Optical properties and electronic structure of poly(1,4-bis(2-thienyl)-2,5-dialkoxy phenylene)

Abstract

Optical properties and electronic structure of a new fusible and soluble conducting polymer based on poly(p-phenylene), poly(1,4- bis(2-thienyl)-2,5-dialkoxy phenylene) (ROPBTP), are investigated. From the optical absorption edge, the band gap of ROPBTP has been evaluated to be about 2.3 eV. The electronic structure of ROPBTP is similar to that of poly(2,5-dialkoxy-p-phenylene vinylene) (ROPPV). Electrochromism from orange to blue is observed in ROPBTP upon electrochemical oxidation and strong yellowish-green emission as strong as that from ROPPV is observed in an electroluminescence device with Al/ROPBTP/ITO structure. The thermochromic behaviour of ROPBTP is a little different from that of poly(3-alkylthiophene) (PAT), which difference is discussed by taking differences in molecular structures into account.