优化有源层形貌提高有机太阳能电池性能的研究

发布时间：2018-01-02 23:30

本文关键词：优化有源层形貌提高有机太阳能电池性能的研究　出处：《北京交通大学》2017年博士论文　论文类型：学位论文

【摘要】：近年来,有机太阳能电池得到快速发展。但是与传统无机太阳能电池相比,有机太阳能电池的光电转换效率和稳定性仍然较低,还达不到产业化的要求。不仅有机太阳能电池的性能有待提高,其复杂的工作机理也需要进一步研究。本论文以制备高效率高稳定性的有机太阳能电池为核心目标,以优化有源层形貌为研究重点,以采用不同分子结构的受体、优化有源层自组装过程和开发有效的后处理工艺为切入点,以薄膜形貌表征技术、光学与光谱学表征技术、电学表征技术、表面成分表征技术为支撑点,以探索优化有源层形貌提高器件性能的关键科学问题为落脚点。主要研究内容如下:(1)通过研究不同分子结构的受体对给受体分子排布方式的影响,探索给受体分子排布方式对有机太阳能电池性能的影响机理。以SMPV1:PC71BM和SMPV1:ICBA为有源层的有机太阳能电池的光电转换效率分别为7.05%和2.54%。以ICBA为受体的器件短路电流远低于以PC71BM为受体的器件短路电流,主要原因有以下两点:(ⅰ)ICBA在可见光范围内吸光能力低于PC71BM;(ⅱ)SMPV1和ICBA分子间垂直交叉的分子排布方式会限制激子的解离、电荷的传输和收集。通过给体和受体的分子结构调控给受体分子排布方式,为提高有机太阳能电池的性能提供了一种新途径。(2)利用醇溶液调控有源层自组装时间,探索有源层在自组装过程中给受体分子排布的变化趋势。在有源层上表面旋涂PFN甲醇溶液的方法既可以快速地终止有源层自组装过程,又可以制备PFN界面修饰层。有源层(PffBT4T-20D:PC71BM)的自组装时间以20分钟为间隔从20分钟被调整到120分钟。经过80分钟的有源层自组装和PFN界面修饰层的添加,有机太阳能电池的光电转换效率从6.74%提高到8.66%。研究表明有源层在自组装过程中有两个变化趋势:(ⅰ)给体分子排布方式逐渐从edge-on向face-on转变,有利于空穴的传输;(ⅱ)给受体相分离尺度逐渐地增加,过长时间的有源层自组装会导致过大的给受体相分离尺度,不利于激子的解离。有源层自组装时间对给体分子排布方式和给受体相分离的优化起到关键的作用,调控有源层的自组装时间是非常有必要的。在有源层上表面旋涂醇溶液是调控有源层自组装时间的有效策略。(3)采用倒置的有源层干燥方法调控有源层自组装过程,优化给体分子排布的有序性以及给受体垂直结构相分离程度。采用倒置的有源层干燥方法明显地提高了基于四种不同有源层(PTB7-Th:PC71BM、PTB7:PC71BM、PffBT4T-20D:PC71BM和PBDT-TS1:PC71BM)的有机太阳能电池的效率和稳定性。采用倒置的有源层干燥方法提高有机太阳能电池性能的原因可归纳为以下三点:(ⅰ)提高了给体分子π-π堆积的有序性及紧密性,有利于空穴传输;(ⅱ)优化了给受体垂直结构相分离,有利于电荷的传输和收集;(ⅲ)使PC71BM更稳固地分布在更有序及更紧密的给体网络中,提高了器件的稳定性。通过稳定性测试研究表明封口膜封装方法可以有效地阻挡水和氧向器件内部扩散,提高有机太阳能电池的稳定性。(4)利用甲醇和溶剂添加剂的互溶特性,采用甲醇或PFN甲醇溶液浸润有源层优化给受体垂直结构相分离。在溶剂添加剂DIO和甲醇的挥发过程中,PC71BM分子会向有源层的上表面迁移,通过调控甲醇浸润时间可以精细地调控给受体垂直结构相分离程度。采用PFN甲醇溶液浸润有源层的方法,不仅可以形成PFN界面偶极增加穿过有源层的内建电场,还可以利用甲醇优化给受体垂直结构相分离。采用先甲醇浸润有源层后旋涂PFN甲醇溶液的两步法策略,既可以优化有源层中给受体垂直结构相分离又可以获得超薄的PFN界面偶极层,为提高有机太阳能电池性能提供了简单有效的方法。先调控有源层自组装时间后采用两步法策略可以先优化给体分子排布方式,再调控受体分子再分布,最后获得超薄的PFN界面偶极层。这种逐步的优化策略通过协同地优化有源层自组装时间和甲醇浸润时间可以进一步提高有机太阳能电池的光电转换效率。
[Abstract]:In recent years, organic solar cells have a rapid development. But compared with the traditional inorganic solar cells, photoelectric conversion efficiency and stability of organic solar cells is still low, has not yet reached the requirement of industrialization. Not only the performance of the organic solar cell needs to be improved, the working mechanism of the complex also need further research. The organic solar cell based on the preparation of high efficiency and high stability is the core goal, to optimize the morphology of the active layer is the focus of the study, using different receptor molecule structure, optimization of the active layer self-assembly process and the development of effective postprocessing technology as the starting point, the film morphology characterization techniques, optical and spectroscopic characterization techniques, electrical characterization techniques, surface composition characterization techniques for the support, in order to explore the optimization of active layer morphology to improve key scientific problems in device performance as the foothold. The main contents are as follows: (1). The effect of different molecular structure of the receptor to receptor molecular arrangement, to explore the molecular arrangement of receptor effects on the performance of organic solar cells. The mechanism of the photoelectric conversion efficiency of organic solar cell active layer with SMPV1:PC71BM and SMPV1:ICBA were 7.05% and 2.54%. with ICBA as the short-circuit current is far lower than that of PC71BM receptor the short-circuit current of the receptor, there are two main reasons: (I) ICBA in the range of visible light absorption ability is lower than PC71BM; (II) the dissociation of the vertical cross way molecular arrangement SMPV1 and ICBA molecules will limit the exciton, charge transfer and collection. The molecular structure of the regulation of donor and acceptor donor acceptor the molecular arrangement, which provides a new way to improve the performance of organic solar cells. (2) the use of alcohol solution control active layer self-assembly time, explore the active layer in group The change trend of receptor molecules arranged to process. In the method of