【作者】 高瑞；

【导师】 王立铎；

【作者基本信息】 清华大学 ， 化学， 2013， 博士

【摘要】 染料敏化太阳能电池（Dye-sensitized solar cells，简称DSCs）是清洁能源领域中备受关注的研究方向，界面修饰和复合敏化是DSCs研究中的重要课题。本论文针对DSCs中光阳极/染料/电解质界面处染料的团聚、染料和光阳极的能级匹配、电子注入与电子反向复合、界面电子过程等关键科学问题，开展了染料吸附后的界面修饰及其光伏特性的研究；以界面修饰材料为载体层组装了交替多层结构，研究了交替多层结构复合敏化及其界面电子过程等。主要研究成果如下：（1）研究了染料吸附后的界面修饰材料和方法。将4-叔丁基吡啶（TBP）用于染料吸附后的界面修饰，而不是添加到电解质中。TBP的界面修饰削弱了染料的团聚，抑制了电荷复合，同时避免了其对电解质中电荷传输的阻挡作用，改善了电池的转换效率。但TBP与染料分子之间的相互作用会降低染料的LUMO能级，导致电子注入效率下降，从而降低短路电流。（2）首次把醋酸镁（Mg（OAc）₂）用作界面修饰材料，研究了染料吸附后Mg（OAc）₂的界面修饰及其光伏特性。红外光谱及循环伏安结果表明Mg（OAc）₂与N3染料分子之间的相互作用削弱了染料团聚，阻挡了电荷复合，同时提高了N3分子的LUMO能级，从而提升了电子注入效率。Mg（OAc）₂界面修饰有效改善了DSCs的光电转换效率和稳定性。（3）在TBP和Mg（OAc）₂等修饰材料研究基础上，把多功能修饰材料8-羟基喹啉铝（Alq₃）用于染料吸附后的界面修饰，研究结果表明，Alq₃的界面修饰阻挡了电荷复合。同时，Alq₃和N3染料之间的福斯特共振能量转移（F rster resonance energytransfer, FRET）增加了电池光响应。（4）研究了交替多层结构复合敏化及其光伏特性。利用TiO₂平整膜简化模型，研究了适用于交替多层结构的载体材料的性质；组装了N3/Al₂O₃/N3交替多层结构，该结构能有效提高光吸收，阻挡暗反应，改善界面电子传输，从而提高电池效率；组装了N3/Al₂O₃/N749交替多层结构，该结构有效拓宽了电池光响应范围，同时降低暗电流，进而提高了电池的转换效率。基于交流阻抗的结果建立了等效电路模型，利用该模型对界面电子过程模拟得到的数据和实验测量值相吻合，从理论上解释了交替多层结构对界面阻抗特性以及电子注入与复合等过程的影响。更多还原

【Abstract】 Dye-sensitized solar cells （DSCs） is an important research field of clean energysources. Inerface modification and composite sensitization are important approaches toimprove the performance of DSCs. In this paper, to solve some key problems such asdye aggregation, energy level matching between dye and photoanode, electron injectionand recombination at the interface of photoanode/dye/electrolyte, we mainly researchedinterface modification after dye-adsorption. Furthermore, using interface modificationmaterials as interlayer, alternating assembled structure for composite sensitization wasfabricated. The research is focused on the interaction between interface modificationmaterials and dye molecules and their effects on the photovoltaic properties of DSCs.The main results and conclusions of this dissertation are as follows:（1） The materials and methods for interface modification after dye-adsorption havebeen investigated. We used TBP for interface modification after dye-adsorption, insteadof adding it in the electrolyte as usual. It can be seen in the FTIR that TBP retarded thedye aggregation. Results of EIS indicated that TBP could reduce the chargerecombination. Furthermore, using TBP for interface modification could strengthenedthe effect of reducing charge recombination and avoid the disadvantage of blockingcharge diffusion in the electrolyte at the same time. As a result, a higher enhancement ofDSCs’ conversion efficiency by using TBP for interface modification afterdye-adsorption has been obtained. However, the interaction between TBP and N3dyemolecules decreased the LUMO of N3, resulting in the decrease of electron injectionefficiency, which could cause the reducing of photocurrent.（2） We studied the effects of Mg（OAc）₂inferface modification after dye-adsorptionfor the first time. Results of FTIR and CV represented that interaction betweenMg（OAc）₂and N3dye could retard the dye aggregation and charge recombination.Furthermore, the interaction also shifted the LUMO of N3to a higher level, whichenhanced the electron injection efficiency. As a result, Mg（OAc）₂inferface modificationafter dye-adsorption remarkably improved the efficiency and stability of DSCs.（3） As the interface modification materials of Mg（OAc）₂and TBP improve theperformance of DSCs through only retarding the dye aggregation and charge recombination, a multifunction interface modification material,8-hydroxyquinolinealuminium （Alq₃） has been developed and applied in the interface modification afterdye-adsorption. Fisrtly, it retarded the charge recombination, shown in the EIS and darkcurrent curve. Secondly, it transferred energy to N3dye through F rster resonanceenergy transfer （FRET）, enhancing the photo-resoponse of DSCs.（4） The interlayer of alternating assembled structure has been studied using acompact TiO₂film as a simplified model for the TiO₂porous film. Based on Al₂O₃interlayer, N3/Al₂O₃/N3alternating structure has been fabricated. This structureincreased light absorption, improved the interface charge transfer, retarded thecharge recombination and then enhanced the conversion efficiency. To furtherwiden photoresponse range, the N3/Al₂O₃/N749alternating assemble structure hasbeen fabricated. Compared to the devices using individual dye, such structure increasedthe conversion efficiency and reduced the charge recombination. Based on results ofEIS, a series of equivalent circuit models were built to explain electron process and thechange of parameters of DSCs. The value of impedance elements obtained bycalculation from the equivalent circuit models accorded with the measured values well.更多还原