NOVEL ELECTRICAL AND OPTICAL-PROPERTIES OF POLY(3-ALKYLTHIOPHENE) AS FUNCTION OF ALKYL CHAIN-LENGTH AND THEIR FUNCTIONAL APPLICATIONS

Electrical (conductivity, mobility), optical (absorption, luminescence ) and magnetic (ESR) properties of poly(3-alkylthiophene) were strongl y dependent on alkyl chain length, temperature and ambient conditions. These results can be explained by taking fluctuation of electronic ba nd scheme and inter-chain interaction influenced by dimensionality and co-planarity of conjugated main chain which are dependent on the alky l chain length and its conformation. Properties of mixture of poly(3-a lkylthiophene)s with different alkyl chain length were also discussed. Doping characteristics of poly(3-alkylthiophene) dependent on alkyl c hain length were discussed in terms of location of dopants in the poly mer, modification of crystal structure and polymer-dopant interaction. Especially, unique doping effect of C60 in poly(3-alkylthiophene) was also observed. As example of ambient effect on properties of poly(3-a lkylthiophene), characteristics of poly(3-alkylthiophene) in solvent a nd behavior in poly(3-alkylthiophene) gel were studied and discussed i n terms of interactions of solvent molecule with both polymer main cha in and alkyl side chain. Various applications of these unique characte ristics of poly(3-alkylthiophene) were proposed such as functional ele ctronic element (diodes, FET etc.), EL (electroluminescent diode), opt ical memory and functional gel elements (bimorph, actuator, etc.). The ir characteristics can also be controlled by the alkyl chain and expla ined in terms of unique electronic band scheme of poly(3-alkylthiophen e) dynamically dependent on alkyl chain length and ambient conditions.