Tian Bingchu, Shang Yanbo, Tu Yi, Hu Jun, Han Dong, Xu Qian, Yang Shangfeng, Ye Yifan, Ding Honghe, Li Yu, Zhu Junfa
National Synchrotron Radiation Laboratory, Department of Chemical Physics, University of Science and Technology of China, 230029, Hefei, China.
Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, 230026, Hefei, China.
Chemphyschem. 2023 Oct 17;24(20):e202300400. doi: 10.1002/cphc.202300400. Epub 2023 Aug 10.
The interfacial electronic structure of perovskite layers and transport layers is critical for the performance and stability of perovskite solar cells (PSCs). The device performance of PSCs can generally be improved by adding a slight excess of lead iodide (PbI ) to the precursor solution. However, its underlying working mechanism is controversial. Here, we performed a comprehensive study of the electronic structures at the interface between CH NH PbI and C with and without the modification of PbI using in situ photoemission spectroscopy measurements. The correlation between the interfacial structures and the device performance was explored based on performance and stability tests. We found that there is an interfacial dipole reversal, and the downward band bending is larger at the CH NH PbI /C interface with the modification of PbI as compared to that without PbI . Therefore, PSCs with PbI modification exhibit faster charge carrier transport and slower carrier recombination. Nevertheless, the modification of PbI undermines the device stability due to aggravated iodide migration. Our findings provide a fundamental understanding of the CH NH PbI /C interfacial structure from the perspective of the atomic layer and insight into the double-edged sword effect of PbI as an additive.
钙钛矿层与传输层的界面电子结构对于钙钛矿太阳能电池（PSC）的性能和稳定性至关重要。通过向前驱体溶液中添加少量过量的碘化铅（PbI₂），通常可以提高PSC的器件性能。然而，其潜在的工作机制存在争议。在此，我们使用原位光发射光谱测量对有无PbI₂修饰的CH₃NH₃PbI₃与C之间的界面电子结构进行了全面研究。基于性能和稳定性测试，探索了界面结构与器件性能之间的相关性。我们发现存在界面偶极反转，与未修饰PbI₂的情况相比，修饰PbI₂的CH₃NH₃PbI₃/C界面处的向下能带弯曲更大。因此，修饰PbI₂的PSC表现出更快的电荷载流子传输和更慢的载流子复合。然而，由于碘化物迁移加剧，PbI₂的修饰会破坏器件稳定性。我们的研究结果从原子层的角度对CH₃NH₃PbI₃/C界面结构提供了基本理解，并深入了解了PbI₂作为添加剂的双刃剑效应。
