Scientists have discovered a method using polymers that could allow improved solar cells to be manufactured more cheaply and with more flexibility.
Manufacturers already print or roll material onto surfaces to produce an electronically functional device, writes Jennifer Hicks in Forbes. This process is used to make organic solar cells and organic light-emitting diodes that go into displays on mobile phones.
These devices offer advantages over conventional silicon- or semiconductor-based electronics because they can be more flexible, irregularly shaped, and lighter in weight, reports Mitch Jacoby for Chemical & Engineering News. However, organic electronic devices tend to remain expensive because some of the manufacturing steps require vacuum processing to prevent the component materials — calcium, magnesium, and lithium — from reacting with oxygen and moisture. This is why electronics in solar cells or TVs are often covered with rigid, thick plates of glass or encapsulating layers.
Now, a team of scientists from the Georgia Institute of Technology (Georgia Tech) have developed a method to eliminate this problem. They spread a layer of polyethylenimine or ethoxylated polyethylenimine one to 10 nanometers thick onto a conductor’s surface. The application turns the air-stable conductors into efficient, low-work function electrodes. The polymers are commercially available and are diluted in solvents before applied.
Bernard Kippelen, professor at Georgia Tech’s Center for Organic Photonics and Electronics, says:
Replacing reactive metals like lithium and calcium with stable conductors, including conducting polymers, completely changes the requirements of how electronics are manufactured and protected and paves the way for lower cost and more flexible devices. This technique is based on the printing of organic inks that have semiconducting properties that can be processed at temperatures below 200 C. This allows for the fabrication of electronics devices onto plastic or even paper substrates.
Plastic solar cells could eventually be made cheaper than crystalline silicon solar cells, but issues remain. Kippelen adds:
The goal is to reach a price point for a photovoltaic module that is below the cost of the raw silicon that is used to fabricate conventional silicon solar cells. But the road to get there is still long and the new printable electrodes and the demonstration of a completely plastic solar cell are only a small step in the right direction towards this challenging objective.
Source: “New Technique Creates First Plastic Solar Cell,” Forbes, 4/25/12
Source: “Electrodes By Solution Processing,” Chemical & Engineering News, 4/23/12
Image by Snowacinesy, used under its Creative Commons license.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.
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