【作者】 段春晖；

【导师】 曹镛；

【作者基本信息】 华南理工大学 ， 材料学， 2013， 博士

【摘要】 近三十年来，半导性的共轭聚合物和共轭小分子等有机材料因其在太阳电池和发光二极管等光电器件中的巨大应用前景而引起了学术界和产业界的持续关注。在这些材料中，具有水/醇溶性的共轭有机材料因其优异的光电性能、独特的溶解性、优异的界面修饰性能等优势而展现了广泛的用途。另一方面，有机/聚合物太阳电池（OPVs）因其低成本、可大面积加工等优势而备受关注。得益于性能优异的新型聚合物给体材料的研发，OPVs的能量转换效率不断攀升，正在逐渐接近其商业化的门槛。本论文主要涉及两个方面的研究：一是针对传统的水/醇溶性共轭聚合物所存在的问题，发展新型的水/醇溶性的共轭有机材料并对他们的新应用进行探索；二是为了开发新型的高性能的OPVs给体材料，发展了一个区别于传统的线性聚合物的全新材料体系。在第二章，我们为了克服传统的共轭聚电解质中自由移动的反离子对光电器件的不利影响和中性的水/醇溶共轭聚合物溶解性不足的缺陷，发展一系列的两性共轭聚电解质。两性离子基团的引入，不仅保证了聚合物在极性溶剂中的良好溶解性，而且最大程度地限制了离子的运动范围。我们发现两性共轭聚电解质作为界面修饰层应用于聚合物发光二极管（PLEDs）和OPVs时，能比传统共轭聚电解质更大幅度地提升器件的性能。以两性共轭聚电解质为基础，我们还研究了共轭主链结构对水/醇溶性共轭聚合物的界面修饰性能的影响。我们发现界面层与活性层之间的能级是否匹配，是决定水/醇溶性共轭聚合物能否充分发挥其界面修饰功能的重要因素之一。这对未来新界面材料的开发和光电器件的设计具有重要的意义。在第三章，我们设计并合成了一种磷酸酯功能化的醇溶性富勒烯衍生物，并研究了其作为ITO的修饰层在倒置OPVs中的应用。我们发现这类材料可以显著降低ITO的功函数，促进ITO对电子的收集，使器件的能量转换效率获得了30%的提升。这项研究表明，集理想的能级、优异的电子收集能力和良好的醇溶性等优点于一身的水/醇溶性富勒烯衍生物是一类非常有潜力的应用于OPVs的界面材料。在第四章，为了制备可采用环境友好溶剂加工的高效OPVs，我们设计并合成了胺基功能化的醇溶性窄带隙共轭聚合物和富勒烯衍生物。出乎意料地，这些材料作为活性层应用于OPVs时，完全没有光电流输出，而作为电子收集层时他们都能显著提升器件性能。经过深入研究，我们揭示了脂肪胺的空穴陷阱本质及脂肪胺与富勒烯的复合化作用。正是这两个原因，使得这类可环境友好溶剂加工的材料无法作为活性层应用于OPVs；而作为界面层时，脂肪胺对富勒烯的界面掺杂以及空穴陷阱在金属电极附近的累积又恰恰是他们的重要工作机制。这些发现对发展环境友好加工OPVs和理解水/醇溶性界面修饰材料的工作机制具有重要意义。在第五章，我们发展和丰富了一个有别于传统线性共轭聚合物的新材料体系—受体悬挂式D-A共轭聚合物，作为给体材料用于OPVs。与研究最多的线性D-A聚合物不同，受体悬挂式D-A共轭聚合物的主链全部由D单元组成，而将受体悬挂在侧链上。这种独特的分子结构赋予受体悬挂式D-A共轭聚合物一系列独特的优点，如：可通过调节给体单元和受体单元方便地实现对吸收光谱、光学带隙和能级结构的调控，更好的多方向电荷传输性能，更好的溶解性等。将具有优异的光电性能的分子构筑单元（硅芴、咔唑、茚芴等）与受体悬挂式D-A共轭聚合物的分子设计相结合，通过在聚合物的共轭侧链引入不同的受体单元（丙二腈、1,3-二乙基硫代巴比妥酸、3-（二氰基亚甲基）茚酮等）、增加D-π-A生色团的含量、改变烷基侧链等手段，我们发展了一系列新材料，实现了对聚合物的吸收光谱、光学带隙、能级结构实现了精确有效的调控。利用受体悬挂式D-A共轭聚合物的研究平台，我们为拓宽共轭聚合物的吸收光谱提出了一个新方法，即通过引入两个吸电子能力不同的受体单元，在同一个聚合物中构建两种不同的D-π-A生色团，使共轭聚合物的吸收光谱实现了对全部整个可见光区的覆盖并延伸到近红外光区。作为OPVs的给体材料，受体悬挂式D-A共轭聚合物表现出了良好的光伏性能，所有的器件都有很高的开路电压，最高能量转换效率达到4.47%。该系列工作为OPVs发展了一个新的给体材料体系。更多还原

