太陽能電池是將光能轉換成電能的一種裝置，利用太陽能發電來做為電力的供應，是目前眾所矚目的研究，太陽能取之不盡、用之不竭的優勢使其在能源上扮演了重要的角色。第三代太陽能電池中的染料敏化太陽能電池 ( DSCs ) 因具有透光性、多色彩、可撓曲及成本低廉等優點，成為近年來科學家研究的重點之ㄧ。 DSCs 所用染料最主要的是以釕過渡金屬為中心的錯合物以及有機小分子，其中有機染料分子因具有材料設計較彈性且吸收係數高的優勢，備受重視。僅管如此，卻只有少數的有機染料分子能有效的吸收遠紅光(FR)及近紅外光(NIR)區的光。NIR染料光敏化劑應用在太陽能電池中的優勢，就是具有極高的吸收係數 (可高達10萬M-1cm-1以上)，且最大吸收波長位於遠紅光或近紅外光的波段。因此，本研究在染料分子結構中引入 Squaraine 片段為中心主體，採用Donor-Accepter的設計概念，利用 thiophene 單元及電洞傳輸能力佳的carbazole 片段做為 donor group，合成出不對稱型的染料 JYL-SQ1、JYL-SQ2 及 THL-SQ3。這三個 squaraine 染料光敏化劑之最大吸收波長分別為 568 nm、603 nm 和 612 nm，吸收係數為 85791 M-1 cm-1、68694 M-1 cm-1和 134151 M-1 cm-1，其中 JYL-SQ2 組裝成電池元件具有最好的光電轉換效率(2.59 %)，為以 N719 染料做為光敏劑之所組成元件效率 (4.40 %) 的60 %，預期以此設計概念來合成 squaraine 染料具有很好的發展潛力。 Solar energy is one of the most promising energy resources due to its cleanliness and abundance. Amongst the newly developed photovoltaic technologies to convert sunlight to electricity, Dye-sensitized solar cells (DSCs) have attracted significant attention as one of the low-cost alternatives for the realistic applications due to their impressive conversion efficiency. Numerous metal-free organic dyes with high molar extinction coefficients have been developed. Nevertheless, there are few dyes which can efficiently absorb the far-red and near-IR lights. In this thesis we synthesize a series of unsymmetrical squaraine photo-sensitizer: JYL-SQ1, JYL-SQ2, and THL-SQ3. These squaraine sensitizers contain a donor group (such as thiopene or carbazole), a conjugate moiety (squaraine) and an acceptor group (indoline with COOH). The carbazole-containing sensitizers show widely absorption bands and the absorption maximum (λmax) of THL-SQ3 is slightly red shifted to 612 nm compared to JYL-SQ1 and JYL-SQ2 (with an absorption maximum at 603 nm and 568 nm, respectively). Furthermore, the corresponding molar absorption coefficient (ε) of THL-SQ3 (134151 M-1 cm-1) is higher than those for JYL-SQ1 (85791 M-1 cm-1) and JYL-SQ2 (68694 M-1 cm-1). The overall conversion efficiency (η) for JYL-SQ2 was 2.59 %, which is 60 % of the N719 based device (4.40 %) fabricated at the same condition. The data reveal that such type of molecular design has great potential to prepare high efficiency sensitizers for dye sensitized solar cells.
