【作者】 郭福领；

【导师】 花建丽；

【作者基本信息】 华东理工大学 ， 应用化学， 2013， 博士

【摘要】 对于新一代的太阳能电池：染料敏化太阳能电池(DSSCs)由于其相对较低的制备成本,在世界范围内引起了广泛关注。在电池的组成部分中,Ti02光阳极和光敏染料作为电池捕获太阳光和完成电子传输的关键部分发挥着重要的作用。本文改善了TiO2光阳极的制备方法,并且对光阳极进行修饰；同时合成了一系列D-π-A-π-D型和D-A-π-A型染料,研究了染料结构对电池转换效率的影响,并对电池器件性能进行了优化。第一章：简要介绍了现阶段染料敏化太阳能各组成部分光阳极、光敏染料,电解质和对电极的研究进展,并且在此基础上,提出本课题的主要研究内容和意义。第二章：在以硫酸钛为前驱体制备浆料的过程中,加入葡萄糖,控制纳米颗粒的生长,得到了一维结构的纳米棒状二氧化钛,长约150nm,直径约为31.60nm。一维棒状结构的纳米晶二氧化钛具有较高的电子传输性能,提高了从激发态注入二氧化钛导带的电子传输到外电路的速率,降低了电子回传和复合的几率,使其电池的开路电压达到848mV,光电转换效率高达8.57%;在以钛酸异丙酯作为钛前驱体的浆料制备过程中,加入乙基纤维素抑制二氧化钛纳米颗粒尺寸的增长,成功得到了更小粒径的纳米二氧化钛颗粒(粒径从36.72nm减小到15.75nm),基于N719染料电池的短路电流从14.61增加到18.05mA/cm2,光电转换效率从7.86%提高到9.59%,提高了22%。第三章：为了丰富吡咯并吡咯二酮(DPP)类染料在染料敏化太阳能电池中的应用研究,设计合成了两个以三苯胺和N,N-二(4-甲氧基苯基)苯胺为给体,DPP单元为共轭桥,羧酸基团作为电子受体的D-π-A-π-D型纯有机染料DPP-I和DPP-Ⅱ.分别测试了两种染料的光物理和电化学性能。电化学测定的数据表明,给体的改变能够有效调节染料的HOMO和LUMO能级,调节染料的电子注入和染料再生的驱动力。基于染料DPP-Ⅰ的染料敏化太阳能电池表现更好的光伏性能：最高单色光入射光电流转换效率(IPCE)达到了80.6%,总的转换效率为2.68%。而在相同的条件下,染料DPP-Ⅱ的电池效率仅为0.51%。在以共吸附剂CDCA优化后,DPP-Ⅱ的效率提高到了1.37%。第四章：为了降低二氧化钛光阳极中电子回传和复合的几率,采用连续离子层吸收和反应法(SILAR)将CuInS2量子点层沉积在二氧化钛薄膜表面,修饰光阳极。然后将两个联噻唑为π-共轭桥的染料(BT-C1和BT-C2)敏化到含有CuInS2量子点的Ti02膜上形成染料/CuInS2/TiO2型光阳极。实验结果表明：CuInS2能垒层不仅可以有效地改善电池的开路电压(Voc),而且能略微提高短路光电流(Jsc)。而传统ZnO能垒层在提高开路电压的同时,却明显减少Jsc。交流阻抗谱(EIS)测试进一步证实了CuInS2在光阳极表面形成了抑制注入电子和电解质中离子复合的能垒层,提高电池的开路电压。在AM1.5(100mW cm-2)光强条件下,基于BT-C1和BT-C2敏化的光阳极在以CuInS2,为能垒层的电池中开路电压增加了22和27mV,电池总的转换效率达到7.20%和6.74%。第五章：设计合成了三种分别以咔唑,三苯胺和吲哚啉为电子给体的联噻唑D-A-π-A型有机染料(BT-T1-T3),研究了给体对染料敏化电池光伏性能的影响,紫外-可见吸收光谱表明,以吲哚啉为给体的染料BT-T3吸收光谱明显红移,其吸收的截止波长扩展到近700nm。同时BT-T3具有最宽的IPCE谱图响应范围,并且在580-650nm范围内保持高于BT-T1和BT-T2的IPCE谱图10-15%的数值。电化学测量数据表明,电子给体对染料分子的HOMO和LUMO能级具有影响。在AM1.5(100mWcm-2)光强条件下,基于吲哚啉为给体的BT-T3染料电池得到了最高转换效率7.86%(短路电流为15.26mA/cm2,开路电压为747mV,填充因子为0.69)。第六章：噻吩作为π共轭桥链引入到染料敏化剂中,能够拓展染料的吸收光谱,提高染料的摩尔消光系数。针对三苯胺和吲哚啉为给体的染料BT-T2和BT-T3,在给体和联噻唑之间引入噻吩单元合成了染料TBT-T2和TBT-T3。在三苯胺为给体的染料中,引入噻吩后,染料的最大吸收波长和吸收截止波长都出现红移,染料摩尔消光系数提高。TBT-T2染料敏化电池的效率从7.12%提高到7.51%;有趣的是在以吲哚啉为给体的染料BT-T3中引入噻吩,染料的吸收光谱蓝移,染料分子内的电荷转移受阻,激发态染料的电荷分离效率降低,造成染料TBT-T3敏化电池的短路电流明显降低,从14.77mA/cm2降低到4.52mA/cm2,电池的效率也从7.86%减少到1.93%。更多还原

