| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 96 === The first step of this research was to fabricate poly(butyl acrylate) (PBA), poly (butyl acrylatet-co-acrylic acid) (P (BA-co-AA)) and poly (butyl acrylatet-co-maleic anhydride) (P(BA-co-ma)) latices by soap-free emulsion polymerization, and to fabricate their Montmorillonite (MMT) composite and multi-wall carbon nanotube (MWCNT) composite latices by using the same method. TEM, NMR, TGA and DSC were employed to investigate their morphology, chemical structures and thermal properties. After manufacturing the above latices, they were used to gel the LiI / I2 / TBP electrolyte systems in liquid propionitrile for preparation of dye-sensitized solar cells (DSSCs). Then, we investigated the effects of gel-type electrolytes on the performance of DSSCs in order to find suitable gelatinizing materials for higher performance and longer durability.
The conductivity of gel-type electrolytes could be estimated by using electrochemical impedance spectroscopy (EIS). The results showed that P(BA-co-AA) and P(BA-co-ma) gel-type electrolyte system had higher conductivity and ionic diffusion rate than PBA gel-type electrolyte system. In terms of the performances of devices, the best photon-to electron power conversion efficiency of PBA-gelled electrolyte system was 5.46% and that of P(BA-co-AA) and P (BA-co-ma) gelled electrolyte system was 7.88%. The higher efficiency of DSSCs with P(BA-co-AA) and P(BA-co-ma) gelled electrolyte system might be due to the higher dipole moment of gelatinizing polymers. Compared to the copolymer-gelled electrolytes, their MMT and MWCNT composite-gelled electrolytes had better power efficiency and higher open-circuit photovoltage.
In the durability test of the gel-type DSSCs, we found that the DSSCs with MMT/P(BA-co-ma) and MWCNT/P(BA-co-ma)-gelled electrolyte systems were able to remain 60% of the-first-day efficiency after thirty day test, and that with P(BA-co-ma)-gelled electrolyte system had efficiency drop to nil after eight day test. Apparently, incorporation of MMT or MWCNT to the copolymer-gelled electrolytes was able to prolong the survice life of DSSCs.
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