Innovation Through Optical Manipulation: From Parahydrogen Macrocoherence to Enhanced 2D Semiconductors
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Authors
Godfrey, James R.
Date
2024-10-15
Type
thesis
Language
eng
Keyword
lasers , optics , parahydrogen , macroherence , dark photon , mid-infrared , optical parametric amplifier , molybdenum disulfide , 2D materials , photoenhancement , ultrafast , single-photon counting lifetime , reconvolution
Alternative Title
Abstract
While parahydrogen and monolayer MoS2 are quite distinct in their properties and applications, both exemplify the transformative potential of well-established materials when subjected to innovative techniques. The 'new tricks' of monolayer MoS2, compared to its bulk form, arise from its emergent direct bandgap in monolayer form and strongly-bound (100s of meV) excitons that persist at room temperature. However, there is much stubbornness in the 'training' due to lattice defects, vacancies, and an unintentional doping, which impairs the internal PL efficiency known as the PLQY (0.01-6\%, as fabricated). We treat our MoS2 with a TFSI superacid treatment known to massively improve the PLQY, though the mechanisms of enhancement are often debated in the literature. We demonstrate PL enhancement by up to 74x, which is photoinduced over hours. We confirm that the observed photoenhancement requires the presence of ambient air through PL enhancement studies in vacuum. Simultaneous real-time monitoring shows photoenhancement of PL correlates with increasing PL lifetimes measured via SPCL, suggesting that undesired non-radiative recombination is suppressed through the photoenhancement to allow recombination through slower radiative processes. A deeper understanding of these mechanisms could lead to more effective strategies for optimizing the optoelectronic performance of monolayer MoS2.
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution 4.0 International