A team of international researchers at the Department of Energy’s SLAC National Accelerator Laboratory examined the properties of materials that combine graphene with a common type of semiconducting polymer and found that a thin film of the polymer transported electric charge better when grown on a single layer of graphene than it does when placed on a thin layer of silicon.

The scientists claim that their study is one of the first to measure the charge transport in these materials in the vertical direction – the direction that charge travels in organic photovoltaic devices like solar cells or in light-emitting diodes. A somewhat surprising result of the study was that a polymer film about 50 nanometers thick conducted charge about 50 times better when deposited on graphene than the same film about 10 nanometers thick.

The team concluded that the thicker film’s structure forms a continuous pathway of interconnected crystals that allows for easier charge transport than in a regular thin film. By better controlling the thickness and crystalline structure of the semiconducting film, it may be possible to design even more efficient graphene-based organic electronic devices and benefit areas like next-generation photovoltaic devices and flexible electronic devices.