Size-Dependent Lattice Symmetry Breaking Determines the Exciton Fine Structure of Perovskite Nanocrystals

Daniel Weinberg*, Yoonjae Park*, David T. Limmer*, Eran Rabani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The order of bright and dark excitonic states in lead-halide perovskite nanocrystals is debated. It has been proposed that the Rashba effect, driven by lattice-induced symmetry breaking, causes a bright excitonic ground state. Direct measurements of excitonic spectra, however, show the signatures of a dark ground state, bringing the role of the Rashba effect into question. We use an atomistic theory to model the exciton fine structure of perovskite nanocrystals, accounting for realistic lattice distortions. We calculate optical gaps and excitonic features that compare favorably with experimental works. The exciton fine structure splittings show a nonmonotonic size dependence due to a structural transition between cubic and orthorhombic phases. Additionally, the excitonic ground state is found to be dark with spin triplet character, exhibiting a small Rashba coupling. We additionally explore the effects of nanocrystal shape on the fine structure, clarifying observations on polydisperse nanocrystals.

Original languageEnglish
Pages (from-to)4997-5003
Number of pages7
JournalNano Letters
Issue number11
StatePublished - 14 Jun 2023


  • Exciton fine structure
  • Excitons
  • Lattice symmetry
  • Nanocrystals
  • Perovskites
  • Rashba effect


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