Star-shaped pi-conjugated oligomers and their applications in organic electronics and photonics.
Strategies for the design and construction of non-linear, 2D and 3D conjugated macromolecules are presented in this critical review. The materials, termed here as star-shaped structures, feature a core unit which may or may not provide conjugated links between arms that radiate like spokes from a central axle. The arms of the macromolecules consist of linear oligomers or irregular conjugated chains lacking a formal repeat unit. The cores range from simple atoms to single or fused aromatic units and can provide a high level of symmetry to the overall structure. The physical properties of the star-shaped materials can be markedly different to their simple, linear conjugated analogues. These differences are highlighted and we report on anomalies in absorption/emission characteristics, electronic energy levels, thermal properties and morphology of thin films. We provide numerous examples for the application of star-shaped conjugated macromolecules in organic semiconductor devices; a comparison of their device performance with those comprising analogous linear systems provides clear evidence that the star-shaped compounds are an important class of material in organic electronics. Moreover, these structures are monodisperse, well-defined, discrete molecules with 100% synthetic reproducibility, and possess high purity and excellent solubility in common organic solvents. They feature many of the attributes of plastic materials (good film-forming properties, thermal stability, flexibility) and are therefore extremely attractive alternatives to conjugated polymers (210 references).
WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, UK.
Alexander L
AL
Kanibolotsky
Igor F
IF
Perepichka
Peter J
PJ
Skabara