Preparation and Photocurrent Properties of Tin Dioxide Electrode Modified by Polyimide Lagmuir-Blodgett Films Possessing Tetraphenylporphyrin Unit
| Autor: | Masa-aki Kakimoto, Yoshio Imai, Atsushi Morikawa, Yasunari Nishikata, Katsuhiko Nishiyama, Masamichi Fujihara |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | Polymer Journal. 22:593-600 |
| ISSN: | 1349-0540 0032-3896 |
| DOI: | 10.1295/polymj.22.593 |
| Popis: | Polyimide Langmuir-Blodgett (LB) film containing tetraphenylporphyrin (TPP) unit was newly prepared on the surface of tin dioxide electrode by “Precursor method” (Electrode I), and the generation of photocurrent was measured by the wet system. The photocurrent spectrum obtained was very similar in shape to the absorption spectrum of the LB film. The quantum efficiency of the electrode modified by one layer of the polyimide LB film was 0.178, and the values decreased with increasing the number of layers. The long term stability of the photocurrent of Electrode I was compared with that of the electrode possessing the monomeric TPP LB film prepared from a 1:1 mixture of monoamino-TPP and stearic acid (Electrode II). These two electrodes were stable under the irradiation of monochromatic light of 430 nm, while in the case of the direct irradiation of the xenon lamp, Electrode I kept the same level of the initial photocurrent for a long time, but Electrode II decreased to 50% within one hour. The absorption spectra indicated that both LB films did not come off from the surface of the electrodes during the photocurrent measurements. The decrease of the photocurrent of Electrode II was explained by the hydrophobicity of the surface of the LB film possessing the long alkyl chain and by the diffusing effect of the reducing agent in the electrolyte solution. |
| Databáze: | OpenAIRE |
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