可热聚合富勒烯/钙钛矿双交联结构的构筑及其在太阳能电池中的应用

How to fabricate efficient and stable perovskite solar cells is one of the key scientific issues in the field of photovoltaics. The defect in the perovskite films is a key factor for limiting the efficiency and stability of the perovskite solar cells. This project devotes to designing and synthesizing thermally polymerizable bis-adduct C60 derivatives with isomer free, and constructing of thermally polymerizable fullerene/perovskite double cross-linked structure in-situ to passivate the grain boundary defects and improve the grain boundary stability of the perovskite, thus increasing the efficiency and stability of the device. Firstly, thermally polymerizable bis-adduct C60 derivatives with isomer free will be synthesized by the steric hindrance of the localization group. Then, we will construct the fullerene/perovskite double cross-linked structure in the mixed-cation/mixed-halide perovskite layer. The influence of the different molecular thermally polymerizable bis-adduct C60 derivatives on the micro-nano structure, carrier transport, device efficiency and stability will be investigated. Finally, the scientific relationship between the molecular structure of the thermally polymerizable fullerenes and the device performance will be established, and thus the efficiency and stability of carbon-based perovskite devices will be improved. This project is proposed to clarify the microscopic mechanism of the thermal polymerization of fullerene derivatives to improve the efficiency and stability of the device, and to provide scientific basis and theoretical support to the further design of functional materials for high performance perovskite solar cells.

如何发展高效稳定的钙钛矿太阳能电池是光伏领域的一个关键科学问题。钙钛矿薄膜中的晶界缺陷是限制其效率和稳定性提升的重要因素。本项目拟设计合成含特殊基团的单一异构体的可热聚合C60二取代衍生物，通过原位构筑可热聚合富勒烯/钙钛矿双交联结构来钝化钙钛矿的晶界缺陷和增加晶界稳定性，进而提高钙钛矿器件的效率和稳定性。首先，利用定位基团的位阻作用合成含特殊基团的单一异构体的可热聚合C60二取代衍生物。然后，以复合钙钛矿为研究体系，研究不同结构的可热聚合C60二取代衍生物构筑的可热聚合富勒烯/钙钛矿双交联结构对钙钛矿薄膜的微纳结构、电荷输运及器件效率和稳定性的影响规律。最后，建立可热聚合富勒烯分子结构与器件性能的科学关系，实现高效稳定的碳基钙钛矿电池器件。项目研究成果可阐明可热聚合富勒烯衍生物提高钙钛矿器件效率和稳定性的微观机制，为进一步设计高性能钙钛矿太阳能电池的功能性材料提供科学依据和理论支撑。

溶液法制备的钙钛矿薄膜通常含有大量的晶界缺陷，这些晶界缺陷是制约钙钛矿太阳能电池效率和工况稳定性提升的关键因素。如何降低钙钛矿薄膜中的晶界缺陷对钙钛矿器件性能的影响是本领域的关键科学问题。本项目致力于探究新型功能化富勒烯材料对钙钛矿薄膜晶界缺陷的调控作用，并通过含特殊官能团的富勒烯衍生物与钙钛矿组成间的化学交联作用，以获得高效率和稳定的钙钛矿光伏器件。取得的主要研究成果如下：（1）研究了不同特殊功能基团与钙钛矿间在加热条件下通过化学相互作用而交联的规律；（2）将不同特殊功能基团引入富勒烯碳笼上，合成了一系列新型富勒烯功能材料，并对其单晶结构、光物理、电化学等性质进行表征；（3）将富勒烯材料引入钙钛矿太阳能电池体系，并通过器件优化，实现了钙钛矿太阳能电池效率大幅度的提升；（4）研究了富勒烯基钙钛矿太阳能电池在工况条件下的失效机制，发现期工况稳定性不仅依赖于钙钛矿成分与富勒烯的交联作用，并发现富勒层的自聚集也是导致其失效的重要原因。项目建立的富勒烯分子结构与器件性能的构效关系对进一步设计应用于高性能钙钛矿器件的富勒烯材料具有重要的参考意义。