Phase-engineering compact and flexible CsPbBr₃ microcrystal films for robust X-ray detection.

Area of Science:

• Materials Science
• Solid-State Physics
• Photonics

Background:

• All-inorganic cesium lead halide perovskites (CsPbBr3) show promise for direct X-ray detection.
• Challenges exist in fabricating stable, pinhole-free thick films for high-resolution devices.

Purpose of the Study:

• To develop a facile strategy for creating stable, compact, thick perovskite films under ambient conditions.
• To investigate the impact of introducing a 2D CsPb2Br5 phase into CsPbBr3 on photophysical properties and charge transport for X-ray detection.

Main Methods:

• Fabrication of flexible, compact thick films using a non-conductive polymer under ambient conditions.
• Introduction of the 2D CsPb2Br5 phase into CsPbBr3 perovskite crystals.
• Characterization of photophysical properties and charge transport.
• Rietveld refinement to analyze structural changes.

Main Results:

• The dual-phase perovskite films exhibited improved stability and higher voltage operation under X-ray exposure.
• Introduction of the 2D phase induced local distortions and Pb-vacancies in the CsPbBr3 lattice.
• These structural changes increased the ion migration energy barrier, leading to very low dark current and enhanced stability.
• Potential for improved local charge extraction and X-ray image resolution.

Conclusions:

• A novel strategy using a non-conductive polymer enables the fabrication of stable, flexible, thick perovskite films.
• Incorporating a secondary phase (CsPb2Br5) into CsPbBr3 enhances device stability and performance for X-ray detection.
• The findings suggest that phase engineering in perovskites is a viable approach for efficient photon-to-charge conversion in medical imaging applications.