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Studies of Conjugated Small Molecules, Polymers and Organic-Inorganic Hybrid Materials for Photovoltaic Applications.

机译：用于光伏应用的共轭小分子，聚合物和有机-无机杂化材料的研究。

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This dissertation focuses on the photophysical properties and device studies of three different types of materials, namely polyoxometalate (POM)-containing organic-inorganic hybrids, near-IR absorbing conjugated polymers and discotic polycyclic aromatic hydrocarbons. POM-containing organic-inorganic hybrids are interesting because of the potential roles, such as electron acceptors and electron transporters, that POM clusters may be able to play. A molecular hybrid (Mo6-Fe) containing a hexamolybdate cluster on one end, a ferrocenyl unit on the other and a conjugated bridge has been explored for photovoltaic applications. This hybrid shows direct charge transfer absorption in its UV-vis absorption spectrum. While the hybrid itself show very poor photovoltaic properties, solar cells fabricated from its PCBM blends show attractive device performance with power conversion efficiencies up to 1.8%. To develop a POM-containing hybrid system that exhibits the desired morphologies for solar cells, three POM-containing rod-coil hybrid diblock copolymers (PS-Mo6-PT1-3) with different rod block lengths have been carefully studies on their optical, electrochemical, morphological and photovoltaic properties. Solar cells fabricated from these hybrid diblock copolymers (without added PCBM) did show photovoltaic effects with around 0.01% power conversion efficiency. While good open circuit voltage (1.25 V) is observed for the pristine film, the short circuit photocurrent is dismally low. Annealing improves the photocurrent by one order of magnitude and also the fill factor, presumably due to the formation of desired phase-separated domains. The overall photocurrent is still very low, likely due to the poor photoinduced charge transfer from the PT backbone to the POM cluster, which is corroborated by femtosecond time-resolved fluorescence studies. Two new POM-containing main-chain conjugated polymers (P10 and P11) have been synthesized and characterized in detail. Simple single layer solar cells based on P10 show respectable power conversion efficiencies up to 0.31%. Incident photo-to-current conversion efficiency measurements have confirmed the photocurrent contribution of both the organic pi-segments and the POM clusters.;Near infrared (NIR) absorbing conjugated polymers combining alkoxy-substituted bithiophene units with different comonomers have been synthesized. Due to the electron-donating properties of the alkoxy substituents and the near planar structure of the bithiophene unit, conjugated polymers containing 3,3'-dialkoxy bithiophene units show strong propensity towards electrophiles such as H +. The protonated polymers show strong NIR absorptions due to intra-chain charge transfer. The strength and the wavelengths of the NIR absorption depend on the comonomers as well. Comonomers with stronger electron donating properties (such as NDT over INDT) lead to more intense NIR absorptions and longer NIR absorption wavelengths. The protonation process is found to follow the first order reaction kinetics. While the NIR-absorbing polymers, when blended with PC71BM, show photovoltaic properties, only the absorptions in the UV-visible range are able to produce photocurrent.;Three PAH molecules, all based on the TBP core but with different peripheral substituents, have been studied as hole transporting materials. The SCLC hole mobility of compounds 1a-1c pristine films deposited by spin-coating were measured to be 8.58x10-4 cm2 V -1 s-1, 5.42x10-3 cm2 V-1 s-1, and 2.30x10-4 cm2 V-1 s-1, respectively, which are typical for solution-processed organic thin films. Thermal annealing improved the mobility of all three compounds with compound 1b showing the largest increase and an appealing SCLC hole mobility of 3.63x10 -2 cm2 V-1 s-1 was obtained. The XRD studies of thin films before and after annealing suggest better molecule orders for both 1a and 1b after thermal annealing, which is likely responsible for their improved hole mobility.
机译：本文主要研究三种不同类型材料的光物理性质和器件研究，即含多金属氧酸盐（POM）的有机-无机杂化材料，近红外吸收共轭聚合物和盘状多环芳烃。包含POM的有机-无机杂化体很有趣，因为POM簇可能具有潜在的作用，例如电子受体和电子转运体。已开发出一种分子杂化物（Mo6-Fe），其一端包含六钼酸盐簇，另一端包含二茂铁单元，并具有共轭桥，可用于光伏应用。该杂化物在其UV-vis吸收光谱中显示出直接的电荷转移吸收。尽管混合动力汽车本身显示出非常差的光伏性能，但由其PCBM混合物制成的太阳能电池仍具有诱人的设备性能，功率转换效率高达1.8％。为了开发展现出所需形状的太阳能电池的含POM的杂化系统，已对三种具有不同棒嵌段长度的含POM的棒-线圈杂化二嵌段共聚物（PS-Mo6-PT1-3）进行了仔细的光学，电化学研究。 ，形态和光伏特性。由这些杂化二嵌段共聚物（不添加PCBM）制成的太阳能电池确实显示出光伏效应，功率转换效率约为0.01％。在原始膜上观察到良好的开路电压（1.25 V）时，短路光电流极低。退火可以将光电流提高一个数量级，并且还可以将填充因子提高一个，这大概是由于形成了所需的相分离域所致。总的光电流仍然非常低，这可能是由于从PT骨架到POM团簇的光诱导电荷转移不佳所致，而飞秒时间分辨荧光研究证实了这一点。合成了两种新型的含POM的主链共轭聚合物（P10和P11），并对其进行了详细表征。基于P10的简单单层太阳能电池的功率转换效率高达0.31％。入射光电流转换效率的测量结果已经证实了有机pi段和POM簇的光电流贡献。合成了烷氧基取代的联噻吩单元与不同共聚单体相结合的近红外（NIR）吸收共轭聚合物。由于烷氧基取代基的供电子特性和联噻吩单元的近平面结构，含有3,3'-二烷氧基联噻吩单元的共轭聚合物显示出对亲电子体（如H +）的强烈倾向。由于链内电荷转移，质子化的聚合物显示出强大的近红外吸收。 NIR吸收的强度和波长也取决于共聚单体。具有更强电子给体性质的共聚单体（例如，在INDT上的NDT）导致更强的NIR吸收和更长的NIR吸收波长。发现质子化过程遵循一级反应动力学。虽然吸收NIR的聚合物与PC71BM混合后具有光伏性能，但只有在UV可见光范围内的吸收才能够产生光电流。；三个PAH分子均基于TBP核，但具有不同的外围取代基作为空穴传输材料而被研究。通过旋涂沉积的化合物1a-1c原始膜的SCLC空穴迁移率测量为8.58x10-4 cm2 V -1 s-1、5.42x10-3 cm2 V-1 s-1和2.30x10-4 cm2 V-1 s-1分别是溶液处理的有机薄膜的典型特征。热退火改善了所有三种化合物的迁移率，其中化合物1b表现出最大的增加，并且获得了吸引人的SCLC空穴迁移率3.63x10 -2 cm2 V-1 s-1。退火前后薄膜的XRD研究表明，热退火后1a和1b的分子序更好，这可能是其空穴迁移率提高的原因。

著录项

  • 作者

    Jin, Lu.;

  • 作者单位

    University of Missouri - Kansas City.;

  • 授予单位 University of Missouri - Kansas City.;
  • 学科 Chemistry.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 201 p.
  • 总页数 201
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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