【作者】 周天雷；

【导师】 王悦；

【作者基本信息】 吉林大学 ， 有机化学， 2011， 博士

【摘要】 本文设计、合成了14种丙二腈取代烷基喹吖啶酮化合物,并对其光物理特性、热力学特性、电化学特性、单晶结构、自组装特性、分子轨道分布及其体异质结光伏器件的制备、优化和机理等进行了研究,讨论了材料分子的结构、自组装特性等与光伏器件性能之间的关系,获得了一些具有较好光伏特性的小分子受体材料。1、合成了8种双丙二腈取代烷基喹吖啶酮化合物,研究了丙二腈基团的引入对烷基喹吖啶酮材料性能的影响。该系列化合物具有较窄的带隙,较好的溶液加工特性,较高的热稳定性,可逆的电化学氧化还原性能以及与P3HT匹配较好的分子轨道能量。是一类适合于有机体异质结太阳能电池的小分子受体材料。2、通过X-射线单晶衍射、XRD及DSC等方法分别研究了丙二腈取代烷基喹吖啶酮系列化合物的分子构型与分子堆积方式、晶体层状结构与二维生长优势,以及无定形冷却与热致结晶的特性。丙二腈基团的引入使喹吖啶酮刚性核发生较大程度的弯曲,降低分子间π…π相互作用力,进而降低分子的结晶能力。分子间其它各种弱相互作用的竞争使不同分子具有不同的聚集特性和结晶特性,该研究对丙二腈取代烷基喹吖啶酮系列化合物在有机体异质结太阳能电池中的应用和对电池活性层形貌的控制与理解等方面有重要的意义。3、通过紫外-可见吸收光谱、原子力、XRD等方法考察了系列丙二腈取代烷基喹吖啶酮受体材料在有机体异质结太阳能电池活性层中的吸收特性和聚集特性,同时采用空间电荷限制电流(SCLC)方法估算了材料的电子迁移率。以P3HT为给体制备了基于丙二腈取代烷基喹吖啶酮受体材料的体异质结光伏器件并对器件性能进行了表征。结果表明,通过引入吸光型受体材料可以明显增加光伏器件对太阳光谱的响应范围,取代烷基的长度对材料的迁移率、成膜特性、与给体分子的相互作用以及器件性能有较大影响。其中以DCN-8CQA为受体的光伏器件实现了1.57%的光电转换效率,仅次于国际报道的非富勒烯小分子受体材料体异质结光伏器件性能的最高值2%,证明丙二腈取代烷基喹吖啶酮是一类较好的小分子光伏受体材料。4、设计合成了一系列单丙二腈取代烷基喹吖啶酮化合物。系统研究了这些化合物的光物理、热力学、电化学以及光伏性能。单丙二腈取代烷基喹吖啶酮较双丙二腈取代烷基喹吖啶酮化合物有更高的LUMO能量,采用单丙二腈取代烷基喹吖啶酮化合物制备出的光伏器件具有显著提高的开路电压。通过XPS分析证明在有机/铝界面处受体分子与金属铝的相互作用以及氧化铝薄层的形成可能也是引起开路电压提高的重要原因之一。该研究注重于体异质结光伏电池有机/电极界面,对进一步提高开路电压,提高电池光电转换效率的研究具有重要的指导意义。更多还原

