Atomic structure and electrical/ionic activity of antiphase boundary in CH3NH3PbI3. (1st August 2022)

• Record Type: Journal Article
• Authors: Chen, Shulin; Wu, Changwei; Shang, Qiuyu; Liu, Zhetong; He, Caili; Zhou, Wenke; Zhao, Jinjin; Zhang, Jingmin; Qi, Junlei; Zhang, Qing; Wang, Xiao; Li, Jiangyu; Gao, Peng
• Is Part Of: Acta materialia. Volume 234(2022)
• Publication Date: 2022-08-01
• Subjects: Organic-inorganic hybrid perovskites -- Low dose imaging -- Antiphase boundary -- Electrical activity -- Ion migration; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2022.118010
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Defects in organic-inorganic hybrid perovskites (OIHPs) greatly influence their optoelectronic properties. Identification and better understanding of defects existing in OIHPs is an essential step towards fabricating high-performance perovskite solar cells. However, directly visualizing the defects is still a challenge for OIHPs due to their sensitivity during electron microscopy characterizations. Here, by using low dose scanning transmission electron microscopy techniques, we observe the common existence of antiphase boundary (APB) in CH3 NH3 PbI3 (MAPbI3 ), resolve its atomic structure, and correlate it to the electrical/ionic activities and structural instabilities. Such an APB is caused by the half-unit-cell shift of [PbI6 ] 4− octahedron along the [100]/[010] direction, leading to the transformation from corner-sharing [PbI6 ] 4− octahedron in bulk MAPbI3 into edge-sharing ones at the APB. Based on the identified atomic-scale configuration, we further carry out density functional theory calculations and reveal that the APB in MAPbI3 repels both electrons and holes while serves as a fast ion-migration channel, causing a rapid decomposition into PbI2 that is detrimental to optoelectronic performance. These findings provide valuable insights into the relationships between structures and optoelectronic properties of OIHPs and suggest that controlling the APB is essential for their stability. Graphical abstract: By using low dose scanning transmission electron microscopy techniques, the atomic structure of the antiphase boundary (APB) in CH3 NH3 PbI3 (MAPbI3 ) is revealed. Based on the identified atomic configuration of APB, further density functional theory calculations reveal that the APB in MAPbI3 does not introduce any deep-level defects and repels both electrons and holes while provides a fast-ion-diffusion channel for MA +, Pb 2+ and I −, thus leading to a fast decomposition into PbI2 . Image, graphical abstract