Water in Hybrid Perovskites: Bulk MAPbI3 Degradation via Super-Hydrous State

Abstract

Here, first-principles density functional theory calculations are presented which reveal how water incorporation in hybrid halide perovskite[CH3NH3]PbI3 (MAPbI3) catalyzes the phase transition to the ([CH3NH3]PbI3.H2O edge-sharing) monohydrate (colorless) phase, eliminatingits favorable photovoltaic properties. First, fundamental chemical and electrostatic interactions between water and each componentof MAPbI3 are analyzed, demonstrating their dependence on water concentration. Second, the energetics of incorporated water is explored,leading to the discovery of spontaneous phase segregation into dry regions and regions with more than one water per formula unittermedthe super-hydrous state. Third, the properties of the super-hydrous state are analyzed, including the acceleration of octahedron breaking andrearrangement by the high water density. This reveals the phase transformation to be a bulk process, initiated at the super-hydrous regions.This paper concludes with a discussion of how this super-hydrous model explains disparate recent experimental observations concerning thewater-induced transition from (black) perovskite to edge-sharing PbI2 (yellow) phase.

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Document Details

Document Type
Technical Report
Publication Date
Apr 11, 2019
Accession Number
AD1105203

Entities

People

  • Andrew M Rappe
  • Arvin Kakekhani
  • Radhika N. Katti

Organizations

  • University of Pennsylvania

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Band Gaps
  • Boundaries
  • Cells
  • Charge Carriers
  • Chemistry
  • Density Functional Theory
  • Electric Fields
  • Energy Bands
  • Geometry
  • Grain Boundaries
  • Materials
  • Molecular Dynamics
  • Phase Transformations
  • Production Engineering
  • Solar Cells
  • Transitions
  • Two Dimensional

Readers

  • Materials Science and Engineering.
  • Quantum Chemistry
  • Solar Photovoltaics and Thermoelectric Devices.