Quantum dot frontplane for large area X-ray FPDs
Quantum dots(QDs) are tiny solution-processable semiconductor nanoparticles. This class of materials emerged a few decades ago, but only recently QDs appeared in commercial products on the mass market.
QDs have the full potential to revolutionize the area of X-ray imaging due to the set of their unique properties. The proposition of QDI systems is a mammography detector based on quantum dots, which provides high contrast and resolution mammograms for doctors, dose reduction for patients with lower costs for hospitals.
Furthermore, our patented QD technology allows scalable fabrication of semiconductive QD films with the thicknesses ranging from nanometers to hundreds of microns. Depending on the type of QDs, film thickness and device architecture, a wide variety of optoelectronic devices can be fabricated. We have extensive experience in making and stabilizing the dispersions of QDs for direct deposition of semiconductive films, fabrication of QD films by various solution-processable techniques, making and characterizing optoelectronic devices, patterning and encapsulating QD films.
High X-ray absorption
Lead based quantum dots have one of the highest X-ray attenuation coefficients due to 85% mass fraction of lead in the conversion layer. 100 um film thickness is sufficient to absorb >95% photons used for mammography application.
Low dose X-ray imaging
Due to low impact ionization energy, absorbed X-ray photons deposit larger amount of charge in the conversion layer, compared to conventional technologies. The charges are efficiently extracted to the backplane by applying as low as 0.5 V/um electric field. Together with low leakage current, this provides high signal-to-noise ratio even at low dose rates.
High resolution
Quantum dot based frontplane is truly amorphous, consisting of a few nanometer sized crystalline particles. This releases the limits of policrystalline materials where the resolution is constrained by tens of micrometer crystalline domains causing charge sharing between pixels. The resolution of Quantum dot sensors is virtually limited by the pixel size of the backplane.
Solution process
Quantum dot frontpane is deposited from solution and can be manufactured using spray-coating, slot-die coating or other conventional method depending on customer needs and specifications.