6533b827fe1ef96bd12865c8

RESEARCH PRODUCT

Self-assembled aggregates of amphiphilic perylene diimide-based semiconductor molecules: effect of morphology on conductivity.

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Abstract Two amphiphilic perylenetetracarboxylic diimide derivatives modified with different side chains at imide nitrogen, N- n -hexyl-N′-(2-hydroxyethyl)-1,7-di(4′-t-butyl)phenoxy-perylene-3,4:9,10-tetracarboxylic diimide ( PDI 1 ) and N,N′-di(2-hydroxyethyl)-1,7-di(4′-t-butyl)phenoxy-perylene-3,4:9,10-tetracarboxylic diimide ( PDI 2 ), were fabricated into organic nanostructures via solution-phase self-assembly. Their self-assembling properties in methanol and n -hexane have been comparatively studied by electronic absorption, fluorescence, and Fourier transform infrared spectroscopy (FT-IR). The morphologies and structures of the self-assemblies were examined by scanning electronic microscopy (SEM), atomic force microscopy (AFM), as well as X-ray diffraction (XRD) techniques. The conducting properties were evaluated by current–voltage ( I – V ) measurements. Due to the presence of different number of hydroxyethyl groups in the molecule of PDI 1 and PDI 2 , the self-assembly of the two molecules in methanol and n -hexane results in nanostructures with distinctly different morphology as follows: nanobelts and nanoleaves for PDI 1 and nanobelt dendrites and nanosheets for PDI 2 , respectively. Analysis of the spectral change for the aggregates relative to that of monomeric PDI in solution revealed that in polar and apolar solvents, both nanobelts and nanoleaves precipitated from PDI 1 adopt the H aggregation mode, whereas nanobelt dendrites and nanosheets from PDI 2 adopt H and J aggregation mode, respectively, implying the effect of both side-chain substituent and solvent on tuning the intermolecular stacking. Furthermore, the conductivity of the aggregates of either PDI 1 or PDI 2 from methanol is more than ca. 1 order of magnitude higher than those from n -hexane. In particular, the well-defined, one-dimensional (1D) nanobelts of PDI 1 show excellent semiconducting property with the electrical conductivity as high as 3.3 × 10 −3  S cm −1 , which might serve as promising candidates for applications in nano-electronics.