Solution-processed zinc tetrabenzoporphyrin thin-films and transistors

Thin-films and organic field-effect transistors fabricated from a solution-processable precursor of zinc tetra-benzoporphyrin (ZnTBP) are reported. Amorphous, insulating precursor films were deposited by spin-casting and thermally converted into polycrystalline, semiconducting thin-films comprising grains on the order of 51 mu m in diameter. Thin-film X-ray diffraction indicates a monoclinic unit cell with molecules arranged in a herringbone pattern, which in conjunction with optical and atomic force microscopy indicate a thin-film with grains comprised of randomly oriented ZnTBP aggregates. Optical absorption measurements display broad absorption with bands characteristic of a D-4h symmetric porphyrin molecule. Organic field-effect transistors displayed field-effect mobilities on the order of 10(-2) cm(2)/V s and ON-/OFF-current ratios exceeding 10(2). (C) 2012 Elsevier B.V. All rights reserved.