Geometry and electronic coupling in perylenediimide stacks: mapping structure-charge transport relationships.

The binding energy and electronic coupling of perylenediimide (PDI) pi-stacked dimers were calculated using M06-2X/6-31++G** as a function of stacking geometry. Due to shallow minima in the potential energy surface, electronic coupling can vary by over an order of magnitude among energetically accessible geometries. The coupling was then determined for 20 PDI derivatives with various substitutions at the imide region, and several were identified as the most promising candidates for organic thin film transistors (OTFTs). This strategy of side-by-side comparison of binding energy and electronic coupling may prove useful for other pi-stacked OTFTs such as pentacene and poly(thiophene) derivatives.