Oriented 2D Perovskite Wafers for Anisotropic X-ray Detection through a Fast Tableting Strategy

Area of Science:

• Materials Science
• Optoelectronics
• Crystallography

Background:

• Two-dimensional (2D) perovskite single crystals offer unique anisotropic properties for optoelectronic applications.
• Challenges exist in growing large-area 2D perovskite single crystals, hindering practical applications.
• Existing methods are often time-consuming and complex.

Purpose of the Study:

• To develop a facile and effective method for synthesizing large-area 2D perovskite wafers.
• To investigate a new lead-free 2D perovskite composition for X-ray detection.
• To evaluate the optoelectronic properties and X-ray detection capabilities of the synthesized material.

Main Methods:

• A new lead-free 2D perovskite composition, 4-fluorophenethylammonium bismuth iodide [(F-PEA)₃BiI₆], was synthesized.
• Disordered 2D perovskite powders were processed into oriented bulk wafers using a tableting technique.
• Anisotropic electrical resistivity was measured in lateral and vertical directions.
• X-ray detection performance was evaluated using hard X-rays at 120 kVp.

Main Results:

• A large-area oriented 2D wafer (1.33 cm²) of (F-PEA)₃BiI₆ was successfully fabricated.
• Anisotropic resistivities of 5 × 10¹⁰ Ω cm (lateral) and 2 × 10¹¹ Ω cm (vertical) were observed.
• The material exhibited strong ionic bonding, suppressing ion migration and enabling efficient charge collection.
• The wafer demonstrated sensitive hard X-ray detection with a lowest detectable dose rate of 30 nGy s⁻¹.
• The synthesized wafer showed operational stability comparable to 2D perovskite single crystals.

Conclusions:

• The tableting process is a facile and effective strategy for producing large-area, oriented 2D perovskite wafers.
• The lead-free (F-PEA)₃BiI₆ wafer shows excellent X-ray detection performance and stability.
• This approach offers a promising alternative to traditional single-crystal growth for optoelectronic devices.