Finding the Traps in Organic Semiconductors

Category: Science & Technology
Posted: July 30, 2012 11:00AM
Author: Guest_Jim_*

Plastics are wonderful materials as different polymers can have so many different properties, yet are potentially cheap to mass produce. This is why we see researchers trying to bring the materials into many technologies, such as electronics, but there are several issues impairing their adoption. For organic semiconductors an issue is the trapping of electrons within the material, which causes energy to be lost. Researchers at the Georgia Institute of Technology and University of Groningen have studied these traps and believe they have found the problem.

Semiconductors exist between insulators and conductors because of what is known as the band gap. If an electron does not have enough energy to jump the gap, it remains attached to its atom, but if the electron does have enough energy it will exist in the conduction band, where it will be able to move to other atoms, like in a conductor. The traps in organic semiconductors allow the electrons to fall to an energy level within the band gap, so it no longer conducts but still has more energy than if it fell completely through the band gap.

The researchers believe this is because of water-oxygen complexes within the semiconductors. Even though the materials were made in a nitrogen environment, some water vapor and oxygen likely leaked in and there is little to nothing that can prevent that. Fortunately though, the researchers believe there is a way to fix the traps. By creating polymers with shorter band gaps, the traps' energy levels could be above that of the conducting electrons, so they cannot fall in.

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