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Domain walls and defects in ferroelectric inorganic halide perovskites CsGeX3 (X = Cl, Br, I)

Kristoffer Eggestad, Benjamin A. D. Williamson, and Sverre M. Selbach*

  • *Contact author: selbach@ntnu.no
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Phys. Rev. Materials 10, 064403 – Published 1 June, 2026

DOI: https://doi.org/10.1103/bf5v-24b2

Abstract

Among all-inorganic halide perovskites, the only known ferroelectrics are the family of CsGeX3 (X = Cl, Br, I). Here, we study their ferroelectric domain walls (DWs) and common point defects by density functional theory (DFT) calculations and investigate the interplay between DWs and defects. The most stable defects are VX and VCs and the former shows low migration barriers and high mobility. In contrast to oxide ferroelectrics, the affinity between point defects and DWs is negligible, reflecting the subtle structural distortions at CsGeX3 DWs. Concomitantly, the formation energies and migration energy barriers of CsGeX3 DWs are small compared to oxides, and neither VX nor VCs pin migrating DWs. The band-gap invariance across DWs and the lack of affinity towards intrinsic charged-point defects imply that conducting DWs for nanoelectronics may be challenging to realize in CsGeX3. However, shallow p-type defect levels and low-hole effective masses suggest that high p-type conductivity may be achievable in nominally ferroelectric CsGeX3. The low DW migration energy barriers and insignificant DW pinning by point defects make CsGeX3 promising materials as robust soft ferroelectrics for high-frequency switching applications with low energy dissipation.

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Phys. Rev. Materials 10, 064403– Published 1 June, 2026
  • Received 11 November 2025
  • Accepted 8 May 2026
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