Polymer sticker increases efficiency of solar power cell by about 10%, and other developments

Over the next four-five decades, the growing energy demands of the world�s population will be supplied without using fossil fuels. The sun is a key renewable energy source and needs to be harnessed on a larger scale. New developments in solar panel films, cheap and efficient polymer solar cells, etc are leading the way.
The power output of solar panels can be boosted by 10% just by applying a big transparent sticker to the front. A small company called Genie Lens Technologies has developed a transparent sticker embossed with micro structure that bends incoming light radiation which results into solar cell absorbing more light and thus convert more energy into electric power. This film can be installed on the existing panel to improve its efficiency. The film has essentially three functions: They are:
• Prevent light from reflecting off the solar panel
• Trapping more sunlight inside the semi conductor material which results into higher absorption of light.
• Redirect incoming light r so that rather than passing through the thin semiconductor material, it travels along its surface, increasing the chances it will be absorbed.
Researchers of Genie Lens Technologies worked on model to ensure that light radiation enters into semiconducting material throughout the day both from solar panel front and back surface of the panel. The key was bending the light the optimal amount, enough that it enters the solar panel at an angle, but not so much of an angle that the light reflects off and is lost. If light does reflect off either the glass or semiconductor surfaces, the film redirects much of it back into the solar panel. Tests at the National Renewable Energy Laboratory showed that the film increases power output on average of 10-12.5%. This film gives best results under cloudy conditions, when incoming light is diffuse. This film increases cost by about 2-10%. Additional savings can be made as increasing the power output of a solar panel decreases other costs-such as shipping and installation, because fewer solar panels are required at each installation. If the film is scratched, attracts dust, or becomes discolored after years or decades in the sun, it could actually lower power output over time. Though claimed films will to last for 20 years, their durability hasn't been verified.
Swiss scientists have broken an energy conversion efficiency record for flexible thin-film CIGS solar cells. In collaboration with the Swiss solar start-up Flisom, Empa (Swiss Federal Laboratories for Materials Science and Technology) has achieved 18.7% efficiency for CIGS (copper indium gallium selenide) flexible solar cells, which the lab says was made possible by mounting them on a polymer substrate. The latest improvements in cell efficiency were made possible through a reduction in recombination losses by improving the structural properties of the CIGS layer and the proprietary low-temperature deposition process for growing the layers as well as in situ doping with Na during the final stage. With these results, polymer films have for the first time proven to be superior to metal foils as a carrier substrate for achieving highest efficiency. This breaks Empa's record of 17.6% when mounting the CIGS on steel foil substrates, according to the Swiss lab. Solar efficiency is the amount of electricity per square inch that can be gleaned from a solar cell. While traditional silicon cells are generally more efficient that CIGS cells, CIGS cells have some advantages. Flexible CIGS can be made via roll-to-roll processing in which the cells are "printed" or patterned on giant rolls of flexible material, which makes them less expensive to manufacture than traditional cells. Because CIGS can be made flexible and are generally lighter than silicon panels, they offer more options on how they can be installed and what kind of frames or supports are needed, and can be less expensive to ship.
A new study shows that even when using very simple and inexpensive manufacturing methods - where flexible layers of material are deposited over large areas like cling-film - efficient solar cell structures can be made. The study, published in the Journal Advanced Energy Materials, paves the way for new solar cell manufacturing techniques and the promise of developments in renewable solar energy. Scientists from the Universities of Sheffield and Cambridge used the ISIS Neutron Source and Diamond Light Source at STFC Rutherford Appleton Laboratory in Oxfordshire to carry out the research. Plastic (polymer) solar cells are much cheaper to produce than conventional silicon solar cells and have the potential to be produced in large quantities. The study showed that when complex mixtures of molecules in solution are spread onto a surface, like varnishing a table-top, the different molecules separate to the top and bottom of the layer in a way that maximises the efficiency of the resulting solar cell. The results give important insights into how ultra-cheap solar energy panels for domestic and industrial use can be manufactured on a large scale. Rather than using complex and expensive fabrication methods to create a specific semiconductor nanostructure, high volume printing could be used to produce nano-scale (60 nano-meters) films of solar cells that are over a thousand times thinner than the width of a human hair. These films could then be used to make cost-effective, light and easily transportable plastic solar cell devices such as solar panels. This work clearly illustrates the importance of the combined use of neutron and X-ray scattering sources such as ISIS and Diamond in solving modern challenges for society. Using neutron beams at ISIS and Diamond�s bright X-rays, the team was able to probe the internal structure and properties of the solar cell materials non-destructively. By studying the layers in the materials which convert sunlight into electricity, we are learning how different processing steps change the overall efficiency and affect the overall polymer solar cell performance.