Design of Organic Electrochromic Device

• Main Authors: Chao-tsun Chen, 陳兆村
• Other Authors: Wei-Li Yuan
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/35025448407983100275

碩士 === 逢甲大學 === 化學工程學所 === 94 === From the research and application, organic electrochromic materials have one advantage of multiple changes in color to make up for the single color of inorganic ones. Bipyridinium or the viologen family such as methyl viologen (MV) and heptyl viologen (HV) are the most popular electrochromic materials since their first report in 1973. The thesis focuses on the redox reactions and coloration behavior of HV, characterized by electrochemical and chemical methods; finding out the optimal range of applied voltage; comparing the aging degrees after life test of the electrochromic device (ECD) prepared at different HV concentrations; and observing the state changes of HV. From the results of cyclic voltammetry and UV-VIS spectra, the applied voltage should be set close to or slightly over the peak of the first reduction but avoid the appearance of the second reduction peak. As for an ECD on ITO with HV at 0.01 M, the decay of surface current density, after 20,000 coloration cycles, was 15.6% and the lowest; the optical density (ΔOD) was 0.43 and good for being used in ECD. As to an ECD on flexible ITO with HV at 0.01 M, the decay of surface current density, after 20,000 coloration cycles, was 2.5% more than that of the 0.02 M sample; ΔOD became 0.55, about 0.02 higher than that of the latter; the change in ΔOD was 16.4%. In comparison, the 0.01 M sample is better for being used in ECD. From observation by chemical titration of the three oxidation states of HV, as HV0 was formed, an oxidant was added to make it change back to HV2+. Results showed that the reversibility was not good and only 13%, indicating the formation of irreversible products such dimmers, which is related to the aging of the ECD and is for future study.