氟原子的位置和数目对D-A共轭聚合物性能的影响

发布时间：2018-06-29 04:19

本文选题：氟原子 + 平面性　；参考：《陕西师范大学》2016年硕士论文

【摘要】：人类生存依赖于石油、煤炭等有限的能源,然而随着过度消耗,造成了地球上的资源匮乏和环境污染,危害到人类身体健康。太阳能作为最佳的代替者,受到众多研究者的关注。太阳能电池由最初的硅电池到现今的有机太阳能电池,经过了近半个世纪的发展。有机太阳能电池相较于已经商业化并投入实际使用的无机电池相比,有原料易得,成本低,可制备柔性器件等优点。有机太阳能电池活性层中给体材料研究对电池起着决定性作用,进一步提高电池的光电转换效率要解决的关键问题是活性层给受体材料对光的吸收利用率。设计窄带隙宽吸收高吸光率的分子有利于电子离域以及载流子的迁移,提高短路电流。改善分子主链平面性,通过设计类似共平面大的芳香结构主干可实现分子平面性良好的目标,也可在侧链或者引入杂原子、基团增加或减小位阻来改善聚合物链的主干结构扭转角,增强分子间的π-π堆积性,提高载流子迁移率,最终也可提高短路电流。本论文在明星分子聚噻吩类衍生物以及二烷氧基苯类与苯并噻二唑的聚合物两种分子的基础上,为改善分子平面性,增大电流,在分子不同位置引入了氟原子并改变分子中氟原子数目。通过Stille交叉偶联反应分别合成制备了PTCBT、 PTCFBT、和PFTCBT 以及 PFPTBT、PFPFTBT、PPFTBT两组六种聚合物,制备体异质结太阳能电池,并对电池的性能进行研究,具体工作如下：(1)通过热重分析测定这三种聚合物都有良好的热力学稳定性；经紫外吸收分光光度计测定,其中引入氟原子的PTCFBT和PFTCBT两个聚合物的吸收边分别在700nm和760nm。聚合物PTCBT、PTCFBT、PFTCBT对应的膜吸收最大吸收峰为552nm,516nm,586nm。通过循环伏安法测定,聚合物PTCBT、PTCFBT、 PFTCBT的LUMO能级分别为-2.85 eV,-2.94 eV,-2.87 eV。HOMO能级分别为-5.26 eV,-5.64 eV,-5.49 eV。器件光伏性能测定基于三种聚合物为给体材料的电池能量转换效率分别为4.70%、4.99%、5.93%;与受体材料PC71BM混合后形貌良好,粗糙度较小；XRD测试表明聚合物PTCFBT、PFTCBT引入氟原子有利于分子晶体堆积。(2)通过紫外吸收分光光度计测定,聚合物PFPFTBT、PFPTBT、PPFTBT对应的膜吸收最大吸收峰为595nm,527nm,642nm,氟原子引入位置不同对分子带隙影响不同;通过循环伏安法测定,聚合物PFPFTBT、PFPTBT、PPFTBT的LUMO能级分别为-3.0 eV,-2.96 eV,-2.98 eV, HOMO能级分别为-5.76 eV,-5.75 eV,-5.31 eV,氟原子可降低分子能级,数目越多,降低程度越大,氟原子所在位置可与C、s等原子形成的共价键改变分子平面性,提高短路电流；器件光伏性能测定基于三种聚合物为给体材料的电池能量转换效率分别为3.93%%,6.40%,9.39%。
[Abstract]:Human survival depends on limited energy sources such as oil and coal. However, with the excessive consumption, the resources on the earth are scarce and the environment is polluted, which is harmful to human health. As the best substitute, solar energy has attracted many researchers' attention. Solar cells have been developed from silicon cells to organic solar cells for nearly half a century. Compared with the inorganic cells which have been commercialized and put into practical use, organic solar cells have the advantages of easy availability of raw materials, low cost and the ability to fabricate flexible devices. The study of donor material in the active layer of organic solar cell plays a decisive role in the battery. The key problem to be solved in further improving the photovoltaic conversion efficiency of the cell is the utilization ratio of light absorbed by the active layer to the recipient material. The design of narrow band gap wide absorption molecules with high absorptivity is beneficial to electron delocalization and carrier migration, and to increase short circuit current. To improve the planarity of the molecular main chain, the goal of good molecular planarity can be achieved by designing the backbone of aromatic structures similar to the coplanar size, or by introducing hetero atoms into the side chain, Increasing or decreasing the steric resistance of the group can improve the torsion angle of the main structure of the polymer chain, enhance the 蟺-蟺 accumulation between molecules, increase the carrier mobility, and finally increase the short circuit current. In this paper, on the basis of star molecule polythiophene derivatives and dialkoxy benzenes and benzothiadiazole polymers, in order to improve the molecular flatness and increase the current, Fluorine atoms are introduced and the number of fluorine atoms in the molecules is changed. Six kinds of polymers, PTCBT, PTCFBT, PFTCBT and PFPTBTPFPFTBT, were synthesized by Stille cross-coupling reaction to prepare heterojunction solar cells. The main results are as follows: (1) the thermodynamics stability of the three polymers was determined by thermogravimetric analysis, and the absorption edge of the fluorinated PTCFBT and PFTCBT were measured at 700nm and 760nm by UV absorption spectrophotometer. The maximum absorption peak of PFTCBT was 552 nm ~ 516 nm ~ (-1) ~ 586 nm ~ (-1). By cyclic voltammetry, the LUMO levels of the polymer PTCBTT PTCFBTand PFTCBT are -2.85 EV ~ 2.94 EV ~ 2.87 EV ~ (-1) -5.64 EV ~ (-1) -5.49 eV, respectively. The energy conversion efficiency of the battery based on three kinds of polymers was 4.70 and 4.99 respectively, and the photovoltaic performance of the device was 5.93.The photovoltaic device was mixed with the acceptor PC71BM with good morphology and low roughness. XRD results show that the introduction of fluorine atoms into PFTCBT is beneficial to the accumulation of molecular crystals. (2) by UV absorption spectrophotometer, the maximum absorption peak of PPFTBT / PFPFTBT / PFPTBTT / PPFTBT is 595 nm / 527 nm / m ~ (62) nm, and the influence of fluorine atoms on the band gap is different; By cyclic voltammetry, the LUMO and Homo levels of PPFTBT / PFPFTBT / PFPTBTT / PPFTBT were -3.0 EV ~ 2.96 EV ~ 2.96 EV ~ 2.98 EV and -5.76 EV ~ 5.75 EV ~ 5.75 EV ~ 5.31 EV, respectively. The location of fluorine atoms can change the plane of molecules and improve the short-circuit current with the covalent bonds formed by the atoms such as Cons, and the photovoltaic properties of the devices are determined. The energy conversion efficiency of the battery based on the three kinds of polymers is 3.93 and 6.40and 9.39, respectively.
【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O631.3

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