Direct Correlation of Organic Semiconductor Film Structure to Field‐Effect Mobility

Near-edge X-ray fine structure spectroscopy is used to measure simultaneous chemical conversion, molecular ordering, and defect formation in soluble oligothiophene precursor films. Film structure is correlated to OFET performance. Molecular orientation is determined by evaluating antibonding orbital overlap with the polarized electric field vector of incident soft X-rays (see Figure and cover). Upon conversion, the molecules become vertically oriented, allowing π overlap in the plane of hole transport.