噻吩并异靛蓝基有机半导体材料的设计、合成及其场效应晶体管性能研究
文献类型：学位论文
| 作者 | 赵娜 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-11 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 北京 |
| 导师 | 万晓波 |
| 关键词 | 有机场效应晶体管 异靛蓝 D-A型共轭聚合物 有机半导体材料 |
| 学位专业 | 化学工程 |
| 中文摘要 | 自1945年肖克利提出场效应晶体管的概念以来，这个领域就吸引了全世界的广泛关注并极大地促进了科技的进步。随着有机材料半导体特性的发现，人们开始利用有机材料代替无机材料制备场效应晶体管。自从1986年首次报道第一个真正意义上的有机场效应晶体管（OFET），作为新一代半导体晶体管的有机场效应晶体管取得了长足的发展，凭借其独特的性能优势，在大面积、柔性化和低成本有源矩阵显示、射频标签等领域显示出良好的商业应用前景和价值。 异靛蓝（Isoindigo）是一种性能优良的电子受体材料，近年来作为有机光电器件中的活性层材料逐渐引起了人们的广泛关注。其有机太阳能电池器件的光电转化效率最高可达9.1 %，场效应晶体管器件的空穴迁移率最高已达到14.4 cm2V-1s-1，电子迁移率也已达到1.74 cm2V-1s-1。异靛蓝可以进行大规模合成，且产率较高，因而其小分子及共聚物光电材料都得到了极大的发展。 本论文主要集中在基于噻吩并异靛蓝分子的共轭聚合物有机场效应晶体管材料的设计，合成及性能研究上，主要研究内容包括以下几个方面： 首先，由于异靛蓝本身的非平面结构，其分子的堆积结构会受到一定的影响，从而影响其器件性能。我们希望在保持异靛蓝类材料优良光电性能的同时，对异靛蓝的中心结构进行化学结构的修饰，通过芳香并环的引入不仅可以增加异靛蓝分子的共轭长度，从而提高其共聚物的分子内载流子传输能力，还可以得到更好的π-π堆积结构，从而提高其共聚物的分子间载流子传输能力。通过不断尝试，成功开发出一种方便高效的噻吩并异靛蓝分子的合成方法。首先进行氯代反应，通过氯原子将5-氨基苯并噻吩上较为活泼的4位进行保护，从而使接下来的傅-克反应发生在6位，最终得到直线型噻吩并异靛蓝分子，并采用类似方法合成出苯并异靛蓝分子。还对新开发的异靛蓝合成方法的反应机理进行了研究，该反应包含吲哚-2-酮的烷基化反应以及其烷基化产物在碱性条件下的空气中的氧化反应，以及最后的偶联反应。采用类似方法，我们合成了具有更长共轭体系的苯并呋喃并异靛蓝和苯并噻吩并异靛蓝分子，并对其光电性能和有机场效应晶体管器件性能进行了研究，二者均为良好的n型有机场效应晶体管材料。 通过对噻吩并异靛蓝分子和苯并异靛蓝分子的光电性能研究，我们发现在异靛蓝结构两端并上芳香环，可以大幅度加强其分子内电荷转移过程，同时，其电化学氧化还原可逆性也可以得到提高，这些都有助于获得较好的OFET器件性能。其中噻吩并异靛蓝分子易于进行修饰，可应用于寡聚物及聚合物场效应晶体管材料的研究。 在此基础上，我们尝试不同方法在噻吩并异靛蓝分子两端上溴，使其可作为共聚单体来制备共轭聚合物。然而，在噻吩并吲哚二酮分子上溴得到的产物为噻吩β-位溴代，最终通过Stille偶联聚合得到的是交叉共轭的聚合物，其紫外可见吸收光谱没有表现出明显的红移，场效应晶体管性能也不尽如人意。 通过文献的整理分析，我们设计了新的α-位溴代噻吩并异靛蓝合成方法，成功合成出完全共轭的噻吩并异靛蓝基D-A型共聚物PTII-T和PTII-TVT-8，由于具有较低的LUMO能级，其溶液加工的有机场效应晶体管器件在空气中都表现出稳定的性能。两种完全共轭的聚合物的场效应晶体管迁移率均远远高于交叉共轭的聚合物器件。其中，PTII-T表现出均衡的电子和空穴迁移率，分别为0.029和0.018 cm2V-1s-1，而PTII-TVT-8则表现出更好的空穴迁移率（0.037 cm2V-1s-1）。 |
| 英文摘要 | Organic field-effect transistors (OFETs), using π-conjugated systems including small molecules, oligomers and polymers as the active semiconducting layer, have attracted particular attention as the key elements for realizing the next generation of electronics, that is, flexible and printed organic electronics. It was in the 1980s when the first application of their semiconducting nature to switching devices (i.e., transistors); use of poly(thiophene) in OFETs was reported. However, the properties of these prototypical OFETs including field-effect mobility and environmental stability were poor, and thus they were far from the practical use. Researchers have recently explored the promise of these historical pigments in the organic electronics field by successfully employing indigo as the semiconducting material in high-performance organic field effect transistors (OFETs). Indigo does not possess the characteristics of a good building block owing to its discontinuous π-conjugation and thus its widespread application in materials for organic electronics is limited. However, its structural isomer isoindigo, which has also been used previously in the dye industry, has many desirable attributes that have made it the subject of recent investigations. The unique structure of isoindigo imparts a strong electron withdrawing character owing to conjugation of the lactam rings in conjunction