Organic Semiconductor Spherulites on Front Cover of JACS
In single crystals of organic semiconductors, charge carrier mobility can depend strongly on the crystal orientation, since mobility is typically much higher along the pi-stacking direction. But usually, the active layer in organic transistors consists not of a single crystal, but of a polycrystalline aggregate. CBE graduate student Stephanie Lee, working with Professor Yueh-Lin Loo and collaborators from the University of Kentucky, has studied large two-dimensional spherulites—radially-symmetric polycrystalline structures—of the organic semiconductor TES-ADT, and found that the mobilities of transistors are surprisingly independent of the general pi-stacking direction, due to the low-angle grain boundaries that are ubiquitous in spherulites. The March 28 issue of Journal of the American Chemical Society includes a Communication describing this work, and the issue’s front cover features a striking image of multiple transistors spanning a single spherulite.