高分子膠態電解質混成碳材於染敏太陽能電池應用

Abstract

本論文分為兩大部分，第一部份是合成新型高分子型分散劑POE-segmented imide (POEM)，經由傅立葉轉換紅外線光譜儀(Fourier transform infrared spectroscopy, FTIR)證實具有亞醯胺及胺官能基。此分散劑可分散碳黑、奈米碳管、石墨烯等碳材，並且以穿透式電子顯微鏡(Transmission electron microscopy, TEM)和可見光紫外光分光光譜儀(UV-VIS Spectophotometer)佐證其分散性。 第二部分是合成高分子彈性體Poly(oxyethylene)-segmented amide-imide (POE-PAI)，其結構包含聚氧乙烯主鏈、醯胺、亞醯胺和分子間醯胺鍵等官能基，此彈性體能夠吸收電解液形成膠態電解質並應用於半固態染料敏化太陽能電池(Quasi-solid DSSC)中，吾人發現其吸取之電解液的量可占整體膠態電解液達80%以上，其光電轉換效率可達7.32%。吾人並進一步將以POEM分散過後的三種碳材進一步添加於POE-PAI彈性體中。由於碳材的優良導電性，電解液中的氧化還原對能夠更快速的傳遞，此結果能夠以彈性體的導離度(Ionic conductivity)和電化學交流阻抗分析(Electrochemical impedance spectra, EIS)佐證，以石墨烯改質過後的POE-PAI彈性體其效率可上升到7.96%，優於未改質前的彈性體。吾人更進一步以掃描式電子顯微鏡(Scanning electron microscopy, SEM)分析其表面特性，發現浸泡過電解液的彈性體表面會產生奈米等級通道，此通道能提供離子對傳遞。此外，隨著碳材添加的量增加，其表面型態也會隨之改變。

Different dimensional carbon materials, including multi-walled carbon nanotubes (MWCNT, one dimensional (1D)), graphene (two dimensional (2D)), and carbon black (zero dimensional (0D)), could be successively dispersed by an excellent home-made dispersant, namely poly(oxyethylene)-segmented imide (POE-segmented imide, POEM). The dispersibilities of the carbon materials in POEM were verified by UV-vis spectroscopy and transmission electron microscopy (TEM). The carbon materials (with the POEM) were then incorporated in an elastomer of poly(oxyethylene)-segmented amide-imide (POE-PAI), which was synthesized by the polymerization of poly(oxyethylene)-segmented diamine and 4,4-oxydiphthalic anhydride (ODPA). The carbon-incorporated polymer gels were used as quasi-solid-state electrolytes for dye-sensitized solar cells (DSSCs). The chemical structure of POE-PAI was characterized by Fourier transform infrared spectroscopy (FTIR). The DSSCs with graphene and MWCNT exhibited much higher power conversion efficiencies (η, 7.96% and 7.90%, respectively), compared to that of the DSSC with pristine POE-PAI as the polymer gel electrolyte (PGE, 7.32%); these enhanced η’s can be attributed to the higher ionic conductivities of the electrolytes with graphene and carbon nanotubes. Electrochemical impedance spectra and conductivity data are used to support these photovoltaic parameters. Furthermore, morphologies of the elastomers of these polymer gel electrolytes are found to play important roles in deciding the η’s of the pertinent DSSCs; these morphologies are examined through scanning electron microscope (SEM) images. The best power conversion efficiency (7.96%) obtained in this research is much better than most of the η’s obtained hitherto for quasi-solid state DSSCs.