含雜環之新型窄能隙共軛高分子於有機光伏電池應用之合成與鑑定

Abstract

本論文研究方向為探討一系列包含窄能隙共軛高分子之合成與其在有機太陽能電池的應用，並以三大方向為研究主軸。第一個部份，包含了以烷基取代的茀(Flourene)單元與雜環bis-(2-aryl-2-cyanovinyl)-10-hexylphenothiazine衍生物之單體為高分子主鏈結構，成功的以Suzuki coupling聚合出12個新的高分子。第二，另一些新的雜環包含arylcyanovinyl與keto取代基的cyclopentadithiophene單體，也成功地以Suzuki coupling聚合出5個新的共軛高分子。最後一個部份，將另一些新型之bithiazole/thienyl基團的單體與cyclopentadithiophene單體做為研究的主題，共聚出六個共軛高分子。在鑑定方面，藉由1HNMR光譜圖上的積分值可輕易的鑑定出共軛高分子的主鏈結構是由上同的單體所建構。然而，利用紫外光-可見光光譜儀，這些共軛高分子顯示了從400至900 nm如此寬廣的吸收能帶，且其光學能隙大約在1.38-2.10 eV之間。而利用X光繞射圖譜（XRD）可以更進一步證明這些共軛高分子本身就具有高度的自我堆疊的效果。結果發現，在AM1.5G、100 mW/cm2的模擬太陽光下，將合成出之高分子與PCBM ([6,6]-phenyl C61-butyric acid methyl ester)混合(blend)為主動層材料，成功地以1:2w/w的混合比例得到一具有短路電流8.00 mA/cm2、開路電壓0.70 V、填充因子0.537及最高之光電轉換效率3.04%之有機太陽能電池。

First, novel twelve narrow-band-gap conjugated copolymers consisting of the comonomers alkyl-substituted fluorene and mono- and bis-(2-aryl-2-cyanovinyl)-10-hexylphenothiazine were copolymerized by a padallium-catalyzed Suzuki coupling reaction with two different feed ratios. The polymers showed broad optical absorption from 400 to 800 nm with optical band gaps at 1.55-2.10 eV. Second, other novel groups of five cyclopentadithiophene-based copolymers employing arylcyanovinyl and keto groups in different molar ratios were also synthesized successfully by palladium (0)-catalyzed Suzuki coupling reactions. Finally, six novel conjugated copolymers containing coplanar cyclopentadithiophene units (incorporated with bithiazole/thienyl-based monomers) were synthesized and developed for the applications of polymer solar cells (PSCs). For these cyclopentadithiophene-based copolymers, they showed broad optical absorption from 400 to 900 nm with optical band gaps at 1.38-1.94 eV. Powder X-ray diffraction (XRD) analyses suggested that these copolymers formed highly self-assembled π-π stackings. Under 100 mW/cm2 of AM 1.5 white-light illumination, as blended with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an electron acceptor in bulk heterojunction photovoltaic devices, narrow-band-gap polymers as electron donors showed significant photovoltaic performance which varied with the intramolecular donor-acceptor interaction and their mixing ratios to PCBM. The PSC device in the weight ratio of 1:2 with PCBM gave the best preliminary result with an overall power conversion efficiency (PCE) of 3.04%, an open-circuit voltage of 0.70 V, a short-circuit current of 8.00 mA/cm2, and a fill factor of 53.7%.