Plastic solar panels

A new method for producing electrically conductive plastic materials developed by engineers from Princeton University could significantly reduce the production costs of solar panels.

After overcoming technical challenges to produce transparent, designable and electrically conductive plastic materials, the researchers paved the way for a more practical use of the material for a wide range of electrical devices.
In light of the growing concerns about global warming and the increase in the demand for energy, plastic materials could be a cost-effective alternative to tin-indium oxide, an expensive conductive material currently used in solar panels - according to the researchers.

"Conducting polymers (plastics) have been around for a long time, but processing them into useful components has impaired their ability to conduct electricity," said Yueh-Lin Loo, a professor of chemical engineering at Princeton University. "We were able to figure out how to avoid this failure. We can shape the plastic materials into a useful form while maintaining their high electrical conductivity." The research findings were published in the scientific journal Proceedings of the National Academy of Sciences.

In the field of research, known as "organic electronics", since plastic is based on carbon, similar to living things, there is potential for developing new types of electronic devices and new methods for producing existing technologies. However, the progress of this field has been hindered by the mysterious loss of conductivity in the finished processed products.

"The researchers did not understand what was happening here," says the scientist. "We discovered that when the polymers are designed, their structures are trapped in a rigid pattern that prevents the electric current from moving through them."
Once they understood the basic problem, the researchers developed a method to soften the plastic structure by treating it with acid after shaping it into the desired pattern.

Using the method, the researchers were able to create a plastic transistor - a key component in electronics used to amplify and transmit electrical signals. They produced the electrodes of the transistor by embedding the plastic into a surface - a quick and cheap method similar to the way an ink-jet printer produces a print on paper.

The researcher stated that the method can be transferred to an industrial scale for commercial production, similar to the printing presses used today to print newspapers. "The ability to "paint" on electronic components, which is actually how our method works, is an important success," says the researcher. "You can sell the plastic in cartridges similar to the way printer ink is sold, and you won't need special machines to print the desired patterns."

Following the possibility of producing solar cells from plastic by cost-effective printing methods and by replacing the main and expensive conductive material tin-indium oxide, the plastic developed by the researchers has the potential to reduce the price of solar panels.

Today, the electricity generated by plastic solar cells is transmitted through a transparent metallic conductor composed of tin-indium oxide. The conductor must be transparent to allow the sun's rays to pass through it and reach the materials that make up the solar cell whose function is to absorb the sun's energy. The oxide, which is a rare and expensive by-product obtained from mining processes, has become a sought-after material for use in flat-screen televisions, mobile phones and other devices with display screens. "The price of this material is skyrocketing," said the researcher. "In order to reduce the price of plastic solar cells we need to find alternative materials for this oxide. Our conductive plastic allows sunlight to pass through, a fact that makes it an effective alternative."

The researchers anticipate that their plastic could also replace expensive metals currently used in other electronic devices such as flexible displays. In addition, the scientists are beginning to test the use of the plastic in biosensors that will emit a certain color as soon as a person has an infection. For example - the plastic will change its color from yellow to green when exposed to nitrous oxide, a chemical substance that is formed during ear infections in children.

If these devices can be produced at a low cost, they could be useful in developing countries where advanced medical facilities do not exist. "You won't need expensive machines or laboratory equipment to detect contamination and diseases," explains the researcher, "all that is needed is our eyes to notice the change in the color of the plastic."

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