由於電子予體-輔助電子受體-電子受體型(D-A’-A；D = donor，A’ = auxiliary acceptor，A = anchoring acceptor)染料具有良好光捕捉效能 (light-harvesting efficiency)、較小的能階差 (bandgap)以及極佳的光穩定性 (photostability)，本論文研究開發出一系列以此形式為主的HJ系列新型非金屬系有機染料，染料之共軛鏈中包含以兩側連接具有長碳鏈己基之噻吩的四嗪或者噠嗪 (bis(n-hexylthienyl)tetrazine or bis(n-hexylthienyl)pyridazine) 主體架構，以及在主體一端分別以三苯胺 (triphenylamine)、具有乙基己基取代之咔唑 (9-(2-ethylhexyl)-9H-carbazole)、噻吩二苯胺 (N,N-diphenylthiophene-2-amine)或具有己氧基取代之三苯胺 (4-(hexyloxy)-N-(4-(hexyloxy)phenyl)-N-phenylaniline) 作為電子予體，並在另一端以氰乙酸 (2-cyanoacetic acid)作為吸附錨基 (anchor)之電子受體。以光物理及電化學的量測結果可得知，具有四嗪或噠嗪輔助電子受體之HJ系列染料的吸收光範圍在300至600 nm間，而莫耳消光係數 (molar extinction coefficient)可高達約60,000 M-1 cm-1；最高填滿分子軌域 (HOMO)與最低未填滿分子軌域 (LUMO)則是分別落在-5.89至-5.43 eV以及-3.54至-3.16 eV之間，說明染料分子具有適合的電子注入 (injection)與再生能力 (regeneration)。由DSSC元件在AM 1.5 G模擬太陽光源的條件下量測結果得知，HJ系列染料的光電轉換效率 (light-to-electricity conversion efficiency)分布範圍於0.35至6.25%之間，如此落差可歸因於染料分子間的嚴重堆疊 (aggregation)以及電子被束縛 (electron trapping)於拉電子能力 (electron-withdrawing)太強的四嗪結構，此結果亦可以理論計算之結果印證。加入共吸附劑 (co-adsorbent)優化後的元件，其光電轉換效率可提升至6.31%，高達標準N719電池的76%。;Sensitizers of D-A’-A type (D = donor; A’ = auxiliary acceptor; A = anchoring acceptor) have been widely investigated due to their good light-harvesting efficiency, low HOMO/LOMO gap, and excellent photostability. In this research, a series of new D-A’-A type sensitizers (HJ dyes) composed of a bis(n-hexylthienyl)tetrazine (TTz) or bis(n-hexylthienyl)pyridazine (TPz) core, an arylamine donor, such as triphenylamine, 9-(2-ethylhexyl)-9H-carbazole, N,N-diphenylthiophene-2-amine, and 4-(hexyloxy)-N- (4-(hexyloxy)phenyl)-N-phenylaniline as the electron donor entity and the 2-cyanoacetic acid as the acceptor as well as anchor have been synthesized for DSSC applications. These new dyes with tetrazine or pyridazine auxiliary acceptors have electronic absorption ranging from 300 to 600 nm, and the highest molar extinction coefficient reaching approximately 60,000 M-1cm-1. The HOMO (-5.89 to -5.43 eV) and LUMO (-3.54 to -3.16 eV) energy levels of the dyes calculated from the electrochemical and photophysical data assure favorable electron injection and regeneration. The light-to-electricity conversion efficiency of DSSC based on the HJ dyes is in a wide range of 0.35 to 6.25% under simulated AM 1.5 G illuminations. Low efficiencies of the cells can be attributed to the serious dye aggregation and the electron trapping effect, which is also supported by the theoretical calculation. Upon addition of CDCA as the co-adsorbent, the best performance has been slightly improved to 6.31%, which is of 76% of the N719-based standard DSSC.
