Cover Picture: Direct Correlation of Organic Semiconductor Film Structure to Field‐Effect Mobility (Adv. Mater. 19/2005)

The use of near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy as a non‐destructive technique to quantify the simultaneous chemical conversion, molecular ordering, and defect formation of soluble oligothiophene precursor films intended for application in organic field‐effect transistors is demonstrated on p. 2340 by DeLongchamp and co‐workers. Illustrated from left to right, with increasing temperature: a) as‐cast, the molecules are weakly oriented; b) at the conversion onset, they become isotropic; c) after full conversion, they are strongly oriented and exhibit maximum field‐effect mobility; and d) overheating reduces film coverage and decreases their orientation, thus lowering their performance.