Novel Macromolecular Materials for Electronic and Optical Applications
Final rept. 1 Nov 95-31 Oct 97
CLARK ATLANTA UNIV GA DEPT OF CHEMISTRY
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A series of thiophene containing polyarylene ethynylenes have been synthesized and their molecular structures and PL properties have been characterized. A convenient synthetic route has been developed to prepare bis3-alkylthienylethyne 5 in high yield. Various attempts have been made to use 5 as an essential building block for developing novel polyarylene ethynylene materials. Regioregular poly3-hexyl-2,5- thienylene ethynylenes P3HTE have been synthesized in order to compare the steric interaction in the corresponding polymers. A systematic study has been carried out to evaluate the regioregularity effect of the polymer structure on the PL properties. P3HTE of a head-to-tail chain sequence 12 showed stronger PL intensity than the corresponding polymer with a head-to-head chain sequence 10, although they exhibit the essentially same absorbance. The quantum efficiency of P3HTEs were found to increase sharply with the conjugation length of the molecules when the chain length is shorter than the tetramer. Further extending the conjugation length beyond the tetramer appeared to shift the fluorescence emission band to a longer wavelength, but to have little effect on the quantum efficiency of teh molecule. Several alternating copolymers, polyP-PHENYLENE ETHYNYLENE-ALT-2,5-THIENYLENE ETHYNYLENEs PPETEs, have also been synthesized by using a Reck-type coupling reaction under mild conditions. PPETEs produced under the mild conditions exhibit longer conjugation length ca. 10 nm in UV-vis absorption max than the same polymers synthesized at high temperature. Synthesis of copolymer PPETE successfully combines both good solubility and processibility of PTE and high luminescence of PPE into a single polymer chain, making the material attractive for device applications.
- Polymer Chemistry
- Electrooptical and Optoelectronic Devices