E-Spray-Deposited CsPbBr₃/Cs₂AgBiBr₆ Type-II Heterojunction Enabling High-Sensitivity Self-Powered X-ray Detection.

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Perovskite Type-II heterojunctions show potential for self-powered X-ray detection due to built-in electric fields.
• Fabricating thick heterojunctions with sharp interfaces via solution processing is challenging.

Purpose of the Study:

• To develop a scalable method for creating thick CsPbBr₃/Cs₂AgBiBr₆ Type-II heterojunctions with sharp interfaces.
• To demonstrate self-powered X-ray detection capabilities of the fabricated heterojunctions.

Main Methods:

• Electrostatic spray (E-spray) deposition with a solvent-compatible layer sequence (DMSO-based CsPbBr₃ followed by DMF-based Cs₂AgBiBr₆).
• Cross-sectional SEM and ToF-SIMS for interface characterization.
• UPS, time-resolved photophysical characterization, and electrical/X-ray response measurements.

Main Results:

• Achieved a sharp interface with minimized intermixing in the thick-film CsPbBr₃/Cs₂AgBiBr₆ heterojunction.
• Demonstrated heterojunction-assisted carrier separation and collection.
• Exhibited self-powered X-ray detection with high sensitivity (226.82 μC Gy_air^-1 cm^-2 at 0 V), low detection limit (0.028 μGy_air s^-1), and operational stability.

Conclusions:

• E-spray deposition offers a scalable strategy for fabricating high-quality perovskite Type-II heterojunctions.
• The developed heterojunctions are promising for high-sensitivity, low-power direct X-ray detectors.
• This work advances perovskite-based applications in X-ray imaging.