【Abstract】 Solar power has attracted much attention due to its pollution free, widespread and non-expensive characters. It may become one of the major ways for people to get energy in the near future. Nowadays, the commercialized solar cells are based on silicon material. Although such solar cell has the power conversion efficiency as high as 20%, the high cost and heavy work in producing silicon solar cell has made this technology difficult to popularize. Thus, the organic solar cell, which is cheap, less complicated and easy to carry with, has aroused great interest of the scientists. The most common and promising organic solar cell is a bulk-heterojunction type with P3HT as the donor and fullerene derivatives as the acceptor. Although fullerene and its derivatives are proved to be the most efficient acceptor for organic solar cell, their weak absorption in the solar spectrum has seriously limited the improvement of power conversion to solar energy. Then, it will be more meaningful to develop novel organic none-fullerene small molecule acceptors since they are more flexible in molecule modulation, synthesis and more possible to achieve proper energy level and improved absorption. Up to now, there have been some novel acceptor materials reported, however, the efficient one with power conversion efficiency more than 1% is still scarce. Thus, in this thesis, I have synthesized a series of novel organic non-fullerene acceptors by modulation to the typical dye material alkyl-quinacridone and characterized its photovoltaic properties. A careful study of the open circuit voltage was also carried out.1. In Chapter Two, we had designed and synthesized 8 malononitrile substituted alkyl-quinacridone compounds and studied their photophysical, electro-chemical and thermo-dynamical properties. A theoretical calculation to investigate their electron structure was also included. By introducing the electron drawing malononitrile groups, the absorption of alkyl-quinacridone has significantly red-shifted, which has testified the feasibility of obtaining narrow band gap material by enhancing the intramolecular charge transfer transition effect. In addition, these malonitrile substituted alkyl-quinacridone compounds have relatively good solvability, high thermo-stability, stable electro-chemical properties and proper energy level match to P3HT donor showing that they are good candidates for organic bulk-heteroj unction solar cell.2. In Chapter Three, the structure, packing styles and crystallization properties of malononitrile substituted alkyl-quinacridone were closely studied. It was found that the substitution by malononitrile has caused a large bend to the quinacridone molecule, which has significantly weakened the intermolecularπ...πinteractions and decreased the crystallization. Besides, the competition of alkyl-alkyl and other weak interactions are responsible for the 2-dimentional growth character and the amorphous cooled aggregates of some malononitrile substituted quinacridone compounds.3. In Chapter Four, the bulk hetero-junction solar cells using P3HT as the donor and molononitrile substituted alkyl-quinacridone as the acceptor were prepared and characterized. By using an acceptor with intense absorption in the visible spectrum, the solar spectrum response range of the former P3HT:PCBM device has been expanded from 650 nm to about 700 nm. One of the device using DCN-8CQA as the acceptor has achieved the short circuit current density of 5.73 mA/cm2 and the power conversion efficiency of 1.57% with external quantum efficiency more than 15% at wavelength region more than 650 nm. This has proved the feasibility of improving the performance of device by using acceptors that has intense absorption in visible spectrum. Moreover, the impact of alkyl chain length on the molecule aggregating behaviors, the morphology of the active layer and the corresponding performance of the device are also discussed. The conclusion we have is that a good-performed solar cell should have a moderate molecule aggregation in the active layer.4. In Chapter Five, we have synthesized a series of mono-malononitrile substituted alkyl-quinacridone compounds. Their thermo-dynamic, photophysical and photovoltaic properties were studied. By using mono-malononitrile substituted alkyl-quinacridone compounds, all solar cells fabricated have a prominent improved opencircuit voltage than the device using corresponding double-malononitrile substituted alkyl-quinacridone compounds. Notably, the device using SCN-8CQA has achieved the open circuit voltage as high as 0.66 V. By electro-chemical analysis and XPS method, we found that the large open circuit voltage of these devices not only originates from the higher LUMO level of the mono-malononitrile substituted alkyl-quinacridone compounds, but also originates from their stronger interaction with cathode Al and the existence of Al2O3 thin layer at the organic/electrode interface. This work has provided valuable support to the research and improvement of open circuit voltage of the organic solar cell.In conclusion, we have obtained a series of novel non-fullerene small molecule acceptor materials with narrow band gap, good thermo-stability, proper energy level matching and high power conversion efficiency. These materials are powerful proof for the strategy of using donor and acceptor co-absorption to improve the performance of the device. As a novel type of non-fullerene small molecule acceptor materials and semiconductors, they also have promising potential in application.更多还原