Disordered molecules plastic solar cells can improve the performance of

Scientists found disordered at the molecular level can actually improve polymer properties. Now, researchers at Stanford University have made the surprising discovery of this explanation. This finding is bound to accelerate the low-cost commercial plastic solar cell development.

To develop work with conventional silicon cells under a high efficient soft plastic solar cells, scientists have spent decades time. Currently, research groups have tried to create new plastic material, by enhancing the current solar cell to improve battery performance. Some research groups re flexible plastic polymer design to silicon in an orderly class, but the current has not been increased.

"People used to think that as long as the structure of the polymer more like silicon, their performance will improve." Co-author of the study and Stanford University associate professor of materials science and engineering AlbertoSalleo said, "but we found that the polymer can not form naturally beautiful, orderly crystals, they can only form a small disordered crystals, and these can just solve our technical problems. "

Salleo and colleagues suggest that scientists do not attempt to simulate the rigid structure of silicon, but to learn to understand the nature of the disorder plastics.

High-speed electronic

In the study, Stanford University team will focus on a class called conjugated semiconducting polymers or organic material that has a plastic performance and the ability to absorb light and electrical conductivity.

Semiconducting polymers was discovered 40 years ago, and was long considered to be ultra-thin small solar cells , light-emitting diodes and transistors ideal material. With rooftop solar panels using silicon crystal is different semiconducting polymers lightweight structure and can be used at room temperature, low-cost inkjet printers and other technology for processing. However, it has not been commercialized is a major cause of poor performance. Electron solar cell needs to move quickly in the material, and the semiconductor polymer is a low electron mobility.

X-ray analysis

In order to observe the micro level disordered materials, Stanford University research team at SLAC National Accelerator Laboratory of the samples were characterized by X-ray analysis. Analysis showed that the molecular structure of the semiconductor polymer resembling a distorted fingerprint. Some amorphous polymer that looks like spaghetti, while others are only a few molecules long tiny crystals.

By analyzing the current through the sample and the emission situation, the team concluded that numerous small crystals dispersed throughout the material by a long polymer chains connected together like beads on a necklace the same. The crystal size is crucial to improve the performance of the material.

The small size of the charged electron crystal can quickly move to the next crystal, so long polymer chains can be carried through the material quickly Electronics. This explains why they are bigger than the size of the crystal is not connected to the high charge mobility.

Another major disadvantage of the crystalline polymer is that it can result in non-soluble by an ink jet printer or other processing technology to produce low cost.

Therefore, they finally concluded that, to improve the battery performance without the formation of large crystals of the steel material, but the need to design small size unordered be closely linked to the polymer chain crystalline material.