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Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield / ANUPAMA MUDIYANSELAGE

Swansea University Author: ANUPAMA MUDIYANSELAGE

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Abstract

Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials, exhibiting unique electrical and optical properties as it transitions from the bulk to the nanoscale. Typically, mechanical exfoliation and chemical vapor deposition (CVD) growth methods are used to prepare MoS2 nano...

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Published: Swansea University, Wales, UK 2025
Institution: Swansea University
Degree level: Master of Research
Degree name: MSc by Research
Supervisor: Roy, D.
URI: https://cronfa.swan.ac.uk/Record/cronfa68816
first_indexed 2025-02-06T14:22:24Z
last_indexed 2025-02-07T05:56:37Z
id cronfa68816
recordtype RisThesis
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However, mechanical exfoliation suffers from low yield and CVD based MoS2 growth involves high temperatures and complex costly set-ups. Hence, electro exfoliation has emerged as a promising scalable and cost-effective technique to produce few layer MoS2. In recent years, these MoS2 materials have gained significant importance in catalysis, as the efficient electron transfer facilitated by excitons and trions has proven particularly beneficial for reactions such as the hydrogen evolution reaction (HER). Also, according to the past research these few layers of MoS2 has considerable heterogeneity in their optical and electrical properties due to the presence of defects and discontinuities at the edges. Therefore, investigation of these spatial inhomogeneity is important to use these materials in the real-world applications.The present study was divided into two steps. Firstly, a simple electrochemical exfoliation method was employed to synthesise few-layer MoS2, avoiding the drawbacks associated with existing synthesis processes. The produced MoS2 was then characterised using Raman spectroscopy and photoluminescence spectroscopy to ensure the material's quality and structural integrity. Secondly, these produced few layer MoS2 was used to observe the change of the photoluminescence intensity across a single MoS2 flake and the asymmetric characteristics of trion photoluminescence with applied voltage using in-situ electrochemical setup. Hyperspectral imaging was employed, capturing spectral features from each pixel across a broad field of view rather than individual points.The result from the study indicates that the electro exfoliation method can produce MoS2 flakes with two or three layers on average, and the in-situ electrochemical characterisation showed significant spatial variations and a strong dependence on the voltage, highlighting the influence of electrical layer formation on the photoluminescence from excitons and trions. 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spelling 2025-02-06T14:32:58.7336428 v2 68816 2025-02-06 Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield 98abf540bbb100dffdc5a6f0e07a62b9 ANUPAMA MUDIYANSELAGE ANUPAMA MUDIYANSELAGE true false 2025-02-06 Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials, exhibiting unique electrical and optical properties as it transitions from the bulk to the nanoscale. Typically, mechanical exfoliation and chemical vapor deposition (CVD) growth methods are used to prepare MoS2 nanosheets for optoelectronic studies and applications. However, mechanical exfoliation suffers from low yield and CVD based MoS2 growth involves high temperatures and complex costly set-ups. Hence, electro exfoliation has emerged as a promising scalable and cost-effective technique to produce few layer MoS2. In recent years, these MoS2 materials have gained significant importance in catalysis, as the efficient electron transfer facilitated by excitons and trions has proven particularly beneficial for reactions such as the hydrogen evolution reaction (HER). Also, according to the past research these few layers of MoS2 has considerable heterogeneity in their optical and electrical properties due to the presence of defects and discontinuities at the edges. Therefore, investigation of these spatial inhomogeneity is important to use these materials in the real-world applications.The present study was divided into two steps. Firstly, a simple electrochemical exfoliation method was employed to synthesise few-layer MoS2, avoiding the drawbacks associated with existing synthesis processes. The produced MoS2 was then characterised using Raman spectroscopy and photoluminescence spectroscopy to ensure the material's quality and structural integrity. Secondly, these produced few layer MoS2 was used to observe the change of the photoluminescence intensity across a single MoS2 flake and the asymmetric characteristics of trion photoluminescence with applied voltage using in-situ electrochemical setup. Hyperspectral imaging was employed, capturing spectral features from each pixel across a broad field of view rather than individual points.The result from the study