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Defects in Halide Perovskites: Does It Help to Switch from 3D to 2D?
Haibo Xue1,2, Zehua Chen1,2, Shuxia Tao1,2
1Materials Simulation & Modelling, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
ACS Energy Letters
|May 16, 2024
Summary
Two-dimensional (2D) perovskites exhibit lower point defect concentrations than 3D versions, enhancing their stability. However, significant defects in 2D perovskites can introduce deep traps, negatively impacting optoelectronic performance.
Area of Science:
- Materials Science
- Solid-State Physics
- Chemistry
Background:
- Two-dimensional (2D) organic-inorganic hybrid perovskites offer enhanced stability compared to their three-dimensional (3D) counterparts.
- Understanding defect formation is crucial for optimizing perovskite materials.
Purpose of the Study:
- To investigate the equilibrium concentrations of point defects in 2D perovskites (PEA2PbI4, BA2PbI4, PEA2SnI4).
- To compare defect formation energies in 2D versus 3D perovskite structures.
- To explore the impact of alloying on 2D perovskite stability and defect behavior.
Main Methods:
- First-principles calculations were employed.
- Thermodynamic analysis of point defect formation was performed.
- Electronic structure calculations were used to assess defect impact.
Main Results:
- Equilibrium point defect concentrations are significantly lower in 2D perovskites (PEA2PbI4, BA2PbI4, PEA2SnI4) than in 3D perovskites.
- Defect formation is energetically more costly in 2D perovskite networks due to more destructive bonding disruptions.
- Alloying 2D tin iodide perovskites with lead can further enhance their stability.
- Nonequilibrium growth conditions leading to sizable defect concentrations introduce deep traps, hindering optoelectronic performance.
Conclusions:
- 2D perovskites possess inherent stability advantages due to lower defect concentrations.
- The presence of deep traps, arising from substantial point defects, explains the broad sub-bandgap emission observed in 2D perovskites.
- Strategies to minimize defects during growth are essential for realizing the full potential of 2D perovskites in optoelectronic applications.
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