光敏化染料為染料敏化太陽能電池(Dye-sensitized Solar Cells (DSCs))的核心組成，亦為影響元件光電轉換效能與穩定性之重要關鍵；在眾多光敏化劑中，釕錯合物染料的MLCT (Metal-to-Ligand Charge Transfer)特性具有可使其敏化之元件有效吸收可見光與部份近紅外光等優點，有機會更進一步提高元件的光電流密度與光電轉換效率，因此本研究選擇以含有三吡啶(Terpyridine)固著配位基Black dye (N749)為基礎，設計合成出CYC-36 與 CYC-41兩個新型釕錯合物染料，其設計概念主要是在該固著配位基的吡啶4號位上分別以Pyrrole和首次應用在太陽能領域的Thieno[3,2-b]pyrrole單元取代原先的羧酸基，希望可藉此提高釕錯合物光敏化染料的吸光能力與元件效能。其中CYC-41的MLCT最大吸收波長(max)不僅可紅位移至615 nm (優於Black dye的599 nm)，吸收係數(8800 M-1 cm-1)亦優於Black dye (7500 M-1 cm-1)；搭配碘電解質時，元件的IPCE結果顯示兩新型染料相較於Black dye確實可有效提高電池在波長400到500 nm以及800到900 nm的轉換效能；在TiO2光電極厚度為45 µm與AM 1.5G模擬太陽光照射條件下，CYC-36所敏化之電池元件短路電流密度(Jsc)達17.34 mA cm-2 (優於Black dye的17.13 mA cm-2)，元件光電轉換效率為8.00% (相同條件下Black dye元件為8.93%)，另一方面，CYC-41在搭配TiO2光電極厚度為25 µm條件下，所敏化之電池元件亦較Black dye有較高的Jsc (17.62 mA cm-2 vs. 17.54 mA cm-2)，整體效能達7.82% (相同條件下Black dye元件為8.88%)。除合成兩新型釕錯合物染料外，本研究亦系統性地比較上述三個染料與先前本實驗室開發之CYC-37和CYC-39的光物理與電化學性質以及元件特性，以期能為後續設計高效率釕錯合物染料提供更明確的指引。;In dye-sensitized solar cells (DSCs), photosensitizer is the most important component affecting significantly power conversion efficiency (PCE) and stability of the devices. Among numerous photosensitizers, ruthenium (Ru) complexes sensitizers are very promising to enhance further the performance of devices, due to their metal–ligand charge transfer (MLCT) transition that extends into the red and near-infrared region. In this research, we designed and synthesized two new ruthenium complexes, coded CYC-36 and CYC-41, respectively. Our designing concept is based on Black dye (N749) which contains a terpyridine anchoring ligand. We replaced one carboxyl group at the fourth position of terpyridine ligand with pyrrole and thieno[3,2‑b]pyrrole, respectively. The maximum absorption wavelength (max) of CYC-41 is 615 nm red-shifted over 15 nm than that of Black dye. The molar absorption coefficient of CYC-41 (8800 M-1 cm-1) is also higher than of Black dye (7500 M-1 cm-1). IPCE results show the devices sensitized with CYC-36 and CYC-41 in conjunction with an iodide-based electrolyte can convert more blue and red light photons into electricity than that of Black dye. Moreover, when the thickness of TiO2 is fune-tuned to 45 µm and 25 µm, the Jsc of devices based on CYC-36 and CYC-41 reaches 17.34 mA cm-2 and 17.64 mA cm-2, yielding respectively the PCE of 8.00% and 7.82%. Under the same conditions, the performance of Black dye-based cell is 8.93% and 8.88%, respectively. In addition to the design of two new dyes, we compared systematically the properties and the device characteristics for the three dyes as well as CYC-37 and CYC-39 we developed previously to provide more clues of designing highly efficient ruthenium photosensitizers.
