在新型钙钛矿（AMX3）结构中，A位离子负面迁移诱导的[MX6]4-八面体骨架不可逆畸变是诱导三维（3D）钙钛矿结构不稳定的根源。本项目基于材料-结构-性能的构效关系，围绕钙钛矿薄膜不可逆分解的形成机制和对电池稳定性的影响机制及解决方案展开，设计和培养一系列A位取代基团诱导的新型低维（LD）钙钛矿单晶，从维度可调的LD钙钛矿单晶（2D，1D和0D）微结构入手，通过进一步深入研究LD-3D钙钛矿薄膜异质结区结晶成核和生长的热力学问题和动力学过程，原位制备维度可调LD-3D异质结钙钛矿薄膜及太阳电池。在此基础上，通过调控异质结区晶体形成能和缺陷形成能，封锁离子负面迁移通道，钝化缺陷态等途径从根本上解决钙钛矿薄膜的稳定性问题。同时，建立一系列基于超快激光光谱技术的原位、实时、动态表征技术，通过系统研究电池器件的光、热和湿度稳定性，最终获得转换效率达20%以上且长期稳定的LD-3D钙钛矿太阳电池。

In the new type of perovskite (AMX3) structure, the irreversible distortion of the [MX6]4- octahedral framework induced by the negative migration of A-site ions would result in the structural instability of 3-dimensional (3D) perovskites. This project, based on the relationship of material-structure-function, aims to elucidate the formation mechanism of irreversible decomposition of perovskite film and provide the solution to tackle the stability issue of perovskite solar cells. A series of novel low-dimensional (LD) perovskite single crystals will be designed and prepared by means of partial/whole substitution of A-site groups. By further studying the thermodynamics and kinetics of nucleation and crystallization in the LD-3D perovskite heterojunction in terms of the single crystal structure of LD perovskites with tunable dimension (2D, 1D and 0D), we will in-situ prepare LD-3D hybrid perovskite thin films and solar cells. Accordingly, the stability of perovskite thin films is expected to be intrinsically solved by regulating the crystal formation energy and defect formation energy in the heterojunction domain, blocking the negative ion-migration channels and passivating the defect states. Likewise, a series of in-situ, simultaneous, and dynamic characterization techniques based on ultra-fast laser spectroscopy are established. The light, heat and humidity-dependent stability of the LD-3D perovskite solar cells will be systematically studied. Consequently, the stable LD-3D perovskite solar cells with more than 20% power conversion efficiency are obtained.