| Organic semiconductors have been the subject of active research for over a decade because these materials can potentially be fabricated large-area and flexible organic electronic devices at very low cost. Recently, as the typical organic semiconductors, owing to the unique optical, electrical properties, associated with the intriguing intramolecularπ-πinteractions, phthalocyanine, perylene and their derivatives have attracted great attention. The research of them is focused on design and synthesis of the molecule, physical and chemisty properties, the morphology of the materials, the applications of optoelectronics functionality.Our research work has been focused on the following respects:1. Electrochemistry of heteroleptic bis(phthalocyaninato) rare earth(III) complexes.The electrochemistry of a series of heteroleptic bis(phthalocyaninato) rare earth double-decker complexes M(Pc)[Pc(OC8H17)8] [M = Y, Pr-Lu except Pm; H2Pc = phthalocyanine; H2Pc(OC8H17)8 = 2,3,9,10,16,17,24,25-octakis(octyloxy)phthalocy-anine] has been systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). Two quasi-reversible one-electron oxidations and three quasi-reversible one-electron reductions have been revealed for these heteroleptic double-deckers. The half-wave potentials of all the oxidations and the first reduction for double-decker complexes are dependent on the size of the metal center. The difference between the redox potentials of the first and second reductions for M(Pc)[Pc(OC8H17)8], which represents the potential difference between the first oxidation and first reduction of {M(Pc)[Pc(OC8H17)8]}-, lies in the range 1.07-1.25 V and gradually diminishes along with the lanthanide contraction, indicating increasedπ-πinteraction in the double-deckers connected by the smaller lanthanides. This corresponds well with the red-shift of the lowest energy band observed in the electronic absorption spectra of reduced double-decker {M(Pc)[Pc(OC8H17)8]}-. The assignments of the vibration bands for these compounds have been made by comparison with the IR spectra of unsubstituted and in particular the 2,3,9,10,16,17,23,24-octakis(octyloxy)-substituted bis(phthalocya-ninato) rare earth analogues M(Pc)2 and M[Pc(OC8H17)8]2.2. Thin film transistors based on Langmuir-blodgett film of heteroleptic bis(phthalocyaninato) rare earth complexes.Ordered molecular assembly of heteroleptic bis(phthalocyaninato) rare earth complexes M(Pc)[Pc(OC8H17)8] [M = Tb, Lu; H2Pc = phthalocyanine; H2Pc(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] has been fabricated by Langmuir-Blodgett (LB) technique and characterized by surface pressure-area isotherm, electronic absorption and polarized electronic absorption spectroscopy, low-angle X-ray diffraction, and atomic force microscopic. The molecular ordering in the LB multiplayer film on SiO2 substrate was made into a p-channel field effect transistor (FET), which was generally operated in the enhanced mode. The energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as the energy band diagram can be deduced from the electrochemical measurement result. The charge mobilities of Tb(Pc)[Pc(OC8H17)8] and Lu(Pc)[Pc(OC8H17)8] were calculated to be about 6.4×10-4 cm2 V-1 s-1 and 1.7×10-3 cm2 V-1 s-1, respectively.3. Self-Assembled Nano-Structures of Perylene-3,4:9,10-Tetracarboxydiimides with Two Dodecyloxy and / or Thiododecyl Groups at the Bay Positions. Effect of Substituents on the Morphology of Organic Nano-Structure.Three perylene-3,4:9,10-tetracarboxydiimide compounds with two dodecyloxy and / or thiododecyl chains attached at the bay positions of perylene ring, PTCDIs 1-3, have been fabricated into nano-assemblies by a solution injection method. The morphologies of these self-assembled nano-structures were determined by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). PTCDI compound 1 attached with two dodecyloxy groups was revealed to form long and flexible nano-wires with aspect ratio (length over width) over 200 while analogue 3 with two dodecythio groups self-assembled into spherical particles. In line with these results, PTCDI 2 connected with one dodecyloxy group and one thiodocecyl group at each of the two bay positions forms nano-rods with aspect ratio around 20. Both electronic absorption and fluorescence spectroscopic results reveal the formation of H-aggregates in the nano-structures of these PTCDI compounds due to the π-π interaction between the substituted-perylene molecules and meanwhile suggest the decreasing π-π interaction in the order of 1, 2, to 3, which corresponds well with the morphology of corresponding nano-assemblies formed. The effect of different substituents at the bay positions of perylene ring on the π-π interaction between substituted-perylene molecules and the morphology of self-assembled nano-structures formed is rationalized by different degree of twisting of the conjugated perylene system caused by different substituents and different bending manner employed by alkoxy and thioalkyl groups with respective to the plane of naphthalene ring in the molecule, on the basis of DFT calculation results.
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