The field of organic electronics has benefited from the discovery of new semiconductor polymers with molecular backbones that are resilient to twisting and bending, meaning they can transport charges even when they bent into different shapes.
These materials are thought to be like a plate of spaghetti at the molecular scale, without any long-range ordering. However, an international team of researchers has found that for at least one such material, there are small orderly compartments inside. These ordered bags, which are only a few tenths of a billion meters across, are stiffer than the rest of the material, giving it a ‘left wheel’ structure with stiffer and softer zones.
The work was led by the University of Cambridge and Park Systems UK Limited, with KTH Stockholm in Sweden, the Universities of Namur and Mons in Belgium, and Wake Forest University in the United States. Of them resultreported in the journal Nature Communicationscan be used in the development of next-generation microelectronics and bioelectronic devices.
Organic polymer membranes. A region showing parallel alignment of individual polymer chains confirms the nanoorder. Such organization is not visible in the disordered region. Image credit: University of Cambridge
Studying and understanding the mechanical properties of these materials at the nanoscale – a field known as nanomechanics – can help scientists refine those properties and make materials suitable with more applications.
Dr Deepak Venkateshvaran from Cambridge’s Cavendish Laboratory, who led the study, said: “We know that nature’s structure on the nanoscale is not uniform, but finding uniformity and order. which we didn’t expect to see it as a surprise.
The researchers used an imaging technique called higher electron coding imaging to take nanoscale images of ordered regions inside a semiconductor polymer called indacenodithiophene-co-benzothiadiazole (C16). -IDTBT). These images clearly show how the individual polymer chains line up next to each other in several regions of the polymer film. Regions of this order are 10 to 20 nanometers across.
Co-author Dr Leszek Spalek, also from Cavendish Laboratories, said: “The sensitivity of these detection methods allows us to map the self-organization of polymers to individual molecular fibers. “Higher eigen mode imaging is a valuable method for characterizing the nanomechanical properties of materials, due to the relatively easy sample preparation required.”
Further measurements of the material’s stiffness at the nanoscale show that the regions where the polymer self-organizes into ordered regions are stiffer, while the disordered regions of the material are softer. The experiments were performed under ambient conditions as opposed to an ultra-high vacuum, which was required in earlier studies.
“Organic polymers are often studied for their applications in large area, centimeter-scale, flexible electronics,” said Venkateshvaran. “Nanomechanics can enhance these studies by developing an understanding of their mechanical properties at microscopic scales with unprecedented resolution.
“Together, the fundamental knowledge gained from both types of research could inspire a new generation of bioelectronic and soft microelectronic devices. These futuristic devices will combine the benefits of centimeter-scale flexibility, micrometer-scale uniformity, and nanometer-scale electrically controlled mechanical movement of polymer chains with compatibility superior biology. ”
Source: University of Cambridge
