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.