窄带隙共轭聚合物的合成及其光电性能研究

发布时间：2018-05-07 04:03

本文选题：非对称聚合物 + 场效应晶体管　；参考：《河北大学》2017年硕士论文

【摘要】：自21世纪以来,由于化石能源的不断消耗,能源枯竭、环境污染等问题日益严峻。寻找一种可代替化石能源的清洁能源势在必行,于是科学家将目光投向于清洁的太阳能。从此,太阳能电池成为各领域的研究热点。有机太阳能电池因低成本、轻柔、可印刷制备等优点,具有重要的应用前景。有机共轭材料作为一种新兴的功能材料,由于其具有丰富的光、电、磁等功能特性,已在有机太阳能电池(OSCs)和有机场效应晶体管(FETs)领域得到广泛的研究。然而提高有机太阳能电池的光电转换效率,从而提高太阳能的利用率仍是人们努力的方向。通过设计并合成具有窄带隙和较低的HOMO能级的有机共轭材料,优化分子结构,改善材料的各项性能,是提高太阳能电池效率的主要方法。本论文围绕新型共轭分子的设计、合成及其在有机场效应晶体管和有机太阳能电池中的应用展开研究工作,具体内容如下:1.成功设计并合成了一个以噻吩和噻唑作为桥联基团的非对称DPP共轭聚合物。对其光电性能的研究发现,不对称DPP聚合物具有较窄的带隙,合适的HOMO与LUMO能级(-5.48 eV与-4.03 eV),以及高的空穴迁移率(3.05 cm2 V-1 s-1)。将其作为电子给体应用于太阳能电池中,能量转换效率高达5.9%,显示出较高的填充因子0.66与短路电流密度12.0 mA cm-2。通过对活性层形貌的研究发现,非对称聚合物与PC71BM共混的薄膜中表现出大的相分离尺寸,导致其相对低的光电流。以上结果表明,通过将不同芳香基团连接在聚合物主链是调节能级,实现高性能有机光伏器件的一种有效方法。2.通过在傒酰亚胺分子(SdiPBI)中引入两个氰基基团,成功设计并合成了一种具有低LUMO能级(-4.56 eV)的小分子受体材料(SdiCNPBI)。对其光电性能研究发现,SdiCNPBI分子在溶液和薄膜中具有相似的吸收光谱。由于强吸电子基团氰基的作用,SdiCNPBI的HOMO和LUMO能级显著降低,分别为-6.59 eV和-4.56 eV。将该分子作为电子受体应用于非富勒烯太阳能电池中,与不含氰基的电子受体对比,成功实现能量转换效率从0.1%提高到1.4%。采用光致发光技术(PL)进一步证实了有效的电荷分离。以上结果证明,扭曲的双PBI单元有效阻止共混薄膜中分子的聚集,缺电子基团的引入降低分子能级从而提高电荷分离驱动力,最终实现了给体材料的LUMO能级低于-4.0 eV下优异的光电性能。
[Abstract]:Since the 21st century, due to the constant consumption of fossil energy, energy depletion, environmental pollution and other increasingly serious problems. It is imperative to find a clean alternative to fossil energy, so scientists look to clean solar energy. Since then, solar cells have become a research hotspot in various fields. Organic solar cells have important applications due to their advantages of low cost, softness, printability and so on. As a new functional material, organic conjugated materials have been widely studied in the field of organic solar cells (OSCs) and airfield effect transistors (FETs) because of their rich optical, electrical and magnetic properties. However, improving the photovoltaic conversion efficiency of organic solar cells and thus improving the utilization rate of solar energy is still the direction of people's efforts. By designing and synthesizing organic conjugated materials with narrow band gap and lower HOMO energy level, optimizing the molecular structure and improving the properties of the materials are the main methods to improve the efficiency of solar cells. This thesis focuses on the design, synthesis and application of novel conjugated molecules in organic solar cells and airfield effect transistors. The main contents are as follows: 1. An asymmetric DPP conjugated polymer with thiophene and thiazole as bridging group was successfully designed and synthesized. It is found that asymmetric DPP polymers have narrow band gap, suitable HOMO and LUMO energy levels of -5.48 EV and -4.03 EV, and high hole mobility of 3.05 cm2 V-1 s-1C. When it is used as an electron donor in solar cells, the energy conversion efficiency is as high as 5.9, showing a high filling factor of 0.66 and a short-circuit current density of 12.0 Ma cm-2. By studying the morphology of the active layer, it is found that the large phase separation size in the films mixed with asymmetric polymer and PC71BM leads to a relatively low photocurrent. The results show that connecting different aromatic groups to the main chain of the polymer is an effective way to achieve high performance organic photovoltaic devices by regulating the energy levels. By introducing two cyanide groups into SdiPBI, a small molecule receptor material with low LUMO level (-4.56 EV) was successfully designed and synthesized. It is found that SdiCNPBI molecules have similar absorption spectra in solution and thin films. The HOMO and LUMO energy levels of SdiCNPBI were significantly decreased to -6.59eV and -4.56eV, respectively. The molecule was used as an electron receptor in non-fullerene solar cells, and compared with the electron receptors without cyanide group, the energy conversion efficiency was improved from 0.1% to 1.4%. The effective charge separation was further confirmed by photoluminescence (PL) technique. The above results show that the twisted double PBI element effectively prevents the molecular aggregation in the blend film, and the introduction of the electron deficient group reduces the molecular energy level, thus increasing the charge separation driving force. Finally, the LUMO energy level of the donor is lower than -4.0 EV.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O633.5

【参考文献】