Self-Trapped and Free Exciton Dynamics in Vacuum-Deposited Cesium Copper Iodide Thin Films

Chien Yu Chen, Yung I. Lin, Po Ting Lai, Hao Cheng Lin, Guang Hsun Tan, Hao Wu Lin*, Richard D. Schaller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Highly photoluminescent, lead-free perovskites are of interest for displays and solid-state light-emitting devices. In this report, streak camera-based time-resolved emission and transient absorption spanning visible to deep-ultraviolet (UV) wavelengths are utilized to study self-trapped and free exciton dynamics in vacuum-deposited cesium copper halide thin films of CsCu2I3 and Cs3Cu2I5. Self-trapped exciton emission of CsCu2I3 exhibits more noticeable changes with time in the peak position and width than Cs3Cu2I5. UV-to-blue emission is detectable for both compositions, where free exciton emission is distinct for CsCu2I3. Transient absorption shows loss of ground-state bleach signals at early time delays for both, and the bleach signal shifts toward higher energy as time delay increases, likely due to strains induced by the newly created self-trapped excitons. Global analysis performed on the transient absorption results yields time constants in these materials that build an overall dynamic scheme. This work aids in building a complete picture regarding light emission in these promising materials.

Original languageEnglish (US)
Article number2200005
JournalAdvanced Optical Materials
Volume10
Issue number17
DOIs
StatePublished - Sep 5 2022

Keywords

  • carrier dynamics
  • cesium copper iodides
  • self-trapped excitons
  • transient absorption
  • vacuum deposition

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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