光电活性聚合物纳米纤维和有机光伏器件的制备研究

发布时间：2018-07-08 12:11

本文选题：有机太阳能电池 + 光电活性聚合物　；参考：《浙江理工大学》2017年硕士论文

【摘要】：有机太阳能电池具有质轻、价廉以及可卷对卷大面积制备等优点,受到了人们的广泛关注。而在有机太阳能电池中,电荷是否能高效传输决定着电池的短路电流密度,而光电活性聚合物纳米纤维因为拥有极高的比表面积常被用来建立高效的电荷传输路径,所以在有机太阳能电池活性层中引进纤维可以提高器件的光电转化效率。但是目前所制备的光电活性聚合物纤维耐溶剂性能差,无法进行溶液再加工处理,限制了其在有机光伏领域中的进一步发展。本论文工作基于静电纺丝可便利制备核壳结构纳米纤维的技术,提出一种制备结构稳定且可溶剂再分散的光电活性聚合物纳米纤维的新策略。该策略利用可交联的光电活性聚合物,将其置于纳米纤维的核层,外面包裹钝性的聚合物,而后经内部交联和去除保护聚合物后制备获得。在本论文第一部分工作中,我们验证了这一策略。我们选用有机光伏领域典型的聚合物光伏材料PTB7,在其部分侧链末端引入端烯键,合成得到可交联的光电聚合物PTB7-Vn。性能研究发现在聚合物PTB7中引入一定量的末端双键其热学、光学及电化学性质并不会明显改变,并且聚合物PTB7-V0.05经紫外照射8小时后交联度高达90%以上。基于此,我们开始制备化学稳定的聚合物PTB7-V0.05纳米纤维的研究。我们利用单针头静电纺丝技术,在纺丝液中添加聚氧化乙烯(PEO)作为辅助聚合物增加溶液粘性,添加极性溶剂(乙酸、DMF)增加纺丝液的导电性,并且优化光电活性聚合物含量、静电纺丝电压、推注速度等工艺参数,成功制备了以PTB7-V0.05为核、PEO为壳的同轴纳米纤维,经紫外照射纤维内部发生交联固化,再用异丙醇洗涤去除PEO后,得到直径在100 nm以下的具有优异结构稳定性的纯PTB7-V0.05纤维。经验证,该纤维可稳定分散存在于其良溶剂中。在第二部分工作中,我们对PTB7-Vn的光伏性能进行了细致的表征优化,并初步研究了它们的交联性质。实验发现三羟甲基丙烷三(3-巯基丙酸)酯(TTMP)可以显著提高PTB7-Vn体系的紫外交联度,当添加体积比仅为0.01%的TTMP时,PTB7-V0.05在紫外照射30 min下就拥有63.41%的交联度,其器件仍保留了 85%的初始效率值。而且TTMP也可以增加器件的短路电流,基于氯苯、二苯醚和0.01%的TTMP混合溶剂制备的器件效率达到6.78%,电池的稳定性能正在进一步测试当中。在第三部分工作中,我们通过引入烷基侧链来增加BDT-DTBT体系小分子的溶解性,并使用非氯绿色溶剂甲苯来制备器件。研究发现烷基链引入的位置对其光伏性能有着深刻的影响,烷基链位于内侧分子的光伏性能明显优于位于末端的分子。而且基于甲苯溶剂制备的电池效率与氯仿溶剂相当,这对有机太阳能电池的工业化应用有着重大意义。
[Abstract]:Organic solar cells have attracted wide attention due to their advantages of light weight, low price and large area preparation. In organic solar cells, whether the charge can be transmitted efficiently determines the short circuit current density of the cell, and the photoactive polymer nanofibers are often used to establish an efficient charge transfer path because of their extremely high specific surface area. Therefore, the introduction of fiber into the active layer of organic solar cells can improve the photoelectric conversion efficiency of the devices. However, the photoactive polymer fibers have poor solvent resistance and can not be reprocessed in solution, which limits their further development in the field of organic photovoltaic. Based on the technology that electrostatic spinning can facilitate the preparation of core-shell nanofibers, a new strategy for preparing photoactive polymer nanofibers with stable structure and solvent dispersion is proposed. In this strategy, crosslinked photoactive polymers are placed in the nuclear layer of nanofibers and coated with blunt polymers, which are then prepared by internal crosslinking and removal of protective polymers. In the first part of this thesis, we verify this strategy. In this paper, a typical polymer photovoltaic material PTB7 in organic photovoltaic field is selected, and a crosslinked photovoltaic polymer PTB7-Vn is synthesized by introducing terminal bond at the end of some side chains of PTB7. It was found that the thermal, optical and electrochemical properties of the polymer PTB7-V0.05 could not be changed obviously by introducing a certain amount of end double bond into the polymer PTB7, and the crosslinking degree of the polymer PTB7-V0.05 was over 90% after 8 hours of ultraviolet irradiation. Based on this, we began to prepare chemically stable polymer PTB 7-V 0.05 nanofibers. Using single needle electrospinning technology, we added polyethylene oxide (PEO) as auxiliary polymer to the spinning solution to increase the viscosity of the solution, and the polar solvent (DMF) to increase the conductivity of the spinning solution and optimize the content of photoactive polymer. Coaxial nanofibers with PTB7-V0.05 as shell were successfully prepared by electrospinning voltage and injection speed. The fibers were crosslinked and solidified by UV irradiation, and then washed with isopropanol to remove PEO. Pure PTB7-V0.05 fibers with a diameter below 100 nm with excellent structural stability were obtained. It is proved that the fiber can be dispersed stably in the solvent. In the second part, we optimized the photovoltaic properties of PTB7-Vn and studied their crosslinking properties. It was found that the UV crosslinking degree of PTB7-Vn system could be significantly increased by trimethylolpropane tris (TTMP). When the volume ratio of TTMP was only 0.01%, the crosslinking degree of PTB7-V0.05 was 63.41% after 30 min of external irradiation. The device still retains an initial efficiency value of 85%. Furthermore, TTMP can increase the short-circuit current of the device. The device efficiency based on chlorobenzene, diphenyl ether and 0.01% TTMP mixed solvent is 6.78. The stability of the battery is being further tested. In the third part, we introduce alkyl side chains to increase the solubility of small molecules in BDT-DTBT system, and use non-chlorinated green solvent toluene to prepare the devices. It is found that the position of alkyl chain has a profound influence on its photovoltaic performance, and the photovoltaic performance of alkyl chain located inside molecule is obviously superior to that of the molecule located at the end of the alkyl chain. Moreover, the efficiency of the organic solar cells based on toluene solvent is equal to that of chloroform solvent, which is of great significance to the industrial application of organic solar cells.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ340.64;TM914.4

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