Colloidal Quantum Dots for X-Ray Detection and Imaging

To- date, colloidal quantum dots (CQDs) have been used in a wide array of devices ranging from solar cells, light emitting diodes and field-effect transistors. In this talk, I will present our recent efforts to push the envelope of the applicability of these colloidal QDs towards high energy (X-ray) applications. I will highlight some of our recent results that show the potential of oxide and chalcogenide nanocrystals as efficient hole-blocking and photon conversion interlayers in state-of-the-art amorphous-selenium based X-ray detectors and imagers for mammography. Specifically, we reported the lowest dark current density (30 pA/cm²) ever measured for any solid-state avalanche sensor at room temperature using CeO₂ colloidal quantum dot blocking layers. Secondly, we extended the approach to fabricate hybrid amorphous-selenium and CdSe colloidal QD based hybrid devices with enhanced charge extraction capabilities coupled efficiently to state-of-the-art scintillators demonstrating extremely high specific detectivity (~5*10¹² Jones), fast photo-response with megahertz 3-dB electrical bandwidth (~ 25 MHz), ultra-low dark current density (~10 pA/cm²), low noise current (~20 fW/Hz^1/2) and high linear dynamic range (~150 dB).