【作者】 黄峻；

【导师】 陈军武；

【作者基本信息】 华南理工大学 ， 材料学， 2014， 博士

【摘要】 当今社会，能源危机已经成为人类面临的主要问题之一。随着工业和农业的发展，人们对于能源的需求量越来越大，能源问题使得人们迫切需要将视线转向新能源。在众多的新能源技术中，太阳电池技术占据着无法替代的位置。有机太阳电池则更是突显出了那些致力于发现新能源的人们的才智。聚合物太阳电池生产成本较为低廉，且可以以卷对卷方式大规模生产，鉴于此，聚合物太阳电池受到科学家们越来越多的关注。在材料学家看来，合成具有合适的能级、较宽的太阳光谱吸收范围和高空穴迁移的聚合物给体材料仍然是研究聚合物太阳电池的重中之重。本论文首先对明星聚合物给体材料进行了综述，基于这些材料的太阳能光电转换效率均超过了5%。为了更好理解聚合物结构与性能之间的关系，我们综述了超过150个聚合物给体材料。同时，对于这些聚合物进行了合理的分类，从而便于发现其中的规律与变化。基于噻吩的杂环化合物在有机太阳电池中的研究极为活跃，其既可以作为给电子单元，更可以作为受电子单元。在第三章中，我们通过在二噻吩并蒽上引入烷基链来改善单体的溶解性，并基于二噻吩并蒽设计且合成了两个D-A型窄带隙聚合物PADT-DPP和PADT-FDPP。这两个聚合物都有较宽的紫外可见光吸收，相应的光学带隙分别为1.44eV和1.50eV，利用他们制得的聚合物太阳电池器件的能量转换效率分别为3.44%和0.29%。原子力显微镜表明聚合物PADT-FDPP与PC71BM相分离不理想，所得的光电性能并不能让人满意。但当在制备器件的过程中加入1,8-二碘辛烷后，聚合物PADT-FDPP光电效率显著提升到2.62%，而聚合物PADT-DPP的光电转换效率则变化不大。通过部分优化的合成路线，本论文在第四章成功合成了二噻吩[3’,2’:3,4;2’’,3’’:5,6]苯并[1,2-c][1,2,5]噻二唑(DTBT)这个化合物，这是一个大平面结构、具有中等吸电子能力的电子接受单元。通过与不同的给电子单元组合，制备了四个中等带隙的D-A型交替共聚物。电化学测试表明，这四个聚合物具有几乎相同的HOMO能级。在这些聚合物中，聚合物DTBT-Th3溶液在室温甚至加热的条件下都存在较强的分子内聚集作用，且这种聚集作用对于光电子器件是有利的，使用氯苯作为加工溶剂时，基于聚合物DTBT-Th3的太阳电池效率高达6.81%。同时基于DTBT-Th4的场效应晶体管获得了最高的的空穴迁移率（0.74cm2/Vs）。聚合物DTBT-Th4, DTBT-TT, DTBT-Th5制备的光伏器件效果相对低一些，性能差异的原因通过相分离结构进行了探讨。以同分异构现象作为研究出发点，设计并合成了一种DTBT的同分异构体iso-DTBT（二噻吩[2’,3’:3,4;2’’,3’’:5,6]苯并[1,2-c][1,2,5]噻二唑），成功合成了其与联三噻吩和联四噻吩组成的交替共聚物iso-DTBT-Th3和iso-DTBT-Th4。这两个聚合物表现出与第四章同类聚合物完全不一样的吸收行为与能级，且器件结果表明iso-DTBT-Th3和iso-DTBT-Th4的光伏性能并不理想。为了理解造成这种差异的原因，使用了功能密度泛函和原子力显微镜进行了对比研究。另外，本论文还设计合成了另一大平面杂环：二噻吩[3,2-a:2’,3’-c]并吩嗪(DTQ)，并制备了其与联三噻吩和联四噻吩组成的交替共聚物DTQT-Th3和DTQ-Th4。这两个聚合物表现出极弱的分子内电荷转移，基于他们制得的太阳电池的光电转换效率仅为1.87%和0.60%。更多还原

【Abstract】 One of the main problems of the world facing today is the energy crisis. With thedevelopment of industry and agriculture, the world has consumed a great amount of energy.Among the numerous new energy technologies, solar cells occupy the irreplaceable position.Organic solar cells underline the ingenuity of those engaged in finding new sources of energy.Due to a low cost and roll-to-roll printing process, polymer solar cells have attracted muchattention. From the view of material scientists, the development of polymer donors withsuitable energy level, a broad absorption spectrum to solar light, and high carrier mobilityrepresents the “Holy Grail”.First, we summarized star polymer donors whose power conversion efficience were above5%, and more than150polymers could be included. Based on these analysis, the relationshipbetween structure and properties were discussed.Aromatic heterocyles based on thiophene are very important to construct many polymerdonors. In chapter3, two polymers based on anthradithiophene (ADT) were designed andsyntheszied. We introduced the alkyl chains into the ADT unit to improve the solubility.Polymers PADT-DPP and PADT-FDPP exhibited broad absorption bands and their opticalband gaps are1.44and1.50eV, respectively. In polymer solar cells, PADT-DPP andPADT-FDPP showed power conversion efficiency (PCE) of3.44%and0.29%, respectively.Atomic force microscopy revealed that the poor efficiency of PADT-FDPP should be relatedto the large two-phase separation in its active layer. If1,8-diiodooctane(DIO)was used as thesolvent additive, the PCE of PADT-DPP remained almost unchanged due to very limitedmorphology variation. However, the addition of DIO could remarkably elevate the PCE ofPADT-FDPP to2.62%because of the greatly improved morphology.In chapter4, dithieno[3’,2’:3,4;2’’,3’’:5,6]benzo[1,2-c][1,2,5]thiadiazole (DTBT), a largecoplanar acceptor, was successfully synthesized. Combined with four selected donors, fourmedium-bandgap polymers were obtained. Cyclic voltammetry revealed the polymers hadsimilar HOMO levels. Polymer DTBT-Th3in a solution showed very strong interchainaggregation at room temperature or elevated temperature, which could be benefit foroptoelectronic devices. Using cholrobenzene as the processing solvent, the best efficiency of6.81%was achieved for the DTBT-Th3-based polymer solar cells. The organic field-effecttransistors of DTBT-Th4gave the highest hole mobility of0.74cm2/Vs. Relatively, polymersDTBT-Th4, DTBT-TT, and DTBT-Th5did not show ideal photovoltaic performances. Theirmorphologies in blend films as measured by atomic force microscopy helped us to understand the existing difference.Isomerism can result in great influenece on the opotoelectronic property, thus an isormer ofDTBT, named as iso-DTBT, was sysnthesized for comparison study. We selected terthiopheneand quarterthiophene as the electron-donating units, from which two alternating copolymersiso-DTBT-Th3and iso-DBBT-Th4were prepared. To our surprise, polymers iso-DTBT-Th3and iso-DBBT-Th4showed totally different behaviors in absorption and energy level. Inpolymer solar cells, only poor photovoltaic performances could be exhibited. In order tounderstand these differences, we selected Density Functional Theory and atomic forcemicroscopy for further studies.In addition, another large coplanar heterocycle, dithieno[3,2-a:2’,3’-c]phenazine, wassynthesized. In combination with terthiophene and quarterthiophene, two alternatingcopolymers DTQ-Th3and DTQ-Th4were prepared. However, the two polymers showed weakintrachain charge transfer. In polymer solar cells, the two polymers displayed efficiencies of1.87%and0.60%, respectively.更多还原