聚芴/金與聚咔唑衍生物/碳六十奈米複合材料之製備及其在高分子發光二極體與太陽能電池上之應用

Abstract

本論文合成三系列共軛高分子應用於高分子發光二極體及高分子太陽能電池。第一部份係合成主鏈含參苯基胺團基之聚芴共軛高分子，此高分子含有甲硫苯側基，金奈米粒子可以透過此團基與聚芴共軛高分子結合。研究結果顯示含有奈米金粒子之聚合物可以大幅降低高分子鏈之聚集，因此其量子效率可提昇50 %，而含金奈米粒子之聚芴製備成高分子發光二極體元件，其亮度為純聚芴元件之四倍，而其電激發光光譜之半高寬也變得比較窄。此結果證明導入金奈米粒子於聚芴共軛高分子中，可以大幅提高其電子之注入與傳輸，並且有效抑制聚芴高分子之氧化。本研究第二部份合成兩種含有機染料團基之聚咔唑（PCDCN和PCDTA），所合成之低能隙高分子，其能隙為1.5ev，而其吸收光譜非常寬，從300奈米延伸至700奈米。此二種聚合物分別與碳七十衍生物以1:4之重量比摻合，製備成有機太陽能電池元件。其中以PCDCN所製備之元件，能量轉換效率為2.31 %；而以PCDTA所製備之元件，其能量轉換效率則高達2.47 %。本研究的最後一部份則是探討聚合物與碳六十衍生物間產生之氫鍵作用力，對於摻合物形態學及元件效率之影響。此部份係設計合成含有吡啶側基之聚咔唑，吡啶團基可以和碳六十衍生物上之羧酸基形成氫鍵。而結果顯示含吡啶側基之聚咔唑在加入末端含羧酸基之碳六十衍生物後，其形成之薄膜於長時間加熱迴火後仍可以穩定保持其穩定之形態學；而其製作出之元件在經高溫迴火五小時之後，能量轉換效率仍能保持於原來之百分之七十五以上。

Three series of conjugated polymers were synthesized in this dissertation for the applications of PLED and Polymer Solar Cell. First, we synthesized poly{2,7-(9,9´-dioctylfluorene)-co-4-diphenylamino-4´-bipenylmethylsulfide}(PF-DBMS). Through in situ reduction of a gold precursor, we have tethered gold nanoparticles (Au NPs) to the side chains of this polymer through its ArSCH3 anchor groups. The presence of 1 wt% of the tethered Au NPs led to a reduction in the degree of aggregation of the polymer chains, resulting in a 50% increase in its quantum yield. The electroluminescence of a 1wt% Au/PF-DBMS device was almost four times higher in terms of its maximum brightness and its full-width-at-half-maximum emission peak was much narrower than that of a pure PF-DBMS device; the presence of a small amount of Au NPs significantly enhances the electron injection and transport and suppresses the photo-oxidation of PF-DBMS. In the second part of this study, we have synthesized and characterized two new carbazole-based conjugated polymers, PCDCN and PCDTA, incorporating two strong light-absorbing organic dyes. These polymers exhibit relatively low band gaps (ca. 1.5 eV) and broad absorption ranges (from 300 to 700 nm). We fabricated polymer solar cells incorporating these polymers as donors and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. At a blending ratio of 1:4, we obtained power conversion efficiencies, under simulated AM 1.5 (100 mW/cm2) conditions, of 2.31 and 2.47% for the PCDCN-based and PCDTA-based devices, respectively. Finally, we designed and synthesized two of conjugated polymers (P1 and P2) containing alternating electron-donating and electron-accepting units based on N-alkyl-2,7-carbazole- 4,7-di(thiophen-5-yl)-2,1,3-benzothiadiazole and 3-[2-(4-pyridyl)vinyl]thiophene units. The conjugated polymers containing various amount of 3-[2-(4-pyridyl)vinyl]thiophene unit which is used to form H-bonding with [6,6]-phenyl-C61-butyric acid (PCBA). As the H-bonding interaction introduced into the polymer thin film, the thermal stability of it is improved and the deterioration from the aggregation of PCBM after long time annealing is also suppressed. The PCE value of the device incorporating H-bonding interaction was kept at 75 % above of the original one after five-hour thermal annealing treatment (140 oC).