Computed Tomography (CT) is a leading imaging modality in healthcare. It is fast, cheap and offers a very high resolution. But it also comes with an important disadvantage: it exposes patients to ionizing radiation. It is a permanent strategy in x-ray imaging is to lower the necessary irradiation dose in order to reduce the side effects related to ionizing radiation. Our project is based on the CH3NH3PbI3 photovoltaic perovskite material, which creates with high efficiency photoelectrons (used for digital image creation) upon illumination (with a broad range of photon energies, including that of x-rays). Our invention is to use this material in nanowires form (invented by our laboratory) deposited on graphene surface, which amplifies the effect of photons, reaching sensitivity up to a single photon. This gives several opportunities: reducing radiation levels, allowing more CT scans and/or opening up new applications (e.g. pediatric); new CT approaches for functional imaging, e.g. multi-energy CT, movie-CT, etc. Our project has made a great progress towards creating a “safer” x-ray imaging device. The developed detector shows a sensitivity of (4.8 x105 µC Gyair-1 cm-2) at low dose-rates is one order of magnitude higher than the best perovskite-based X-ray detector and more than four orders of magnitude higher than the sensitivity of the best selenium detectors. It has an excellent stability in time (under bias voltage of 100 mV) and high photocurrent up to 3 µA. This is the highest sensitivity achieved so far with halide perovskites, and shows the future potential of this technology in a new generation of x-ray detectors.
