Doping effects of photochromic dye on electrical and optical properties of conducting polymers and novel photomemory phenomena

Summary form only given. Electrical and optical properties of conducting polymers which contain a photochromic dye as a dopant have been studied. Photoluminescence spectra of soluble conducting polymers, poly(3 alkylthiophene) and poly(9,9-dialkylfluorene), were suppressed by doping of a photochromic dye, cis-1,2-dicyano-bis(2,4,5-trimethyl-3-thienyl)ethene. X-ray diffraction measurements showed good solubility of the photochromic dye in these soluble conducting polymer matrix. Electrical conductivity of these dye-doped conducting polymers showed no marked increase, while photoconductivity was enhanced in the case of poly(3-alkylthiophene) by the dye-doping. Photoconductivity of these dye-doped conducting polymers were suppressed by irradiation of UV-light which induces the photoisomerization reaction of the doped dye. The change in the photoconductivity showed photomemory effect. These doping effect of the photochromic dye on the properties of conducting polymers have been explained by the terms of changes in HOMO and LUMO states of the dye upon photoisornerization and in probability of photoinduced charge-transfer between the conducting polymers and the dye.