Pressure induced structural and electronic band transition in CsPbBr₃

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Cesium lead bromide (CsPbBr3) is a key halide perovskite material.
• It possesses significant optoelectronic properties valuable for various applications.

Purpose of the Study:

• To investigate the effect of pressure on the crystal structure and electronic properties of CsPbBr3.
• To understand the relationship between structural transitions and electronic band structure modifications.

Main Methods:

• High-pressure experiments up to 5 GPa at room temperature.
• X-ray diffraction to analyze crystal structure changes.
• Density Functional Theory (DFT) calculations for electronic band structure analysis.

Main Results:

• Observed a phase transition from orthorhombic (Pnma) to monoclinic (P21/c) at 2.08 GPa.
• Detected an ~8% density increase across the phase transition.
• DFT calculations revealed an emergent indirect bandgap at the transition boundary.
• The electronic band gap increased from 2.07 eV to 2.38 eV, correlating with observed color changes.

Conclusions:

• Pressure significantly modulates the crystal structure and electronic properties of CsPbBr3.
• The Pnma-P21/c phase transition is accompanied by a change in band structure and band gap.
• In-situ crystal structure analysis is crucial for accurate electronic band structure calculations in halide perovskites.