Speaker
Description
The use of solution processable materials in direct ionising radiation photodetectors is currently an active research quest that is achieving exciting results. Devices based on Perovskites, Organic Semiconductors, Metal Organic Frameworks and Colloidal Quantum Dots have been demonstrated as efficient, inexpensive and easily processable sensing materials for Gamma, X-rays, Protons or Alpha particles. Perovskite-based detectors typically show the highest sensitivity values among solution processed devices and have been demonstrated for proton detection as well. Organic detectors are generally considered to be tissue-equivalent and have shown photon and proton detection capabilities. Colloidal Quantum Dots have recently started to be employed in direct and indirect ionising radiation detectors. QDs optoelectronic properties depend on their size, surface and core chemistry, and all these properties can be controlled synthesis. In the last few years, direct detectors based on QDs have shown promising sensitivities to x-ray and gamma radiation. QD of High-Z materials like PbS, CdTe and perovskites have much higher photoabsorption coefficients than organics, while photodetectors based on PbS show prolonged (months) stability in ambient air, while often perovskites’ performance is worsened by exposition to humidity and oxygen. In this work, we will initially briefly recap our results on the development of drop-cast PbS QDs X-ray photodetectors on silicon. We will then present our most recent results on PbS on PEN flexible X-ray detectors, highlighting the differences and similarities between the two devices. A preliminary experiment with the PbS on PEN devices also showed a repeatable response to proton beam irradiation, proportional to the proton beam current. These findings suggest that PbS QDs are a promising candidate as efficient, stable and highly optimizable x-ray sensing solution-processable material, with early results suggesting proton detection capabilities as well.
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