可作為敏染太陽能電池之雙錨基咪唑光敏染料

Abstract

本篇論文開發了引入imidazole於電子予體與電子受體間之共軛鏈的光敏染料，並製成染敏型太陽能電池。利用carbazole或arylamine為電子予體，引入於imidazole之2號碳原子，並引入2-cyanoacetic acid於imidazole之4、5號碳原子，作為電子受體兼錨基。這樣的雙錨基分子設計可能有利於分子的光收成與增進光激發後分子注入電子於之TiO2能力。開發染料分子所涉及的重要有機反應包括Debus-Radziszewski imidazole synthesis、Stille Coupling與Knoevenagel condensation。新染料分子之物理特性並經UV-Vis.吸收光譜、微分脈衝伏安法，測量其光物理及電化學鑑定。這些染料分子在300−600 nm波段有高的分子吸收消光係數。由於明顯的分子堆疊，導致太陽能電池的效率只是中等。加入CDCA (chenodeoxycholic acid)為共吸附劑後效率可提升42–61%。最佳元件(加入50 mM CDCA)效率可達4.55%，為N719建構標準元件之61%。

Serious new organic dyes containing an imidazole entity in the conjugated spacer between the electron donor and electron acceptor have been synthesized for dye-sensitized solar cell (DSSC) applications. The carbazole or arylamine donor was incorporated at the C-2 of the imidazole entity, and the the two 2-cyanoacetic acid acceptors (as well as anchor) were incorporated at C-4 and C-5 of the imidazole entity, respectively. Molecules with two anchors may be beneficial to light-harvesting and electron injection from the photolytically excited dye to the TiO2. The key reactions involve in the preparation of the dyes include Debus-Radziszewski imidazole synthesis, StilleCoupling and Knoevenagel condensation. The physical properties of the new dyes were characterized by UV-Vis absorption spectra, cyclic voltammetry. The dyes exhibit optical absorption from 300−600 nm with high molar extinction coefficients. The conversion efficiencies of DSSCs fabricated from the dyes are moderate due to serious dye aggregation. Upon addition of CDCA co-adsorbents, the optimized cell efficiencies were improved by 42–61%. The best efficiency of the cell (with addition of 50 mM CDCA) was 4.55%, which reached 61% of N719-based DSSC fabricated and measured under similar condition.