【Abstract】 As a new generation of solar cells, the dye-sensitized solar cells (DSSCs) have attracted widespread concern in the world due to its relatively low cost of preparation. The photoanodes and sensitizers play an important role as the key part of capturing sun ligh and transporting electron in DSSCs. In this paper, modification and optimization of the photoanodes were studied. And a series of D-π-A-π-D-and D-A-π-A type sensitizers with diketopyrrolopyrrole and bithiazole core were synthesized and their photovoltaic performances have been investigated in detail.In chapter1, the definition of the structure and principle for the dye-sensitized solar cells, electrolytes and counter electrode are introduced. Recent researches of nanoporous semiconductor electrode and new dye-sensitizers have been reviewed. Then the research strategy of the dissertation is presented on that basis.In chapter2, in the process of titanium sulfate as the precursor, the glucose was added to control the growth of particles to obtain a one-dimensional structure of nano-rod-shaped titanium oxide which was about150nm lengths and31.60nm diameters. The one-dimensional rod-like structure of titanium dioxide has higher electron transmission efficiency and improves the rate of electron transmission to the external circuit. Electrons from the excited dye were injected into the conduction band of titanium dioxide can reduce the probability of electron recombination. Finally, the cell performaned an improving open circuit voltage of848mV and overall conversion efficiency reached8.57%. Ethyl cellulose was added in the process of Titanium (IV) Isopropoxide as the titanium precursor to control the size of titanium dioxide nano-particle size. A smaller particle size of titanium dioxide was obtained (Particle size decreased from36.72nm to15.75nm) successfully. The short-circuit current for DSSCs based on N719was increased from14.61to18.05mA/cm2, and an overall conversion efficiency was up to9.59%.In chapter3, two new metal-free organic dyes (DPP-Ⅰ and DPP-Ⅱ) with diketopyrrolopyrrole (DPP) core were designed and synthesized to enrich the application of DPP unit in DSSCs, in which triphenylamine or N,N-bis(4-methoxyphenyl)benzenamine moieties was used as the electron donor, DPP units as theπ-conjugated bridge, and carboxylic acid group as the electron acceptor. Photophysical and electrochemical properties of two dyes were investigated by UV-vis spectrometry and cyclic voltammetry. Electrochemical measurement data indicate that the tuning of the HOMO and LUMO energy levels can be conveniently accomplished by alternating the donor moiety. The DSSC based on dye DPP-I showed better photovoltaic performance:a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of80.6%corresponding to an overall conversion efficiency of2.68%. Although the power conversion efficiencies are not so high, this work explores new donor-π-accepter-π-donor models and the effects of molecular design on optical propertiesIn chapter4, the quantum dot CuInS2layer was deposited on TiO2film using successive ionic layer absorption and reaction (SILAR) method, then two bithiazole-bridged dyes (BT-C1and BT-C2) were sensitized on the CuInS2films to form dye/CuInS2/TiO2photoanodes for DSSCs. It was found that the quantum dots CuInS2as an energy barrier layer can improve the solar cell open-circuit voltage (Voc) effectively. Moreover, the CuInS2barrier layer can also increase short-circuit photocurrent (Jsc) compared to the large decrease in Jsc with ZnO as energy barrier layer. The electrochemical impedance spectroscopy (EIS) measurement showed that the CuInS2formed a barrier layer to suppress the recombination from injection electron to the electrolyte and improve Voc. Finally, the Voc increased about22and27mV for CuInS2coating TiO2-based BT-C1and BT-C2-sensitized cells, the overall conversion efficiencies also reached to7.20%and6.74%, respectively.In chapter5, three metal-free bithiazole organic dyes (BT-T1～T3) based on D-A-π-A building blocks were designed and synthesized for dye-sensitized solar cells (DSSCs) to study the influence of different electron donors on photovoltaic properties, in which the electron donors of BT-T1～T3were carbazole, triphenylamine and indoline moieties, respectively. The UV/Vis absorption spectra showed that BT-T3containing indoline as electron-donor displayed red-shift absorption compared to the other two dyes and the most broadened spectrum was an onset close to700nm.n And the IPCE spectra of BT-T3were also broadened and kept higher IPCE value during580-650nm. Electrochemical measurement data indicated that the HOMO and LUMO energy levels could be tuned through introducing different electron-donor in the dye molecular. It was found that the overall conversion efficiency of indoline donor based dye BT-T3showed the highest efficiency of7.86%under AM1.5irradiation (100mW/cm2). The electron lifetime calculated from electrochemical impedance spectroscopy (EIS) measurements demonstrated the reduced charge recombination and the higher open-circuit voltageIn chapter6, thiophene as the π-conjugated bridge chain could expand the absorption spectrum and improve the molar extinction coefficient of the dye when it was introduced into the dye sensitizers. Thiophene was introduced into the dyes molecular (BT-T2with triphenylamine as donor, BT-T3with indoline as donor) between donor and bithiazole to afford TBT-T2and TBT-T3. For the dyes with triphenylamine, the introduction of thiophene afforded a red-shift maximum absorption and threshold wavelength and improved molar extinction coefficient. The dye-sensitized cell efficiency increased from7.12%to7.51%. While the experimental and the theoretical density functional calculation result indicated that the introduction of thiophene in the indoline dye leaded to a blue shift absorption spectra. The intramolecular charge transmission was blocked. The decreased rate of charge separation efficiency caused the short-circuit current of TBT-T3sensitized solar cell reduced significantly, from14.77mA/cm2to4.52mA/cm2. And the efficiency also reduced from7.86%to1.93%.更多还原