ELECTRICAL IMPROVEMENT OF PEDOT : PSS BY INCORPORATION OF GRAPHENE AND SOLVENT DIPPING TREATMENT

In this research, the electrical conductivity of poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) ink was improved by adding graphene which is the excellent material in terms of electrical conductivity. Here, click reaction was conducted as a chemical functionalization for improving graphene dispersion in PEDOT:PSS. Click reaction was carried out under mild reaction condition with high yield. Graphene was synthesized via modified Hummer method following by reduction with hydrazine. A terminal alkyne modified graphene sheet was prepared by amidation, while the terminal azide modified PEDOT:PSS was synthesized. The alkyne and azide functional groups were coupled via click reaction using copper as catalyst. The results showed that the modified graphene was well dispersed in PEDOT:PSS composites in comparison with the unmodified graphene as a result of improved interaction but it tended to aggregate as loading increased. Furthermore, the electrical conductivities of modified PEDOT:PSS-graphene composites were higher than those of unmodified ones. However, the electrical conductivity was still not high as expected; the dipping method of dried PEDOT:PSS films was also studied. It was found that the electrical conductivity was significantly improved when the PEDOT:PSS film was dipped in low concentration of aqueous dimethyl sulfoxide solution. Moreover, the dipped film showed high transparency and low surface roughness without crinkles and white patches which might be found in case of the film dipped in pure water and pure dimethyl sulfoxide.