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Distinct Excitonic Emissions in 2D (C7 H7 N2 )2 PbX4 (X = Cl, Br) under Compression
Hai Zhang1, Peijie Zhang1, Chenlong Xie1
1Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|November 21, 2023
Summary
Pressure induces distinct excitonic emission changes in 2D hybrid metal halides. (C7H7N2)2PbCl4 transitions between free excitonic (FE) and self-trapped excitonic (STE) emissions, while (C7H7N2)2PbBr4 shows only tunable FE emission.
Area of Science:
- Materials Science
- Solid-State Physics
- Photochemistry
Background:
- Two-dimensional hybrid metal halides (2D HMHs) commonly display free excitonic (FE) emission.
- Self-trapped excitonic (STE) emission can be achieved by selecting specific halogens and organic cations.
- Understanding the interplay and transitions between FE and STE emissions in 2D HMHs is an active research area.
Purpose of the Study:
- To investigate the pressure-tuned excitonic emission transitions in 2D HMHs.
- To elucidate the halide-dependent optical responses of these materials under compression.
- To explore the relationship between crystal structure and excitonic emission behavior in 2D HMHs.
Main Methods:
- High-pressure optical spectroscopy was employed to study 2D (C7H7N2)2PbCl4 and 2D (C7H7N2)2PbBr4.
- Comparative analysis of emission spectra under varying pressure conditions.
- Investigation of structural and electronic factors influencing excitonic behavior.
Main Results:
- Intriguing pressure-induced transitions between FE and STE emissions were observed in 2D (C7H7N2)2PbCl4.
- In contrast, 2D (C7H7N2)2PbBr4 exhibited only tunable FE emissions under compression.
- Distinct halide-dependent optical responses are attributed to structural stiffness, cation-octahedra interactions, and octahedral distortion.
Conclusions:
- The study reveals unique pressure-tuned excitonic emission behaviors in halide-substituted 2D HMHs.
- Halide choice significantly impacts the optical response under pressure, influencing FE-STE transition dynamics.
- High-pressure studies are crucial for understanding structure-property relationships in 2D HMHs.
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