PbS Quantum Dots for Direct Conversion X-ray Imaging Applications

PbS quantum dots (QDs), when deposited as a film, form a photosensitive semiconductor layer applicable in various sensors. For example, this material has recently appeared on the market as an active layer of SWIR (short-wave infrared) cameras. Another less explored application for QDs is direct conversion X-ray detection, which will be presented in the talk.

In direct conversion sensors, X-rays are captured and converted to electrical charges in a single step in a photosensitive semiconductor frontplane, yielding the best resolution images in the market. There is a single material used in large area X-ray detectors (for example, mammography application): amorphous selenium. However, this material is associated with certain flaws, such as low sensitivity at low dose, not being able to detect X-rays harder than approximately 30keV and complex manufacturing procedures. This, respectfully, increases the patient’s radiation dose during the imaging exam, limits the application to soft X-rays (mostly mammography) and is a costly solution for hospitals.

PbS QDs, when applied for direct conversion X-ray detectors, release the limitations of amorphous selenium. Due to high mass fraction of lead in the material, the QD frontplane is sensitive for higher X-ray energies expanding the application of large area direct conversion sensors beyond mammography to other (non)-medical applications. Good charge transport properties allow benefits of high sensitivity even at low radiation doses decreasing the dose for patients. High stability and scalable manufacturing methods driving cost reduction for vendors and, subsequently, for health care providers.