News Solar briefs US researchers at North Carolina


State University have discovered that controlling the mixing between the acceptor and donor layers, or domains, in polymer-based solar cells could increase their efficiency. It had been believed that keeping the two layers as pure as possible ensured that the excitons, the energy particles produced by sunlight hitting the cells, travelled unimpeded to the interface between the layers, thereby capturing the most amount of energy. Working with researchers in the UK, Australia and China, the researchers are looking at the most effective mix of solvents and additives used to manufacture the cells (Advanced Materials, doi: 10.1002/adma.201202855; Advanced Energy Materials, doi: 10.1002/ aenm.201200377).


The partners in the Solliance initiative,


including Belgian nano-electronics research organisation imec, together with the Institute of Materials Research of the University of Hasselt, which has two campuses in Belgium, have launched the Solar Flare Interreg Project, designed to focus on the development of CIGS and other thin-film photovoltaic technology to produce similar efficiencies to those of conventional silicon cells of around 17%.


Researchers within the project


group for fiber optical sensor systems at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz- Institut, in Berlin, Germany, have used black silicon to capture the infra-red radiation that is normally lost with conventional silicon cells, thereby increasing their efficiency to 18%. Black silicon is produced by irradiating normal silicon with femtosecond laser pulses in an environment containing sulphur.


Microwave technology has been used by scientists at Oregon State University, US, in the synthesis of copper zink tin sulphide, which can be used to manufacture thin film solar cells. This synthesis method is said to be faster, cheaper and less energy intensive than conventional heating, and has been used to produce nanoparticle inks that can be printed to produce the solar cells.


Asia energy China restarts nuclear build Maria Burke


China is to restart its programme to construct nuclear reactors, which had been suspended since March last year following the Fukushima disaster in Japan. After acknowledging safety concerns in some of its facilities, China says it will spend 80bn yuan ($12.74bn) by 2015 to upgrade security and radioactive contamination control to international standards. The government is to allow a ‘small number’


of reactors to be built before 2015, according to the official website. New reactors would have to meet the ‘world’s highest safety requirements’ and would have to comply with ‘third-generation’ safety standards. However, no mention was made of when construction would restart.


The


statement, from a


meeting of the State Council, the


country’s highest executive body chaired


by Premier Wen Jiabao, stressed that ‘safety Materials science Plasters without the pain Kathryn Roberts


Removing a medical plaster from the fragile skin of the elderly or newborn babies sometimes can cause serious injury. Researchers in the US have taken a cue from nature by designing a quick- release medical tape with strong adhesion properties but without the ‘ouch factor’. Jeffrey Karp, senior biomedical engineer at Brigham and Women’s Hospital in Boston, US, in collaboration with medical scientists at the Massachusetts Institute of Technology (MIT)


14 Chemistry&Industry • November 2012


sought to mimic the easily peeled and highly shear-resistant multi- laminate structure of the silicate mineral, mica. This led them to a three-layer design (PNAS, doi:10.1073/pnas.1216071109). Traditionally, medical tapes have two layers – an adhesive on a backing material – which fracture at the adhesive–skin interface. While the backing has a protective role, it also contributes to the increased force required to remove the tape. ‘Our approach transitions the fracture zone away from the skin to the adhesive-backing interface, thus


completely preventing any harm during removal’, says Karp. The new design incorporates an intermediate layer between the backing and the adhesive layer. By using laser etching, the researchers create an ‘anisotropic’ interface between the backing and the adhesive layers. In one direction the tape has high shear strength for strong adhesion, and in the other low peel force for safe, quick removal. The new tape rapidly decouples the backing from the adhesive layer without compromising the adhesive–skin interface.


is the lifeline’ of nuclear power. China will ‘improve the safety performance’ of existing units and those under construction. It wants to strengthen all aspects of nuclear safety management, including emergency management and response capabilities. At present, there are 15 operating nuclear power units in mainland China. China’s target is to increase nuclear capacity to 40GW by 2015, and to 70–80GW by 2020, up from 12 GW today. It has 26 reactors currently under construction. Earlier in October, a report by China’s Ministry


of Environmental Protection acknowledged safety concerns in China’s fleet of nuclear reactors. The report notes the number of reactor models in operation makes nationwide safety standards and emergency-response mechanisms more complicated. Prior to Fukishima, China was ordering and constructing large numbers of reactors, says energy expert Antony Froggatt of Chatham House, London. ‘So the announcement that a small number will be built is significant in terms of numbers, but also because these new reactors will be third generation models with higher safety standards. It is good that they are looking at the lessons of Fukishima and taking steps to improve safety.’ Around 40% of all nuclear reactors under construction globally are in China, says Frogatt, but nuclear provides only 1–2% of its electricity mix. ‘With the rate at which energy demand is increasing, nuclear is always going to be marginal. Moving away from coal consumption is going to require huge changes.’


Find C&I online at www.soci.org/chemistryandindustry


Justin Guariglia/Getty


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