有機光敏化劑相較於一般Grätzel太陽能電池常用之釕金屬錯合物染料，有著無使用貴重金屬與高吸收係數之優點，並可經由多種有機結構的調變以增加光敏化劑的效能。一般有機小分子光敏化劑在設計上是在染料分子的一端接上具有推電子能力的取代基(如：含N、O的官能基)做為Donor，而在另一端接上具拉電子能力的取代基(如CN加上敏化劑所需具備的羧酸根)，稱之為Acceptor，在Donor與Acceptor中間置入可以傳遞電子的共軛結構(稱之為Spacer)，形成Donor-Spacer-Acceptor的結構。本研究是以具推電子能力的N-aryl Carbazole及Triphenylamine做為Donor，以雙噻吩環戊烷Cyclopentadithiophene (CPDT)做為Spacer，並在Donor與Spacer間分別引入了thiophene、bithiophene與octylthiophene來增加染料的共軛長度，所得光敏劑並組裝成染料敏化太陽能電池以測試光敏劑之結構與效能的關係，結果顯示以N-aryl Carbazole為Donor，bithiophene-CPDT 為Spacer之染料有最大的光電轉換效率 (1.78 %)，而影響有機染料之效能的因素很多，如吸收位置、HOMO與LUMO分佈的位置及分子中共軛片段的夾角，但與染料分子的吸收係數似乎沒有很大的關係。 The advantages of metal free sensitizers, compared to the Ru-based sensitizer in the Grätzel cell, are the high absorption coefficient and without using expensive metal. Furthermore, the structure of organic sensitizers can be widely modified to enhance the performance for solar cells. In general, the organic sensitizer contains a Donor group (such as Carbazole or Triphenylamine), a Spacer and Acceptor group (CN with COOH) to form so called Donor-Spacer-Acceptor type dyes. We synthesize a series organic dyes containing N-arylcarbazole or Triphenylamine as donor group and cyano arylic acid as a Acceptor, a low band gap CPDT moiety with thiophene, bithiophene, or octylthiophene, respectively as a Spacer. Dye-sensitize Solar Cells (DSCs) based on these dyes were fabricated and their performance was test to reveal the relationship between the structure of the dye and the performance of the DSC based on it. It was found that dye using N-aryl Carbazole as a Donor and CPDT-bithiophene as a Spacer has the highest conversion efficiency of 1.78%. Several parameters will affect the performance of dye for solar cell, such as ?max, distribution of HOMO and LUMO, and molecular dihedral angle. Nevertheless, it seems that the absorption coefficient of the dye did not have a significant effect on the conversion efficiency of the DSC based on it。
