One thing we know about solar cells is that thinner it is less expensive it gets; thin film solar is cheaper than the standard silicon cells. Stanford University’s team of Researchers has come up with Solar cells thinner than the wavelengths of light which are also more efficient! They say Ultra-thin solar cells can absorb sunlight more efficiently than the thicker, more expensive-to-make silicon cells used today, because light behaves differently at scales around a nanometer (a billionth of a meter).
The team consists of Shanhui Fan, associate professor of Electrical engineering and postdoctoral researcher Zongfu Yu who is the lead on the PNAS paper. Aaswath Raman, a graduate student in applied physics, also worked on the research and is a coauthor of the paper.
Everyone worked with the assumption that light travels in a straight line i.e. if a ray of light hits a mirror it bounces back as another ray. When Yu began investigating the behavior of light inside a material of deep subwavelength-scale – substantially smaller than the wavelength of the light – that it became evident to him that light could be confined for a longer time, increasing energy absorption beyond the conventional limit at the macroscale. On further research Yu figured out that he could increase absorption rate by 12% by sandwiching the organic thin film between two layers of material – called “cladding” layers – that acted as confining layers once the light passed through the upper one into the thin film. Atop the upper cladding layer, he placed a patterned rough-surfaced layer designed to send the incoming light off in different directions as it entered the thin film.
The project was supported by funding from the King Abdullah University of Science and Technology, which supports the Center for Advanced Molecular Photovoltaics at Stanford, and by the U.S. Department of Energy.
Source – The Stanford News
Source of Picture www.inhabitat.org
Solar panels in the market now only have an efficiency of up to 15% at the maximum, most are between10-12% normally. That means only 10-12% of the sun light is being utilized now. Scientists have been working hard to find a way to increase the efficiency by shaping the panels differently, using mirrors etc… Now RoseStreet Labs has managed to increase the efficiency 3 fold! They have created a solar cell which uses 3 different layers of Photo Voltaic cells in a single layer thin-film solar panel to capture different spectrum’s of the Sun’s radiation.
RoseStreet Labs Energy Inc.(RSLE) had this to say in a press release dated Sept 29th 2009 “RoseStreet Labs Energy, Inc. (RSLE) announced today a breakthrough demonstration of the first known Nitride/silicon tandem solar cell. Utilizing the same Nitride material technology as solid state lighting and blue lasers, RSLE fabricated and tested a working photovoltaic cell that couples a silicon solar cell with a Nitride Thin Film. This is a major milestone in RSLE’s product roadmap to achieve substantially higher solar efficiencies than standard silicon or other thin film solar cells.”
They used their IBand technology to achieve this new development and are the first to do so. The idea of integrating three bands — each band capturing a different part of the spectrum — has been around for a while but this is the first proven success. RSLE’s demonstration device was fabricated on high volume CVD technology, validating the potential for high volume commercialization. The company says this technology illustrates great promise for high efficiency thin film solar efficiencies above 35% by potentially capturing the full spectrum of the sun’s spectrum.
Read the first Press Release by RoseStreet Labs Here
Read Related articles about it at Renewable Energy World or Inhabitat
An Interesting read about Thin Film Solar:
Thin Film Solar Cells: Fabrication, Characterization and Applications