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February 05, 2010

Nano-patterning Provides Large Boost for Solar Cells and Other Solar Improvements

1. Advanced Functional Materials - Poly(3-hexylthiophene) Nanorods with Aligned Chain Orientation for Organic Photovoltaics

A structured polymer solar cell architecture featuring a large interface between donor and acceptor with connecting paths to the respective electrodes is explored. To this end, poly-(3-hexylthiophene) (P3HT) nanorods oriented perpendicularly to indium tin oxide (ITO) glass are fabricated using an anodic aluminum oxide template. It is found that the P3HT chains in bulk films or nanorods are oriented differently; perpendicular or parallel to the ITO substrate, respectively. Such chain alignment of the P3HT nanorods enhanced the electrical conductivity up to tenfold compared with planar P3HT films. Furthermore, the donor/acceptor contact area could be maximised using P3HT nanorods as donor and C60 as acceptor. In a photovoltaic device employing this structure, remarkable photoluminescence quenching (88%) and a seven-fold efficiency increase (relative to a device with a planar bilayer) are achieved.

3 page pdf with supplemental information

Ars Technica has coverage

While the absolute efficiency of the new array—just 1.12 percent—is not cutting edge, the patterning technique is cheap and can be done on a large scale, and is unlikely to be limited to just this material system. Other recent polymer cells have claimed efficiencies of 5.5 percent, for example, and the micro- and nano-pillar approach works with traditional photovoltaic materials, too. There is still much work to be done in the optimization of the processing conditions, but this is yet another piece of the puzzle that may make polymer solar cells a viable option for power generation.


2. Nanowerk - Quantum dot polymer hybrids greatly improve the efficiency of organic solar cells

Researchers were able to attain an efficiency of 2 percent by using so-called quantum dots composed of cadmium selenide. These measurements, well above the previous efficiency ratings of 1 to 1.8 percent.

Organic solar cells belong to the so-called third generation of solar cells and are still in the developmental stage. The world record for purely organic solar cells, a type in which both components of the photoactive layer consist of organic materials, is currently at 7 percent for layers created through wet chemical methods. Organic solar cells have many advantages over the conventional silicon cells typically used for large-scale energy production: Not only are they are considerably thinner and more flexible, they are also less expensive and quicker to produce. They are thus better suited for powering everyday devices and systems which are not in constant use, such as sensors or electrical appliances. In the long run, organic solar cells could drastically reduce our dependence on batteries and cables.

The cost of solar power could be cut 30 percent without improving the performance of individual solar cells, says Daniel Alcombright, vice president for North America at Solon Corporation

* highly-paid electricians spend hours constructing assemblies for conduits, when such things could be built for less in a factory.
* Larger solar modules with quick mount frames could also reduce overall construction costs.
* standardized plans for solar farms, so that each new project doesn't have to be engineered anew.
*low cost tracking systems and software for optimizing their performance in different locations and from season to season could increase power output from the same solar panels.






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