Nature Communications (Oct 2024)

Robust excitonic light emission in 2D tin halide perovskites by weak excited state polaronic effect

  • Hongzhi Zhou,
  • Qingjie Feng,
  • Cheng Sun,
  • Yahui Li,
  • Weijian Tao,
  • Wei Tang,
  • Linjun Li,
  • Enzheng Shi,
  • Guangjun Nan,
  • Haiming Zhu

DOI
https://doi.org/10.1038/s41467-024-52952-9
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 11

Abstract

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Abstract 2D perovskites hold immense promise in optoelectronics due to their strongly bound electron-hole pairs (i.e., excitons). While exciton polaron from interplay between exciton and lattice has been established in 2D lead-based perovskites, the exciton nature and behavior in the emerging 2D tin-based perovskites remains unclear. By combining spin-resolved ultrafast spectroscopy and sophisticated theoretical calculations, we reveal 2D tin-based perovskites as genuine excitonic semiconductors with weak polaronic screening effect and persistent Coulomb interaction, thanks to weak exciton-phonon coupling. We determine an excited state exciton binding energy of ~0.18 eV in n = 2 tin iodide perovskites, nearly twice of that in lead counterpart, despite of same large value of ~0.2 eV from steady state measurement. This finding emphasizes the pivotal role of excited state polaronic effect in these materials. The robust excitons in 2D tin-based perovskites exhibit excitation power-insensitive, high-efficiency and color-purity emission, rendering them superior for light-emitting applications.