X-Site Substituted 2D Cs₂ Pb(SCN)₂ Br₂ Perovskites for X-Ray Detection

Area of Science:

• Materials Science
• Solid-State Physics
• Detector Technology

Background:

• 2D Ruddlesden-Popper (RP) perovskites are known for stability and optoelectrical properties.
• Research on 2D RP perovskites primarily focuses on A-site substitutions, with limited exploration of X-site substitutions, especially for X-ray detection.

Purpose of the Study:

• To investigate X-site substituted 2D RP perovskite Cs2Pb(SCN)2Br2 polycrystalline wafers for X-ray detection.
• To evaluate the optoelectrical properties and performance metrics of these novel perovskite detectors.

Main Methods:

• Preparation of Cs2Pb(SCN)2Br2 polycrystalline wafers.
• Systematic study of their electrical resistivity, ion activation energy, current drift, and charge carrier mobility-lifetime product.
• Characterization of X-ray detection performance, including sensitivity, limit of detection, and spatial resolution.
• Assessment of operational stability under continuous X-ray irradiation and high electric fields.

Main Results:

• The Cs2Pb(SCN)2Br2 wafers exhibited high resistivity (2.0 × 10^10 Ω cm) and ion activation energy (0.75 eV).
• Achieved a high charge carrier mobility-lifetime product (1.29 × 10^-4 cm^2 V^-1) under X-ray.
• Demonstrated excellent X-ray detection sensitivity (216.3 µC Gy_air^-1 cm^-2) and a low limit of detection (42.4 nGy_air s^-1).
• Showcased high spatial resolution (1.08 lp mm^-1) and excellent operational stability up to 2100 V cm^-1 after 45.2 Gy_air irradiation.

Conclusions:

• X-site substituted Cs2Pb(SCN)2Br2 2D RP perovskites are highly suitable for X-ray detection applications.
• Short octahedral spacing and weak ion migration contribute to their superior performance and stability.
• This work opens new avenues for SCN-based 2D perovskites in advanced X-ray detection technologies.