Thermal Conversion of Precursor Soluble Polymer to Insoluble Low Bandgap Conjugated Polymers Containing Isothianaphthene Dimer Subunits
Thermal Conversion of Precursor Soluble Polymer to Insoluble Low Bandgap Conjugated Polymers Containing Isothianaphthene Dimer Subunits
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前体可溶性聚合物热转化为含有异硫茚二聚体亚基的不溶性低带隙共轭聚合物
DOI：
10.1021/jp208775x
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
今堀博
中科院分区：
文献类型：
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作者：
梅山有和;広瀬公平;野田啓;松重和美;宍戸哲也;林宏暢;俣野善博;小野昇;今堀博
利用热转化策略合成了一种新型的低禁带结构聚合物，该聚合物的主链上含有异硫杂环芳烃(ITN)二聚体和苯并二噻吩环(BDT)。首先，通过钯(0)催化的Stille偶联反应，合成了一种主链结构交替的双环[2.2.2]辛二烯熔融噻吩二聚体和BDT(PPBIBDT)先驱体。然后，加热旋转涂覆在玻璃板上的黄色PPBIBDT薄膜，得到一种不溶于任何有机溶剂的深蓝色PBIBDT薄膜。PPBIBDT的热重分析表明，失重率为14%，起始温度为230°C，证实了热诱导的逆向Diels-Alder反应的发生。与先驱体聚合物PPBIBDT相比，PBIBDT薄膜在可见光和近红外区表现出红移、宽吸收，最大吸收峰位于706 nm，吸收峰位于445 nm。在主链中引入ITN二聚体单元，由于具有稳定的奎宁共振结构，降低了带隙。PBIBDT的场效应空穴迁移率为1.1×10-4cm2V-1s-1，开关比为2.5×102，而基于PPBIBDT的器件没有表现出p型和n型响应。基于PBIBDT和[6，6]-苯基-C61-丁酸甲酯(PCBM)的平面异质结结构制备了有机光伏器件，在标准AM1.5太阳光下(100 mW cm-2)显示出0.07%的功率转换效率。这些结果将为热致低禁带聚合物器件的设计提供基础信息。
Thermal conversion strategy has been utilized in the synthesis of a novel low bandgap polymer containing isothianaphthene (ITN) dimer structure and benzodithiophene (BDT) unit in the backbone (PBIBDT). First, a highly soluble precursor polymer with an alternating main chain structure of bicyclo[2.2.2]octadiene-fused thiophene dimer and BDT (PPBIBDT) was synthesized by a palladium(0)-catalyzed Stille coupling reaction. Then, heating of the yellow PPBIBDT film spin-coated on a glass plate yielded a dark blue film of PBIBDT that was insoluble in any organic solvents. Thermogravimetric analysis of PPBIBDT showed 14% weight loss with an onset at 230 °C, corroborating the occurrence of the thermally induced retro-Diels–Alder reaction. The PBIBDT film showed red-shifted, broad absorption in the visible and near-infrared regions with a maximum at 706 nm compared to the precursor polymer PPBIBDT with an absorption peak at 445 nm. The introduction of an ITN dimer unit in the backbone lowered the bandgap owing to the stabilized quinoid resonance structure. The field-effect hole mobility of PBIBDT was determined to be 1.1 × 10–4cm2V–1s–1with an on–off ratio of 2.5 × 102, while the PPBIBDT-based device revealed no p- and n-type responses. Organic photovoltaic devices were fabricated based on the planar heterojunction structure of PBIBDT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and showed a power conversion efficiency of 0.07% under standard AM1.5 sunlight (100 mW cm–2). These results obtained here will provide fundamental information on the design of thermally induced low bandgap polymers for device applications.