Title | Hybrid halide perovskites for advanced X-rays detection systems
Date | September 5, 2022
Abstract | Advanced X-ray medical imaging systems including phase contrast imaging or artificial intelligence algorithms will require a joint improvement of the detector efficiency and spatial resolution. Today’s commercial flat panel X-ray detectors operate in indirect conversion mode with a trade-off in sensitivity and resolution. Reaching high sensitivity, by increasing the scintillator thickness, goes at the expense of the spatial resolution. Direct detection should combine a high sensitivity and a high spatial resolution but has not been yet implemented in general radiography (20-100 keV energy range) to due to lack of satisfactory semi-conducting material.
The demanding specifications required are a combination of low temperature processing of thick (>100µm) layers on large area (≈20 x 20 cm²), cost-effective materials and processes, and high-level optoelectronic properties. Specifically, the ideal semi-conductor for X-ray direct detection has to combine good charge transport properties to insure high X-ray-to-electron conversion rate (the so-called sensitivity), while keeping low the leakage current in the dark (the so-called dark current) which limits the flat panel dynamic range and the minimal detectable dose. Developments in perovskite metal halide semiconductors over the last ten years have raised the prospect of achieving all these characteristics.
In this talk, we will first give some insights about the different perovskites materials and fabrication strategies developed in the literature for the direct detection of X-rays. A more thorough discussion will be carried out on MAPbBr3 single crystals for X-ray detection, and some attempts to reduce the dark current by tuning the halide composition MAPb(BrxCl1-x)3 will be presented. Finally, we will present a solution process in order to grow large area (4 x 4 cm²) thick polycrystalline MAPbBr3 layers directly on a backplane, and a projection toward the final application will be proposed.
