In a major step forward for radiation detection technology, a research team led by Prof. MENG Gang from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has significantly enhanced the performance of CsPbBr₃-based X-ray detectors by dramatically lowering their detection limit and suppressing noise and ion migration through innovative cooling and defect-passivation strategies.

Their work, published in Applied Physics Letters and Advanced Functional Materials, lays the groundwork for the next generation of safer and more precise X-ray imaging technology.

One of the biggest challenges in utilizing CsPbBr₃ for X-ray detectors has been minimizing noise and improving sensitivity. 

To overcome this, the researchers applied a liquid nitrogen cooling technique to CsPbBr₃ single crystals, effectively eliminating deep-level defects that typically introduce noise. This approach boosted the material's resistivity by two orders of magnitude and reduced the detection limit to 0.054 nGy_air·s⁻¹, enabling the detection of extremely weak X-ray signals.

The team also addressed the issue of ion migration in polycrystalline CsPbBr₃ wafers, which are more practical for large-scale applications. In collaboration with Prof. FANG Xiaosheng's group from Fudan University, they developed a grain boundary passivation method that raised the ion migration activation energy to 0.56 eV. This significantly suppressed dark current drift under high electric fields, allowing the polycrystalline detector to reach a detection limit of 9.41 nGy_air·s⁻¹ while maintaining excellent image contrast.

CsPbBr₃ detectors could dramatically reduce the radiation dose required for X-ray imaging, which is particularly important for vulnerable populations, such as children and pregnant women. This advancement not only offers a clearer path toward next-generation X-ray detectors, but also accelerates the evolution of radiation imaging technology toward greater safety and precision.

Comparison of X-ray imaging results for CsPbBr₃ wafer-based X-ray detectors before and after grain boundary modification (Image by CHEN Ran)