【Abstract】 Semiconducting conjugated polymers and small molecules have attracted growingattentions due to their great application potentials in optoelectronic devices such as solar cellsand light-emitting diodes over the past decades. Among them, water/alcohol-soluble organicconjugated materials have exhibited wide applications owing to their excellent optoelectronicproperties, unique solubility and outstanding interfacial modification functions. On the otherhand, organic/polymer solar cells (OPVs) have also gained much attentions due to their lowcost and compatibility with large-scale processing. The power conversion efficiencies ofOPVs have approached to the commercialization threshold mainly benefiting from thedevelopment of new conjugated polymer donors.The studies demonstrated in this thesis include two parts. The first part is thedevelopment of new water/alcohol soluble conjugated organic materials and the explorationof their new applications, which can overcome the shortcomings of traditional water/alcoholsoluble conjugated polymers. The second part is the development of a new high-performanceconjugated polymer family for use as donors in OPVs, which are different from theextensively studied linear conjugated polymers.In chapter2, a series of zwitterionic conjugated polyelectrolytes were developed withthe aim at overcoming the negative influences caused by the mobile counterions in traditionalconjugated polyelectrolytes and the limited solubility of neutral water/alcohol solubleconjugated polymers. The introduction of zwitterionic groups not only endowed the resultingpolymers with excellent solubility in polar solvents but also suppressed the movement of ions.It was found that zwitterionic conjugated polyelectrolytes is superior to tradition conjugatedpolyelectrolytes when used as interfacial modification layer in polymer light-emitting diodes(PLEDs) and OPVs. The effects of chemical structures of conjugated main chains on theinterfacial modification properties of water/alcohol conjugated polymers. It was revealed thatthe energy alignment between interfacial layer and active layer is a key factor that determinedthe interfacial modification abilities of water/alcohol soluble conjugated polymers. Thisdiscovery provided a guideline to design new interfacial materials and optoelectronic devices. In chapter3, a phosphate group-containing alcohol soluble fullerene derivative wasdeveloped to apply as modifier for indium tin oxide (ITO) in inverted OPVs. It was foundthat this fullerene derivative can lead to the decrease of work function of ITO significantly,and consequently enhance the electron collection in ITO electrode and improve the powerconversion efficiency of OPVs by30%. This study suggested that water/alcohol solublefullerene derivatives which combined ideal energy levels, excellent electron collectingabilities and unique solubilities are very promising interfacial materials for OPVs.In chapter4, an alcohol-soluble narrow-band gap conjugated polymer and a fullerenederivative which were functionalized with amino-group were developed towardenvironmentally-friendly solvents processed OPVs. Despite positive expects, the blendsystem was not able to lead to any output of photocurrent when they were incorporated intoOPVs as active layer. However, both of them performed well as electron-collecting layer inOPVs. In-depth studies revealed the hole-trap nature of aliphatic amine and the complexationbetween amine and fullerene, which suppressed the photocurrent output when they werepresence in active layer. On the other hand, the n-doping of fullerene by aliphatic amine andthe accumulation of hole traps adjacent to metal electrode are beneficial to the deviceperformances. The studies in this chapter are very important to develop new materials forenvironmentally-friendly processed OPVs in the future and to understand the workingmechanisms of water/alcohol soluble interfacial materials.In chapter5, a serious of acceptor-pended D-A conjugated polymers, which differedfrom extensively studied linear conjugated polymers were developed for use as donors inOPVs. Acceptor-pended conjugated polymers have a lot of advantages, such as facilities forcontrolling absorption spectra, band gap and energy level by simple chemical modification,better isotropic charge transport properties and better solubilities. A large family ofconjugated polymers was developed by combining the advantages of acceptor-pendedmolecular design and several promising building blocks (such as silicafluorene, carbazole andindenofluorene). The absorption spectra, band gaps and energy levels were finely tuned byattaching different acceptor groups (such as malononitrile,1,3-diethylthiobarbituric acid,2-(1,2-dihydro-1-oxoinden-3-ylidene)) onto the end of the conjugated side chains of the polymers, and by enhancing the concentration of D-π-A chromophores and changing thealkyl side chains. Moreover, two conjugated polymers whose absorption spectra covered thewhole visible light region and even extended into infrared light region were developed byconstructing two different D-π-A chromophores on one polymer chain, which provided a newapproach to extend the absorption spectra for conjugated polymers. All of theacceptor-pended conjugated polymers exhibited moderate performance as donors in OPVswith high open-circuit voltage and highest power conversion efficiency of4.47%. The studiesin these chapters developed a new system of donor materials for OPVs.更多还原