with an extended delocalized π system throughout the bis-oxindole framework. However, in many cases, isoindigo was directly used as the building block for oligomers or polymers, and less attention was paid on the manipulation on its core structure. Still, modification on isoindigo core may have dramatic influence on its electric properties. We design and synthesize a novel thiophene-fused isoindigo derivative. By fusing a thiophene ring onto the isoindigo core, the intramolecular charge transfer process is strengthened and the electrochemcial reversibilty is improved, which indicate that this novel insoindigo derivative might be a promising building block for organic electronics. Furthermore, a novel and mild way was found towards this isoindigo derivative. The alkylation, oxidation and condensation of thieno[2,3-f]indol-6(7H)-one were completed in a one-port reaction to give the desired compound, which has not been reported before. The mechanism for this reaction is discussed. Start from an commercial available compounds, after similar route, ultimately, two extended conjugated system with isoindigo core, namely C20-DBTII and C20-DBFII, were obtained. OFET devices based on C20-DBTII and C20-DBFII were fabricated via solution spin-coating. The two compounds exhibit good ambipolar and n-type properties respectively at ambient conditions. A series of donor-acceptor (D-A) type of conjugated polymers based on novel thiophene-fused isoindigo (TII) were designed and synthesized via palladium catalyzed Stille copolymerization. We found that the redesign of the synthesis of brominated TII was necessary, and the α-bromination had to be installed at the very beginning, or β-brominated TII was obtained, which only led to cross-conjugated polymers. Once the bromination was introduced at the correct position, fully conjugated D-A type polymer could be obtained. A series of fully conjugated polymers were obtained by Stille coupling polymerization of α-brominated TII with different donors, and among them, copolymers with thiophene (T) and (E)-1,2-bis(3-octylthiophen-2-yl)ethene (TVT-8) showed acceptable solubility and were suitable to fabricate solution-processable organic field-effect transistors (OFETs). Top-gate/bottom-contact (TG/BC) devices were constructed for the polymers to test their OFET performances. Both fully-conjugated polymers exhibit two-orders greater charge carrier mobilities than the cross-conjugated ones, and PTII-T shows balanced electron and hole mobility and PTII-TVT-8 is a p-type dominated semiconductor. These observations indicated that the developed TII unit that has improved coplanarity can be a promising building block for the construction of highly efficient conjugated polymers for OFET applications. |
| 学科主题 | 化学工程 |
| 语种 | 中文 |
| 公开日期 | 2016 |
| 源URL | [http://ir.qibebt.ac.cn/handle/337004/8086]  |
| 专题 | 青岛生物能源与过程研究所_生物基及仿生高分子材料团队 |
| 作者单位 | 中国科学院青岛生物能源与过程研究所 |
| 推荐引用方式 GB/T 7714 | 赵娜. 噻吩并异靛蓝基有机半导体材料的设计、合成及其场效应晶体管性能研究[D]. 北京. 中国科学院大学. 2015. |
入库方式： OAI收割
来源：青岛生物能源与过程研究所
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