Zhang Siyu, Su Jie, Zhang Jincheng, Lin Zhenhua, Yuan Haidong, Chang Jingjing, Hao Yue
State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, Shaanxi Joint Key Laboratory of Graphene, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an 710071, China.
J Phys Chem Lett. 2021 Dec 16;12(49):11834-11842. doi: 10.1021/acs.jpclett.1c03565. Epub 2021 Dec 6.
Using density functional theory combined with molecular dynamics, we comprehensively investigated the performance enhancement mechanism of the device after surface reconstruction by passivating different halogen groups (, F or Cl) at the ETL/perovskite interface. We demonstrated that the halogen group at the ETL layer could stabilize the geometric structure of the perovskite surface by balancing the interfacial interaction, ionic migration, and lead iodide framework. Even though halogen passivation decreased and increased the interface charge transfer at the O- and SnO-terminated MAPbI/SnO interfaces, respectively, halogen passivation optimized surface reconstruction and could theoretically relieve the interface carrier recombination according to the changes in conduction band offsets generated by halogen passivation. Furthermore, the interfacial carrier recombination of the MAPbI/SnO interface was also connected to the interfacial gap states, which were smaller for O-terminated MAPbI/SnO interfaces with halogen passivation-induced surface reconstruction but larger for the SnO-terminated cases. Hence, our findings have implications for the design of buried interface optimization in perovskite optoelectronic devices.
通过结合密度泛函理论和分子动力学，我们全面研究了在ETL/钙钛矿界面处通过钝化不同卤素基团（I、F或Cl）进行表面重构后器件的性能增强机制。我们证明，ETL层的卤素基团可以通过平衡界面相互作用、离子迁移和碘化铅骨架来稳定钙钛矿表面的几何结构。尽管卤素钝化分别降低和增加了O端和SnO端的MAPbI₃/SnO₂界面处的界面电荷转移，但根据卤素钝化产生的导带偏移变化，卤素钝化优化了表面重构，并在理论上可以缓解界面载流子复合。此外，MAPbI₃/SnO₂界面的界面载流子复合也与界面间隙态有关，对于具有卤素钝化诱导表面重构的O端MAPbI₃/SnO₂界面，界面间隙态较小，而对于SnO端的情况则较大。因此，我们的研究结果对钙钛矿光电器件中掩埋界面优化的设计具有启示意义。
