A robust low band gap processable n-type conducting polymer based on poly(isothianaphthene)

The novel macromolecule, poly(benzo[c]thiophene-N-2-ethylhexy-4,5-dicarboxy lic imide) (EHI-PITN), has been designed and synthesized. The polymer has a well-defined structure which was characterized by FTIR, H-1 NMR and C-13 N MR spectroscopies, and elemental analysis. TGA analysis indicates that the polymer has good thermal stability with an onset decomposition temperature of about 328 degreesC (N-2 atmosphere). The T-g of the polymer is about 256 degreesC. The optical properties of the conjugated polymer led to the conc lusion that the band gap of EHI-PITN is ca. 1.24 eV, which is comparable wi th the parent PITN and its derivatives. The data are also supported by the value obtained from cyclic voltammetry. The electrochemically determined HO MO energy is 4.88 eV, and the LUMO energy is 3.59 eV. These values are comp arable with those of the work functions of ITO and Mg/Ag, suggesting that E HI-PITN should find many organic electronic device applications.