X-Ray Detection and Strain Sensing Applications of Colloidal Quantum Dots
Abstract
This thesis investigates CQDs as a fast 10 keV-100 keV x-ray scintillator by functionalizing and experimentally characterizing both the PL spectra and PLdecay of eight varieties of CQDs. In addition, x-ray modeling was conducted to roughly compare scintillating capabilities between different CQDs. Groundwork for future pulsed x-ray scintillator decay tests were discussed. All variants were evaluated for their stability and temporal decay characteristics. Functionalization used four fabrication methods: loading the nano-materials into a polymer matrix, dispersion of CQDs as a thin-film on top of quartz,dispersion of CQDs within a 3D printed honeycomb matrix, and drawing them into a PCF. It was found that CQDs dispersed within a 3D printed honeycomb matrix showed CT properties which brought down their temporal PL decay time by at least half. In addition, the blue shifting of the emission wavelength in a CQD/SU-8-5 system due to CT could have useful implications in future photonic circuits. The fastest calculated biexponential model THA over the tested structures was seen in the CQD-loaded polymer matrix. Commercially available spherical CQDs showed a faster decay time than the experimentally commercially made NPLs. CdS showed to have the fastest decay time with a calculated biexponential model THA of 545 ps within a CQD-loaded polymer, but its QE was poor due to being a core-only material. InP/ZnS was the next fastest decaying material with a calculated biexponential model THA of 562 ps within a CQD-loaded polymer with a better QE due to being a core-shell which makes the most promising of the materials studied in this thesis for x-ray scintillating applications. Furthermore, x-ray modeling of alloyed CQD technology showed promise in higher QE for x-ray scintillation than conventional CQDs. In addition to the x-ray application oriented experiments, the stress-strain optical sensing properties of InP/ZnS were explored.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 20, 2020
- Accession Number
- AD1103366
Entities
People
- Michael D. Sherburne
Organizations
- Air Force Institute of Technology