在應用於染料敏化太陽能電池(Dye-sensitized Solar Cells)的諸多染料中，釕錯合物因同時具有金屬-配位基電荷轉移(Metal-to-Ligand Charge Transfer)躍遷，以及配位基之間的電荷轉移(Ligand-to-Ligand Charge Transfer)等躍遷特性，其吸光範圍能涵蓋可見光甚至是部分近紅外光，而且釕錯合物的吸光波段、強度也可藉由配位基的分子設計進一步調整、強化，以利提高其敏化元件的光電流密度與光電轉換效率。本研究是以含有三聯吡啶(Terpyridine)固著配位基的Black dye (N749)為基礎，設計合成兩個新型多聯吡啶釕錯合物(代號為CYC-42Cl與CYC-43Cl)，其分子結構特色是透過連接己基噻吩(Hexylthiophene)的雙聯吡啶(Bipyridine)取代原有的兩個異硫氰酸(Isothiocyanate)單牙配位基，此外，也分別使用叔丁基噻吩(tert-Butylthiophene)和2-氯噻吩(2-Chlorothiophene)置換原先三聯吡啶固著配位基上的一個羧酸基，藉此比較、探討引入叔丁基和氯原子所產生的推拉電子效應、以及分子間作用力差異。在二甲基甲醯胺溶液中，CYC-42Cl和CYC-43Cl不僅展現了優異的吸光能力(其最低能量的吸收峰波長皆為542 nm，吸收係數則分別為19.9 × 103 M-1 cm-1與18.7 × 103 M-1 cm-1)，其前置軌域的位能也十分相近，儘管如此，在沒有使用任何共吸附劑的條件下，CYC-42Cl和CYC-43Cl敏化元件的光電轉換效率分別為5.40%與6.47%；導入共吸附劑進行初步優化後，兩者敏化元件的光電轉換效率則分別為7.89%與7.71%，這些結果顯示，在釕錯合物固著配位基上引入氯原子時，其產生的分子間作用力對元件特性之影響程度是比拉電子效應更加顯著，此發現也可望為新型多聯吡啶釕錯合物的分子設計提供新方向。;Among numerous photosensitizers applied in dye-sensitized solar cells (DSCs), ruthenium (Ru) complexes simultaneously exhibit metal-to-ligand charge transfer (MLCT) and ligand-to-ligand charge transfer (LLCT) transi-tions. These transition characteristics allow their absorption range to cover visible light and even extend into the near-infrared region. Moreover, their absorption bands and intensities can be further adjusted and enhanced through the molecular-engineering of the ligands, which can improve the short-circuit current density and power conversion efficiency (PCE) of the corresponding devices. This study is initiated from black dye (N749) con-taining one terpyridine anchoring ligand. We designed and synthesized two new polypyridyl Ru complexes (named CYC-42Cl and CYC-43Cl). The key feature of their molecular structures is that two isothiocyanate mono-dentate ligands on black dye were replaced by bis-hexylthiophene-substituted bipyridine. In addition, tert-butylthiophene and chloro-thiophene were introduced in the anchoring ligand to replace a carboxylic acid group for comparing the push-pull effects produced by tert-butyl group and chlo-rine atoms, as well as investigating the differences in intermolecular interac-tion. In DMF, CYC-42Cl and CYC-43Cl exhibit excellent light absorption capabilities (the lowest energy absorption peak wavelength is both at 542 nm, and the absorption coefficients are 19.9 × 103 M-1 cm-1 and 18.7 × 103 M-1 cm-1, respectively). Their frontier orbitals potentials are also very simi-lar. However, the corresponding devices (without any coadsorbent) show the PCE of 5.40% and 6.47%, respectively. After adding coadsorbents for pre-liminary optimization, the PCE of devices sensitized with the two sensitized devices are improved to 7.89% and 7.71%, respectively. These results demonstrate that when introducing chlorine in the anchoring ligand of Ru complexes, the impact of the induced intermolecular interaction on the prop-erties of the photosensitizers is more significant than the electron-withdrawing effect. This new finding also holds promise for providing new clues in the molecular design of new polypyridyl ruthenium complexes.