surface active layer spin coated PFN methanol solution can be quickly terminated active layer self-assembly process, and the preparation of PFN interface modification layer. The active layer (PffBT4T-20D:PC71BM) self-assembly time on a 20 minute interval from 20 minutes to be adjusted 120 minutes. After 80 minutes of active layer self-assembly and PFN interface modification layer, the photoelectric conversion efficiency of organic solar cells increased from 6.74% to 8.66%. of the active layer in the self-assembly process has two trends: (I) to split sub arrangement gradually from edge-on to face-on transformation, transmission for hole; (II) to the receptor separation scale gradually increased, the active layer long self-assembly leads to excessive phase separation to the receptor scale, is not conducive to the exciton dissociation. Active layer self-assembly time to split Optimal arrangement and phase separation of the receptor to play a key role in self-assembly time regulation of the active layer is very necessary. In the active layer on the surface of the alcohol solution is regulation of spin coated active layer self-assembly time effective strategies. (3) using inverted active layer drying method of active layer self control the assembly process, in order to optimize the body and to the receptor molecular arrangement of the vertical structure of the degree of phase separation. The inversion of the active layer drying method is obviously improved based on four different active layer (PTB7-Th:PC71BM, PTB7:PC71BM, PffBT4T-20D:PC71BM and PBDT-TS1: PC71BM) efficiency and stability of organic solar cell. The inversion of the active layer drying method to improve because the performance of the organic solar cell can be summarized as the following three points: (I) to improve the orderly molecular stacking and close, in favor of hole transport; (II) optimization The vertical structure of phase separation to the receptor, which is beneficial to the charge transfer and collection; (III) to make PC71BM more firmly in the distribution of more orderly and more closely to the network, improve the stability of the device. Through the test of stability showed that sealing film packaging method can effectively prevent water and oxygen diffusion to internal devices, improve the stability of organic solar cells. (4) solubility characteristics using methanol and solvent additive, infiltration of the active layer to optimize the vertical structure of receptor phase separation by using methanol or methanol solution of PFN. In the process of solvent volatile additive DIO and methanol, PC71BM molecules to the surface migration of the active layer, can be finely tuned to the receptor the vertical structure of the degree of phase separation through the regulation of methanol infiltration time. Using PFN methanol solution method of infiltration of the active layer, not only can increase through the formation of PFN interfacial dipole in the active layer of the built-in electric field also Can optimize the utilization of methanol to the receptor vertical structure of phase separation. Two step strategy using methanol infiltration active layer was spin coated PFN methanol solution, which can optimize the active layer to the receptor vertical structure phase separation and can obtain PFN interface thin, in order to improve the performance of organic solar cell provides a simple and effective method. The first regulation of active layer self-assembly time after the two step strategy can give first optimization molecular arrangement, and regulation of the receptor molecular distribution, finally obtained the PFN interfacial dipole layer thin. This gradual optimization strategy with the optimization of the active layer self-assembly time and methanol soaking time can further improve the photoelectric conversion efficiency of organic solar cells through the association.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM914.4

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