/Pres...ost-labour.asp

Laser Spectroscopy Helping to Measure Progress in Nanotech Design
PHILADELPHIA, September 3, 2013

Engineers working in the nanoscale will have a new tool at their disposal thanks to an international group of researchers led by Drexel University’s College of Engineering. This innovative procedure could alleviate the persistent challenge of measuring key features of electron behavior while designing the ever-shrinking components that allow cell phones, laptops and tablets to get increasingly thinner and more energy efficient.

“The interface between two semiconductor materials enables most of the electronic gadgets we use each day, from computers to mobile phones, displays and solar cells,” said Guannan Chen, a graduate student in Drexel’s Materials Science and Engineering department and the lead author of the group’s report, which was recently published in Nano Letters. “One of the most important features of the interface is the height of the energy step required for the electron to climb over, known as band offset. Current methods for measuring this step height in planar devices are not practical for nanoscale devices, however, so we set off to find a better way to make this measurement.”

Measuring the band offset faced by electrons jumping from one material to another is a key component of the design process because it guides the redesign and prototyping of nanoscale components in order to make them as efficient and effective as possible.

Using laser-induced current in a nanowire device and its dependence on the wavelength of the laser, the team devised a new method to derive the band offset. As they continuously change the wavelength of the laser, they measure the photocurrent responses. From this data they are able to determine the band offset.

“Using the interface within a co-axial core-shell semiconductor nanowire as a model system, we made direct measurements of the band offset for the first time in nanowire electronics,” Chen said. “This is a significant cornerstone to freely design new nanowire devices such as solar cells, LEDs, and high speed electronics for wireless communications. This work can also extend to broader material systems which can be tailored for specific application."

http://drexel.edu/now/news-media/rel...ing-band-gaps/