THESIS
2021
1 online resource (xxiii, 212 pages) : illustrations (some color)
Abstract
Low dimensional semiconductor materials exhibit unique properties due to quantum and dielectric confinement effects. In particular, lead halide perovskite nanocrystals
have exceptional optoelectronic properties. The first project involves the synthesis of CsPbX
3 perovskite nanorods with a wide range of different morphologies and emission wavelengths covering the entire visible spectrum. An investigation of the nanorods morphology and polarized emission shows that the emission is due to a purely dielectric effect and has no contributions from quantum confinement. Although these perovskite nanorods can exhibit strong polarized emission, we find
that the morphological stability in these materials can lead to loss of polarization. In
solution, these materials will degrade and change morphol...[
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Low dimensional semiconductor materials exhibit unique properties due to quantum and dielectric confinement effects. In particular, lead halide perovskite nanocrystals
have exceptional optoelectronic properties. The first project involves the synthesis of CsPbX
3 perovskite nanorods with a wide range of different morphologies and emission wavelengths covering the entire visible spectrum. An investigation of the nanorods morphology and polarized emission shows that the emission is due to a purely dielectric effect and has no contributions from quantum confinement. Although these perovskite nanorods can exhibit strong polarized emission, we find
that the morphological stability in these materials can lead to loss of polarization. In
solution, these materials will degrade and change morphology regardless of being
stored in an ambient or inert environment due to the highly dynamic nature of the
ligands used. We find that storage of these nanorods in the solid-state in an inert environment is the only approach to prevent degradation without further encapsulation.
To prevent polarization loss of these nanorods, we demonstrate that Si encapsulation
can be used to prevent any changes in the observed polarized emission when stored
in solution for several weeks under ambient conditions. Lead halide perovskites suffer
from their inherent Pb toxicity. Thus lead-free alternatives are needed. Our second
project demonstrates that Cs
3Cu
2Br
5 nanorods can be successfully synthesized using a hot injection approach. However, further improvements in the uniformity of the
nanorods can be obtained by using a new low temperature injection method, as this
provides sufficient separation of the nucleation and growth stages and allows high
aspect ratio nanorods to be synthesized. These high aspect ratio nanorods displayed
a high degree of polarization of 0.89. The final project is focused on using quasi-2D
perovskite for LEDs. Through successful optimization of the printing parameters, we
were able to print PEABr:CsPbBr
3 quasi-2D perovskites. This allowed us to achieve uniform green emissive LED arrays.
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