Inside Front Cover: Nanoscale Surface Morphology and Rectifying Behavior of a Bulk Single‐Crystal Organic Semiconductor (Adv. Mater. 12/2006)

Local surface measurements of rubrene single crystals reveal interesting insights on carrier‐transport mechanisms at the active interface of high‐performance field‐effect “air‐gap stamp” transistors, as reported by Fichou, Rogers, and co‐workers on p. 1552. Scanning tunneling microscopy (STM, tip shown schematically) images, combined with atomic force microscopy and X‐ray diffraction, reveal directly the position and orientation of individual molecules in the a–b plane. Local current–voltage curves recorded using STM in the dark and under illumination indicate a rectifying p‐type behavior.     

Approaching Intra‐ and Interchain Charge Transport of Conjugated Polymers Facilely by Topochemical Polymerized Single Crystals

Charge transport of small molecules is measured well with scanning tunneling microscopy, conducting atomic force microscopy, break junction, nanopore, and covalently bridging gaps. However, the manipulation and measurement of polymer chains remain a long‐standing fundamental issue in conjugated polymers and full of challenge since conjugated polymers are naturally disordered materials. Here, a fundamental breakthrough in generating high‐quality conjugated‐polymer nanocrystals with extended conjugation and exceptionally high degrees of order using a surface‐supported topochemical polymerization method is demonstrated. In the crystal the conjugated‐polymer chains are extended along the long axis of the crystal with the side chains perpendicular to the long axis. Devices with conducting channels along the polymer chains show efficient charge transport, nearly two orders of magnitude greater than the interchain charge transport along the π–π stacking direction. This is the first example to clarify intra‐ and interchain charge transport based on an individual single crystal of conjugated polymers, and demonstrate the importance of intrachain charge transport in plastic electronics.