Nanoscale heterogeneity in CsPbBr3 and CsPbBr3:KI perovskite films revealed by cathodoluminescence hyperspectral imaging

Lethy Krishnan Jagadamma, Paul R. Edwards, Robert W. Martin, Arvydas Ruseckas, Ifor D. W. Samuel

Research output: Contribution to journalArticlepeer-review

Abstract

The nanoscale morphology of solar cell materials strongly affects their performance. We report direct evidence for the existence of multiple length scales of heterogeneity in halide perovskites such as CsPbBr3 and CsPbBr3:KI. Contrary to the general notion of two distinct phases, our study suggests the presence of multiple phases in mixed halide perovskites. Highly spatially resolved (≈50 nm) cathodoluminescence maps reveal that the length scale of heterogeneity is composition-dependent: smaller (≈200 nm) for CsPbBr3 and larger (≈500−1000 nm) forCsPbBr3:KI. Moreover, these nano-/micro-scale heterogeneities exist both laterally and vertically in mixed halides and correlate with high densities of carrier traps and fast trap-assisted recombination. The observed heterogeneities also lead to reduced power conversion efficiency of solar cells, higher hysteresis loss, and faster degradation. These insights argue for advanced nanoscale characterization of halide perovskites to guide reduction of heterogeneity and so improve device performance and stability.
Original languageEnglish
Pages (from-to)2707-2715
Number of pages9
JournalACS Applied Energy Materials
Volume4
Issue number3
Early online date8 Mar 2021
DOIs
Publication statusPublished - 22 Mar 2021

Keywords

  • solar cell materials
  • cathodoluminescence
  • power conversion efficiency

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