| 摘要: | 染料敏化太陽能電池(Dye-sensitized solar cells，DSCs)中，染料分子負責吸收光子進而產生光電流，是影響元件光電轉換效率的重要因素，若以具有光致變色特性的分子作為染料將可能強化其應用範疇，但至今僅有全有機光致變色染料應用於DSCs的研究成果，因此本研究的分子設計是在2,2′-聯吡啶上分別連接單/雙取代3H-萘並吡喃基團的兩種新型光致變色配位基(L66和L68)，並將其配位至釕金屬合成出錯合物染料CYC-66和CYC-68。實驗上嘗試兩種合成方法，分別是將中間產物Ru(dcbpy)2Cl2導入AgNO3協助置換氯離子配位基後與L66/L68進行配位，以及先合成CYC-66 ester和CYC-68 ester後，再嘗試以不同水解路徑合成CYC-66和CYC-68。從水解前後的1H-NMR光譜圖可得知，溫和的水解條件是合成CYC-66和CYC-68的重要關鍵，並且使用有機鹼(40當量的NEt3)水解後的產物相較於使用無機鹼(45當量的Na2CO3)水解產物在d6-DMSO中具有更好的穩定性。CYC-66、CYC-68與本實驗室王道融學長合成之連接兩個3H-萘並吡喃單元的CYC-64具有相近的吸收波段(均落在約295–550 nm的範圍內)，顯示這些錯合物在紫外至可見光區域的吸光特性相似，惟於325–375 nm因2,2′-聯吡啶和3H-萘並吡喃的π → π*躍遷產生的吸收肩峰略有不同。此外，CYC-68和CYC-64亦表現出相近的吸收係數，皆約為CYC-66的1.2倍。在元件表現方面，無論是否添加共吸附劑，三種染料敏化元件的JSC值皆隨照射時間增加而出現活化現象，其中未添加共吸附劑的CYC-68敏化元件變化最顯著(由3.29 mA·cm-2提高至4.63 mA·cm-2)。照射AM 1.5G模擬太陽光超過1000秒後，三者的JSC值相近：CYC-64 / CYC-64+BPHA為4.49 / 6.09 mA·cm-2，CYC-66 / CYC-66+BPHA為4.29 / 6.20 mA·cm-2，CYC-68 / CYC-68+BPHA為4.63 / 5.94 mA·cm-2。實驗結果顯示，單取代3H-Naphthopyran的CYC-66因分子大小適中，吸附上TiO2後可形成更緊密的排列，因此提高其敏化元件的光捕獲效率。最終，添加5 mM BPHA後，CYC-64、CYC-66與CYC-68敏化元件的光電轉換效率分別達到2.37%、2.42%與2.32%。;In dye-sensitized solar cells (DSCs), dye molecules are responsible for absorbing light energy and generating photocurrent, making them a crucial factor influencing the photovoltaic conversion efficiency of the device. The use of photochromic molecules as dyes can enhance their application scope. However, to date, only fully organic photochromic dyes have been explored in DSC research. Therefore, this study focuses on the molecular design of two novel photochromic ligands, L66 and L68, which feature mono- and bis-3H-naphthopyran groups attached to a bipyridine core. These ligands were subsequently coordinated to ruthenium, forming the corresponding dye complexes, CYC-66 and CYC-68. Two synthetic approaches were attempted: one involved ligand exchange, facilitated by AgNO3, to remove chloride ions, thereby enabling the coordination of L66 or L68 to the ruthenium center; the other involved the synthesis of the ester derivatives, CYC-66 ester and CYC-68 ester, followed by different hydrolysis methods to obtain the target compounds. The 1H-NMR spectra measured before and after hydrolysis revealed that mild hydrolysis conditions were crucial for obtaining CYC-66 and CYC-68. Moreover, using an organic base (40 equivalents of NEt3) resulted in more excellent solution stability than using an inorganic base (45 equivalents of Na2CO3). CYC-66 and CYC-68, along with CYC-64 (which also contains two 3H-naphthopyran units), exhibited similar absorption bands within the range of approximately 295–550 nm, indicating comparable absorption properties in the ultraviolet-visible region. However, in the 325–375 nm range, slight differences were observed in the absorption shoulder peaks due to the π → π* transitions of the bipyridine and 3H-naphthopyran moieties. Additionally, CYC-68 and CYC-64 showed similar molar absorption coefficients, both approximately 1.2 times higher than that of CYC-66. Regarding device performance, the JSC values of all three dye-sensitized devices increased over time under illumination, exhibiting a photoactivation phenomenon regardless of the presence of a co-adsorbent. Among them, the CYC-68 sensitized devices (without BPHA) showed the most significant change, with JSC increasing from 3.29 mA·cm-2 to 4.63 mA·cm-2. After more than 1000 seconds of AM 1.5G illumination, the JSC values of the three devices became comparable: CYC-64 / CYC-64+BPHA at 4.49 / 6.09 mA·cm-2, CYC-66 / CYC-66+BPHA at 4.29 / 6.20 mA·cm-2, and CYC-68 / CYC-68+BPHA at 4.63 / 5.94 mA·cm-2. These data suggest that the mono-substituted 3H-Naphthopyran structure of CYC-66, due to its more suitable molecular size, enables a more compact arrangement upon adsorption onto TiO2, thereby enhancing light-harvesting efficiency. Consequently, after adding 5 mM BPHA, the power conversion efficiencies of the CYC-64, CYC-66, and CYC-68 sensitized devices reached power conversion efficiency (PCE) of 2.37%, 2.42%, and 2.32%, respectively. |
