Segregation of Native Defects to the Grain Boundaries in Methylammonium Lead Iodide Perovskite

Weitao Shan; Wissam A Saidi

doi:10.1021/acs.jpclett.7b02727

Segregation of Native Defects to the Grain Boundaries in Methylammonium Lead Iodide Perovskite

J Phys Chem Lett. 2017 Dec 7;8(23):5935-5942. doi: 10.1021/acs.jpclett.7b02727. Epub 2017 Nov 27.

Authors

Weitao Shan¹, Wissam A Saidi¹

Affiliation

¹ Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.

PMID: 29160076
DOI: 10.1021/acs.jpclett.7b02727

Abstract

Native point and grain boundary (GB) defects are ubiquitous in methylammonium lead iodide (MAPbI₃) sensitizers employed in solar cells that are polycrystalline in nature. Here we use density functional theory (DFT) in conjunction with a thermodynamic approach to determine the stability and electronic properties of all native point defects and their interplays with Σ5-(210) GB in MAPbI₃. The transition levels of charged defects are investigated with inclusion of electrostatic charge corrections and spin-orbit coupling. We find that the GB region is a sink for most of the native point defects under different synthesis conditions. For the crystalline and bicrystalline MAPbI₃ with Σ5-(210) GB, we find respectively that the p-type antisite defects MA_I and Pb_I, where I substitutes for MA or Pb, introduce deep levels, and both are relatively stable under I-rich conditions. Hence, I-poor conditions are more preferable for synthesis of MAPbI₃ to have defects with electronically benign character.