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Dynamic Behavior of Bound Interlayer Excitons in Interlayer-Doped Cs3Bi2Br9 Vacancy-Ordered Perovskite
Kyeongdeuk Moon1, Yang Ding2, Halyna Okrepka2
1Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.
ACS Nano
|October 16, 2025
Summary
Silver doping in 2D perovskite Cs3Bi2Br9 creates bound interlayer excitons (BIEs). Temperature-dependent studies reveal distinct emission regimes and ultrafast dynamics, highlighting silver
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid-State Chemistry
Background:
- 2D perovskite Cs3Bi2Br9 (CBB) exhibits unique charge-transfer excited states called bound interlayer excitons (BIEs) upon interlayer doping.
- Silver (Ag+) doping in CBB leads to bright, long-lived photoluminescence (PL) at room temperature, suggesting applications in optoelectronics and photocatalysis.
- Understanding the excited carrier dynamics and radiation processes in Ag-doped CBB (Ag-CBB) is crucial but limited by ensemble measurements.
Purpose of the Study:
- To investigate the temperature-dependent dynamics of Ag-CBB using advanced spectroscopic techniques.
- To elucidate the role of silver dopants in controlling the formation and behavior of BIEs and self-trapped excitons (STEs).
- To understand the fundamental excited-state processes governing light emission and carrier relaxation in this 2D material.
Main Methods:
- Single-particle time-resolved photoluminescence (PL) spectroscopy across a range of temperatures.
- Ultrafast transient absorption imaging using Parallel Rapid Imaging with Spectroscopic Mapping (PRISM).
- Analysis of emission regimes and carrier dynamics at the single-particle level.
Main Results:
- Three distinct emission regimes were identified: BIE-dominant at high temperatures, a mix of BIEs and STEs at intermediate temperatures, and STE-dominant below 100 K.
- PRISM revealed subpicosecond STE formation in pristine CBB and long-lived photoinduced absorption by BIEs in Ag-CBB.
- Spatial uniformity of signals confirmed homogeneous Ag doping, indicating controlled BIE formation.
Conclusions:
- Silver interlayer dopants play a critical role in governing the dynamics of bound interlayer excitons in Cs3Bi2Br9.
- The study provides unprecedented insight into the temperature-dependent interplay between BIEs and STEs at the single-particle level.
- These findings pave the way for designing advanced optoelectronic devices based on tailored exciton dynamics in 2D perovskites.
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