Suppressing Cation Micration in Triple-Cation Lead Halide Perovskites



on migration represents an intrinsic instability of metal halide perovskite solar cells. Here we show that triple-cation FAxMAyCs1-x-yPbI3 [FA+ = (NH2)2CH+, MA+ = CH3NH3+] active layers with mixed orthorhombic, post-perovskite (δortho-CsPbI3), and cubic perovskite (α) phases (i.e., α/δ-phase FAxMAyCs1-x-yPbI3) exhibit improved cation stability against applied bias relative to pure α-phase perovskites (i.e., FA0.85Cs0.15PbI3 and FA0.76MA0.15Cs0.09PbI3). Infrared photothermal heterodyne imaging and time-of-flight secondary ion mass spectrometry are used to visualize exclusive α-phase perovskite lateral device A+ cation accumulation (depletion) at perovskite negative (positive) electrode interfaces. The resulting compositional heterogeneities lead to degradation. Operational stability testing of solar cells reveals similar degradation behavior; α/δ-phase FAxMAyCs1-x-yPbI3 lateral devices/solar cells, by contrast, show improved stabilities. Enhanced α/δ-FAxMAyCs1-x-yPbI3 stability is rationalized by δortho-phase inclusions, acting as barriers through which A+ cations do not easily migrate. This study thus provides new insights into cation migration in FAxMAyCs1-x-yPbI3 perovskites and suggests a materials design strategy toward suppressing cation instabilities in hybrid perovskites.


Attribute NameValues
  • Ilia Pavlovetc

  • Michael Brennan

  • Seriu Draguta

  • Anthony Ruth

  • Taylor Moot

  • Jeffrey A. Christians

  • Kyle Aleshire

  • Steve Harvey

  • Stefano Toso

  • Sanjini Nanyakkara

  • Jonah Messinger

  • Joseph Luther

  • Marsaru Kuno

Journal or Work Title
  • ACS Energy Letters

  • 5

  • 9

First Page
  • 2802

Last Page
  • 2810

  • 23808195

Publication Date
  • 2020-08

  • Magellan SEM

  • American Chemical Society

Date Created
  • 2020-11-24

  • English

Departments and Units
Record Visibility Public
Content License
  • All rights reserved

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