摘要
染料敏化太陽能電池是目前最受矚目的有機太陽能電池元件，通常是以含有金屬原子的有機化合物做為染料。然而中心金屬價格較高且具高污染性，於是純有機的染料敏化太陽能電池成為了另一種低汙染且低成本的選項。本實驗室在先前的研究中發現使用含有正丁硫烷取代基之聚噻吩做為染料的染料敏化太陽能電池，其光電轉換效率最高可達1.41 %。相較於含有正己基取代基之聚噻吩，其應用在有機染料敏化太陽能電池上時因為在TiO2上的吸附效果很差，造成效率不高。 本論文接續先前本實驗室何明記碩士的研究，進一步將噻吩的3號位取代為硫酚基(phenylthio)與2-硫基吡啶(2-pyridinylthio)，因為透過理論計算發現將聚噻吩接上具有拉電子性的側鏈取代基時，當其被激發至激發態時，主鏈上的電子會轉移至側鏈上。而聚噻吩主鏈本身具有良好的電洞傳輸性質，此兩種電子特性結合之下，十分適合應用在太陽能電池上做為吸光材料。將接上取代基的噻吩單體以GRIM法和McCullough分別聚合成具高度位向選擇性的聚噻吩，但以GRIM法聚合時的單體分別以2,5號位雙邊溴化以及2號位為溴、五號位為碘的單體進行聚合，並比較兩種單體的聚合結果。經由製程上的調整，聚合的產率最高可達約60 %，分子量則介於1000~2500之間。接著將所得的聚噻吩製備成有機染料敏化太陽能電池進行效率的量測，其中poly[(3-phenylthio)thiophene]最高效率可達1.19 %，而poly[3-(2-pyridinylthio)thiophene]的最高效率為0.25 %。
關鍵字
聚噻吩並列摘要
In the last decade, dye-sensitized solar cells (DSSCs), based on organic compounds containing metal atoms as a dye material, have become more popular due to their low-cost production and high efficiency. However, the cost and environmental pollution associated with the metal-containing DSSCs are found to be very high, which demand researchers to look for an alternative source of dye, such as pure organic DSSC dyes. Among various dye materials, polythiophene derivatives are of great interest due to their unique combination of original electronic properties, environment stability, and structure versatility. Recently, our lab have made a DSSC containing polythiophene with butylthio substuient as a dye material. The photoelectric conversion efficiency of the DSSC was found to be up to 1.41%, which is much higher than the photo-electric efficiency of the device made up of poly(3-hexylthiophene) as the dye. The very low efficiency of poly(3-hexylthiophene) containing device could be due to the poor adsorption nature of the dye on TiO2 material. In this work, the synthetic methods for two new polymers, i.e., poly[3-(phenylthio)thiophene] and poly[3-(2-pyridinylthio)thiophene] were developed following the previous work done in our laboratory by Mr. Ming Kee Ho. We found through theoretical calculations that polythiophenes with electron withdrawing substituents at 3-position may provide an efficient way to transfer electrons from the main chain to their side chains during their photo-oxidation. While the polythiophene main chain itself holds a very good hole transporting properties and electrical conductivity. Thus, the combination of the polythiophene main chain and the electron withdrawing side chain substituent should render the dye with high DSSC efficiency. The in-house prepared monomers of 2,5-dibromo and 2-bromo derivatives of 3-(phenylthio)thiophene and 3-(2-pyridinylthio)thiophene were polymerized by GRIM and McCullough method, respectively, to give rise to regioregular polythiophenes. Both 2,5-dibromo-3-(arylthio)thiophene and 2-bromo-5-iodo-3-(aryl- thio)thiophene monomers were synthesized and polymerized by GRIM method, and their polymerizations results, based on the reactivity difference, were compared. The optimal yield was found to be 60% through the adjustment of process, and the molecular weight of the polymers were found to be between 1000 to 2500 by gel permeation chromatography (GPC) using polystyrene standards in THF eluant. DSSC devices have been prepared by using these polythiophene polymers as dye and efficiency measurements were performed for their corresponding devices. The devices have shown a maximum efficiency of up to 1.19% and 0.25% respectively, for poly[3-(phenylthio)thiophene] and poly[3-(2-pyridinylthio)thiophene].
並列關鍵字
polythiophene參考文獻
延伸閱讀
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