高性能染料敏化太阳电池关键有机材料及界面物理化学研究

Owing to the insufficient understanding on multi-channel charge transfer related surface chemistries at the atom and molecule level, the rational correlation between photosensitizer structures and photovoltaic parameters can not be attained in dye-sensitized solar cells (DSCs), leading to the present status that the R&D of new materials for DSCs are mainly by trial and error and the device performance is enhanced in a relatively slow fashion. In view of the national key strategic demand on energy, this project will clarify the microscopic mechanisms of self-assembling of dye molecules on the surface of semiconductor nanocrystals and obtain dense, well-ordered self-assembly monolayer, by means of microscopic structural characterization and modulation of dye molecule organizations on the nanocrystal surface in combination with theoretical calculation and simulation of the titania/dye assemblies. Furthermore, we will employ time-resolved spectroscopic and electrical techniques to detail the complicated interfacial charge transfer kinetics, and clarify the intrinsic mechanisms from dye molecules to micro-/nano-structured assemblies and to interfacial charge transfer dynamics as well as device parameters. On the basis of the aforementioned progress, we will rationally design key organic optoelectronic materials such as exotic outer-sphere redox shuttles and dyestuffs and innovate device structures to realize the positive interaction among the advanced optoelectronic materials, interface physical chemistry and high-performance devices, aiming at a new paradigm of high-performance DSCs.

围绕国家能源重大战略需求，针对目前染料敏化太阳电池中多通道电荷转移动力学相关的原子分子层次的表面化学认识不甚清晰，无法实现染料分子结构和光伏参数之间的理性关联，新材料的开发主要依赖于经验试错法和器件性能提升比较缓慢的状况，本项目拟结合二氧化钛/染料组装体的理论计算及模拟和染料在半导体纳晶表面组装的微观表征，揭示染料分子在半导体纳晶表面的自组装机制，实现染料在半导体纳晶表面的有序、致密、单分子层组装。利用时间分辨光谱和电学测量技术，系统研究复杂界面电荷转移动力学，澄清染料分子结构-组装体微纳特征-电荷转移动力学-器件参数之间的内在关联机制。在此基础上，通过外球电子媒介体和超分子功能染料等关键有机光电材料及器件结构的创新设计，实现先进光电材料-界面物理化学-高性能器件的良性互动，最终实现高性能染料敏化太阳电池的突破。

由染料分子在宽禁带纳晶表面构筑的自组装膜，控制着染料敏化太阳电池的光吸收、电荷分离及电荷复合，影响了在AM1.5G条件下器件所能输出电子的数目和自由能，决定了器件的能量转换效率。长期以来，关于器件中光电功能自组装分子膜微结构和激发态控制的研究鲜有问津。通过项目的实施，我们建立了染料分子自组装膜厚度、质量密度的测量方法，改善了电荷提取/光电压衰减测试系统的时间分辨率（10ns），提高了纳秒瞬态吸收光谱测试系统的灵敏度（10微OD），实现了太阳电池器件的近红外（770nm-1400nm）超快发光的高灵敏测量，为新型太阳电池界面微结构、激发态物理、电荷传递动力学的研究提供了有力的研究手段。揭示了染料分子结构、染色溶剂等关键元件依赖的激发态、多通道电荷转移动力学规律及其微观起源。借鉴量子阱的概念，提出了缺陷修复的“宽能隙分子填充”方法，大幅度衰减了半导体/电解质界面的表观电荷复合速率常数。探索出一套适合长程电子离域染料的基态/激发态结构优化、光电性质预测的基组与泛函。以较精确的材料计算为基础，设计并制备出系列具有自主知识产权的非氰基丙烯酸染料、苝基多环芳烃染料和蒽基多环芳烃染料，在激发态控制、高效器件、高热稳定器件和蓝色电池方面取得重要进展。该项目的执行进一步巩固了中国在染料敏化太阳电池领域的国际先进地位。获5个授权中国发明专利，申请中国发明专利12项，申请美国专利2项，发表SCI论文48篇（IF>3的45篇，IF>7的28篇），相关研究被Chemical & Engineering News等多次正面评述。