Halide-Dependent Electronic Structure of Organolead Perovskite Materials

Andrei Buin, Riccardo Comin, Jixian Xu, Alexander H. Ip, Edward H. Sargent

Research output: Contribution to journalArticlepeer-review

211 Scopus citations

Abstract

© 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention both at the experimental and theoretical levels. These materials, in particular methylammonium triiodide, are still limited by poor chemical and structural stability under ambient conditions. Today this represents one of the major challenges for polycrystalline perovskite-based photovoltaic technology. In addition to this, the performance of perovskite-based devices is degraded by deep localized states, or traps. To achieve better-performing devices, it is necessary to understand the nature of these states and the mechanisms that lead to their formation. Here we show that the major sources of deep traps in the different halide systems have different origin and character. Halide vacancies are shallow donors in I-based perovskites, whereas they evolve into a major source of traps in Cl-based perovskites. Lead interstitials, which can form lead dimers, are the dominant source of defects in Br-based perovskites, in line with recent experimental data. As a result, the optimal growth conditions are also different for the distinct halide perovskites: growth should be halide-rich for Br and Cl, and halide-poor for I-based perovskites. We discuss stability in relation to the reaction enthalpies of mixtures of bulk precursors with respect to final perovskite product. Methylammonium lead triiodide is characterized by the lowest reaction enthalpy, explaining its low stability. At the opposite end, the highest stability was found for the methylammonium lead trichloride, also consistent with our experimental findings which show no observable structural variations over an extended period of time.
Original languageEnglish (US)
Pages (from-to)4405-4412
Number of pages8
JournalChemistry of Materials
Volume27
Issue number12
DOIs
StatePublished - Jun 12 2015
Externally publishedYes

Fingerprint Dive into the research topics of 'Halide-Dependent Electronic Structure of Organolead Perovskite Materials'. Together they form a unique fingerprint.

Cite this