indicates that the electro exfoliation method can produce MoS2 flakes with two or three layers on average, and the in-situ electrochemical characterisation showed significant spatial variations and a strong dependence on the voltage, highlighting the influence of electrical layer formation on the photoluminescence from excitons and trions. Therefore, the correlation between the PL intensity variations and applied voltages provides insights into the dynamics of excitons and trions under electrochemical conditions, paving the way for future studies to explore the full potential of 2D transition metal dichalcogenide materials in catalytic applications. E-Thesis Swansea University, Wales, UK Hyperspectral Imaging, MoS2, Photoluminescence, A-B exciton 7 1 2025 2025-01-07 A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. COLLEGE NANME COLLEGE CODE Swansea University Roy, D. Master of Research MSc by Research 2025-02-06T14:32:58.7336428 2025-02-06T14:03:35.2388040 Faculty of Science and Engineering School of Engineering and Applied Sciences - Chemistry ANUPAMA MUDIYANSELAGE 1 68816__33521__64770e6c0367493cba992928746f0ddc.pdf 2024_Mudiyanselage_A.final.68816.pdf 2025-02-06T14:21:07.4862798 Output 3583747 application/pdf E-Thesis – open access true Copyright: The Author, Anupama B. Patabandi Mudiyanselage, 2024 true eng
title Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
spellingShingle Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
ANUPAMA MUDIYANSELAGE
title_short Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
title_full Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
title_fullStr Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
title_full_unstemmed Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
title_sort Hyperspectral Imaging of Electrochemically Controlled Photoluminescence of Few Layer MoS2 in Widefield
author_id_str_mv 98abf540bbb100dffdc5a6f0e07a62b9
author_id_fullname_str_mv 98abf540bbb100dffdc5a6f0e07a62b9_***_ANUPAMA MUDIYANSELAGE
author ANUPAMA MUDIYANSELAGE
author2 ANUPAMA MUDIYANSELAGE
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publishDate 2025
institution Swansea University
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Chemistry{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Chemistry
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description Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials, exhibiting unique electrical and optical properties as it transitions from the bulk to the nanoscale. Typically, mechanical exfoliation and chemical vapor deposition (CVD) growth methods are used to prepare MoS2 nanosheets for optoelectronic studies and applications. However, mechanical exfoliation suffers from low yield and CVD based MoS2 growth involves high temperatures and complex costly set-ups. Hence, electro exfoliation has emerged as a promising scalable and cost-effective technique to produce few layer MoS2. In recent years, these MoS2 materials have gained significant importance in catalysis, as the efficient electron transfer facilitated by excitons and trions has proven particularly beneficial for reactions such as the hydrogen evolution reaction (HER). Also, according to the past research these few layers of MoS2 has considerable heterogeneity in their optical and electrical properties due to the presence of defects and discontinuities at the edges. Therefore, investigation of these spatial inhomogeneity is important to use these materials in the real-world applications.The present study was divided into two steps. Firstly, a simple electrochemical exfoliation method was employed to synthesise few-layer MoS2, avoiding the drawbacks associated with existing synthesis processes. The produced MoS2 was then characterised using Raman spectroscopy and photoluminescence spectroscopy to ensure the material's quality and structural integrity. Secondly, these produced few layer MoS2 was used to observe the change of the photoluminescence intensity across a single MoS2 flake and the asymmetric characteristics of trion photoluminescence with applied voltage using in-situ electrochemical setup. Hyperspectral imaging was employed, capturing spectral features from each pixel across a broad field of view rather than individual points.The result from the study indicates that the electro exfoliation method can produce MoS2 flakes with two or three layers on average, and the in-situ electrochemical characterisation showed significant spatial variations and a strong dependence on the voltage, highlighting the influence of electrical layer formation on the photoluminescence from excitons and trions. Therefore, the correlation between the PL intensity variations and applied voltages provides insights into the dynamics of excitons and trions under electrochemical conditions, paving the way for future studies to explore the full potential of 2D transition metal dichalcogenide materials in catalytic applications.
published_date 2025-01-07T08:23:33Z
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score 11.058331

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