合成含電子匱乏之單,雙錨基有機染料及其染料敏化太陽能電池之探討

MOLECULAR ENGINEERING OF MONO AND DI -ANCHORING METAL FREE ORGANIC SENSITIZERS CONTAINING ELECTRON DEFICIENT ENTITY FOR DYE SENSITIZED SOLAR CELLS (DSSCs)

徳沐露(Mulu Berhe Desta)

指導教授 ： 刁維光 ； 林建村

國立交通大學/理學院/永續化學科技國際研究生博士學位學程/博士(2018年)

摘要

全球人口的增長和能源需求的不斷上漲，加上環境問題以及不可再生石油資源的枯竭，促使研究人員尋求替代性的，環保的低碳可再生能源，如太陽能。從過去幾年來，由於更好的光捕獲（因此更高的光電流），與它們的單錨基同源物相比，雙錨基無金屬有機染料（即D-（π-A）2）吸引了巨大的潛力，以更好的結合和/或更高的染料加載量。
在本論文中，我們針對具有單/雙錨定基團的幾種有機染料的設計，合成和表徵。有機染料的合成基於我們的新型方法D‒A'‒π‒A用於單錨定和D‒ (π‒A)2用於雙錨定染料，其中A'指缺電子實體，D指到供體和A是指錨定基團（即氰乙酸）。
在我們的第一個項目中，我們研究苯並咪唑衍生的雙錨基化合物，我們製備了三種新的染料MD1‒MD3，與單錨基同系物和其他報導的染料相比，製備的DSSC的總體性能顯示出更好的效率，範圍為4.74‒6.69% 。由於這些染料顯示藍移吸收，因此選擇另一種有趣的缺電子實體吡嗪作為建構單元。在第二個項目中，我們開發可室內和室外使用DSSC之無非金屬系光敏染料。我們認為，在可見光範圍內達到〜650 nm的全色吸收染料可以覆蓋T5或白色LED光源的光譜。為了實現這一目標，我們著手開發D‒A'‒π‒A（D = 電子給體，A' = 輔助受體，π = π共軛橋，A = 電子受體/錨）型敏化劑。在D‒π‒A染料的共軛架橋中引入缺電子實體作為輔助受體有利於由於LUMO加深和改善敏化劑的光穩定性而使吸收光譜發生紅移。具有兩個雙（烷氧基）苯基取代基的新型D‒A'‒π‒A型（D = 電子給體，A' = 輔助受體，π = π共軛橋，A = 電子受體/錨）光敏染料噻吩並[ 4-b]吡嗪（TP）或苯並[3,4-b]吡嗪（BP）實體作為輔助受體已經合成用於染料敏化太陽能電池（DSSC）應用。在一個太陽照射下，由兩種BP染料和共吸附劑製備的DSSCs的效率分別為8.39%與9.03%。後者超過標準N719染料（8.87%）。在弱光照條件下，MD7的功率轉換效率分別為18.95% (300勒克斯照度)和27.17% (6000勒克斯照度)。

關鍵字

吡嗪 ； 電子匱乏 ； 有機染料 ； 染料敏化太陽能電池 ； 低照度

並列摘要

The growth of global population and rising energy demand, coupled with environmental concerns, as well as the depletion of non-renewable petroleum resources have motivated researchers to seek alternative, environmentally friendly low-carbon renewable energy sources, such as solar energy. From the past few years, di-anchoring metal-free organic dyes (i.e. D‒ (π‒A)2) had attracted an immense potential due to better light harvesting (and therefore higher photocurrent) compared with their mono-anchoring congeners, due to better conjugation and/or higher dye loading.
In this thesis, we have targeted the design, synthesis and characterization of several organic dyes bearing mono/di-anchoring groups. The synthesis of the organic dyes was based on our novel approach D‒A'‒π‒A for mono-anchoring and D‒ (π‒A)2 for di-anchoring dyes, where A' refers to electron deficient entities, D refers to Donor and A refers to electron acceptor/anchoring group (i. e. cyanoacetic acid). In our first project we started working on benzimidazole based di-anchoring compounds, we prepared three new dyes MD1–MD3, the overall performance of the DSSCs prepared showed better efficiencies ranging between 4.74‒6.69%, compared to their mono-anchor congeners and other reported dyes. Since these dyes shows a blue shifted absorption, another interesting electron deficient entity pyrazine was chosen as a building block. In the second project, we intended to develop metal-free sensitizers for both indoor and outdoor DSSCs. We figured that dyes with panchromatic absorption in the visible region up to ~650 nm could cover the spectrum of T5 or white LED light source. In order to achieve this goal, we set out to develop D−A′−π−A type sensitizers. Incorporation of an electron deficient entity as auxiliary acceptor in the conjugated spacer of D−π−A dyes is beneficial for red shifting the absorption spectra due to deepened LUMO and improving the photostability of sensitizers. New D−A′−π−A type sensitizers with two bis(alkoxy)phenyl substituents incorporated thieno[3,4-b]pyrazines (TP) or benzo[3,4-b]pyrazine (BP) entity as the auxiliary acceptor have been synthesized for dye-sensitized solar cells (DSSCs) application. Under 1 sun illumination, the DSSCs fabricated from the two BP dyes with co-adsorbent have efficiencies of 8.39% and 9.03%, respectively. The latter surpasses that of the standard N719 dye (8.87%). Under dim light condition MD7 exhibited a power conversion efficiency of 18.95% and 27.17% under 300 lux and 6000 lux irradiance, respectively.

並列關鍵字

Pyrazines ； Electron deficient entities ； Metal-free sensitizers ； Dye-Sensitized Solar Cells ； Dim-light

參考文獻

[1] Nazeeruddin, Md. K.; Baranoff, E.; Grätzel, M. Dye-Sensitized Solar Cells: A Brief Overview. Solar Energy 2011, 85, 1172.

[2] International Energy Agency, World Energy Outlook 2017, www.iea.org.

[3] Grätzel, M. Photo-electrochemical Cells. Nature 2001, 414, 338.

[4] Becquerel, A. E. Principles and Applications of Dye Sensitized Nanocrystalline Solar Cells. (dsc). C. R. Acad. Sci. Paris 1839, 9, 561.

[5] Green, M. A.; Emery, K.; Hishikawa, Y.; Warta, W.; Dunlop, E. D. Prog. Photovolt: Solar Cell Efficiency Tables (Version 38). Res. Appl. 2011, 19, 565.