Photocurrent generation of diarylethene polymers

The combination of photochromism and electrical properties in diarylethene (DA) polymers were investigated. Photoswitching function could be introduced into a polymer by incorporating 2,3-bis(2-methylbenzo[b]thiophene-3-yl) hexafluorocyclopentene (BTF) unit plus p-phenylene vinylene (PPV) unit alternatively. The photochromic film of BTF-PPV polymer become dark colored upon exposure to a UV light because π-conjugation delocalizes between the π-conjugative groups and the new absorption band centered at 570 nm was observed from the colored film. In dark the photochromic electrode coated with BTF-PPV copolymer did not show current generation. Upon exposure to UV, large incident photon-to-current generation was observed with the quinone/hydroquinone carrier couple under a bias potential of 165 mV (vs. Ag/AgCl). By optical modulation, a reversible photocurrent generation was observed from the photochromic electrode. On the otherhands, DA polymers derived from 2,3-bis(2-methyl-3-thienyl)hexafluorocyclopentene (TF) and PPV showed no photocurrent generation, indicating photodecomposition of the closed isomer.