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Transforming exciton dynamics in perovskite nanocrystal through Mn doping
Soumen Mukherjee1, Swarnali Ghosh1, Dibyendu Biswas1
1Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
Nanoscale
|March 28, 2023
Summary
Manganese doping significantly alters exciton dynamics in zinc-alloyed cesium lead halide perovskite nanocrystals (PNCs). This study reveals changes in decay rates and enhanced dopant emission, impacting their photoluminescence properties.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Perovskite nanocrystals (PNCs) are promising for optoelectronic applications.
- Manganese (Mn) doping is explored to tune PNC properties, but its effect on exciton dynamics requires detailed understanding.
- Understanding exciton dynamics is crucial for optimizing light emission and charge transport in PNCs.
Purpose of the Study:
- To investigate the impact of Mn doping on exciton dynamics in Zn-alloyed CsPb(Cl/Br)3 perovskite nanocrystals (PNCs).
- To analyze changes in radiative and non-radiative decay rates, dopant emission intensity, and photoluminescence (PL) properties.
- To explore the role of temperature and trap states in modulating the photoluminescence behavior of Mn-doped PNCs.
Main Methods:
- Synthesis of Zn-alloyed CsPb(Cl/Br)3 perovskite nanocrystals (PNCs) with and without Mn doping.
- Photoluminescence (PL) spectroscopy to measure emission maximum, PL quantum yield (PLQY), decay rates, and temperature-dependent behavior.
- Ultrasensitive single-particle spectroscopy to analyze the probability density distributions (PDDs) of ON and OFF events.
Main Results:
- Mn doping decreased the radiative decay rate by ~6.5 times and increased the non-radiative decay rate by ~2.5 times, while maintaining PL emission maximum and PLQY.
- Dopant emission intensity showed a ~5.5-fold enhancement upon cooling from 290 K to 190 K, contrasting with literature reports.
- Single-particle spectroscopy revealed differences in PDDs (IPL vs. TIPL) attributed to shallow trap states and deep dopant states, indicating significant transformation of exciton dynamics.
Conclusions:
- Mn doping profoundly alters exciton dynamics in Zn-alloyed CsPb(Cl/Br)3 PNCs.
- The observed changes in decay rates, enhanced dopant emission, and distinct single-particle behavior highlight the significant influence of Mn on PNC photophysics.
- The findings provide critical insights into the mechanisms governing Mn-doped perovskite nanocrystal luminescence, paving the way for tailored material design.
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