A more efficient way to transport electrical charge has been discovered by a team of researchers. Led by David Barbero of Sweden’s Umeå University, it was discovered that semiconducting polymers, placed on a layer of graphene, transport electrical charge more efficiently than when placed on a silicon substrate.
When placed on a graphene substrate, there is a change in the crystallinity of the semiconducting polymers. The change affects the materials’ electronic properties. Graphene enhances the charge transport through the polymer film, which makes it possible to produce more efficient electronic devices.
Synchotron x-ray diffraction was used to study how crystals are formed in a thin film of semiconducting polymers (plastic) on top of a layer of graphene. The results were then compared with a polymer film on a silicon substrate. The results show an enhanced vertical charge transport in the graphene solution.
An additional discovery of the study was that the charge carrier mobility of a thicker polymer film (50nm) was approximately 50 times higher than in the case of an ultra-thin polymer film (10nm) deposited on graphene. A study of the crystallinity of these layers showed that the 10nm film formed ‘a well-oriented face-on and edge-on lamellae’, while the thicker film formed ‘a mosaic of lamellae at different angles from the graphene substrate’. It is believed that the crystallites formed at different angles lead to the increased efficiency in charge transport and carrier mobility.
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Definition:
A lamella is a thin, plate-like structure with open space between itself and others.
