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Photoinduced Charge Transfer from Quantum Dots on the Timescale of Chemistry
Photoinduced Charge Transfer from Quantum Dots on the Timescale of Chemistry
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20250211152002
- ISBN
- 9798383228456
- DDC
- 540
- 서명/저자
- Photoinduced Charge Transfer from Quantum Dots on the Timescale of Chemistry
- 발행사항
- [Sl] : University of Washington, 2024
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2024
- 형태사항
- 116 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-01, Section: B.
- 주기사항
- Advisor: Cossairt, Brandi.
- 학위논문주기
- Thesis (Ph.D.)--University of Washington, 2024.
- 초록/해제
- 요약Measuring and modulating charge-transfer processes at quantum dot interfaces are crucial steps in developing quantum dots as photocatalysts. In Chapter 1, a viewpoint for conceptualizing photoinduced charge transfer as a bimolecular, multi-step process is presented. The conventionally accepted mechanism that charges directly transfer to an acceptor following exciton dissociation is outlined and challenged. Then, existing methodology for evaluating photoinduced charge transfer is introduced. In Chapter 2, cyclic voltammetry under illumination is demonstrated to measure the rate of photoinduced charge transfer from CdS quantum dots by directly probing the changing oxidation states of a library of molecular charge acceptors, including both hole and electron acceptors. Observed rates for photoinduced charge transfer on the order of 0.1 s-1 are measured, which are distinct from the picosecond dynamics measured by conventional transient optical spectroscopy methods. Surprisingly, we found that charge transfer takes ca. 30 min to reach a maximum observed rate and charge transfer lasts for ca. 30 minutes after illumination ends, ~12 orders of magnitude longer than would be expected if charge transfer was directly from exciton dissociation. This timescale challenges the conventionally accepted mechanism of charge transfer.In Chapter 3, we investigated this new pathway for charge storage and transfer. Altogether, our results confirm that excited electrons are stored at ligated surface Cd, these sites are competent charge donors, and this storage is charge balanced by X-type ligand desorption. We found that charge storage occurs in every QD system studied, including CdS, CdSe, and InP capped with carboxylate and phosphonate ligands.
- 일반주제명
- Chemistry
- 일반주제명
- Physical chemistry
- 일반주제명
- Quantum physics
- 일반주제명
- Analytical chemistry
- 키워드
- Quantum dots
- 키워드
- Photocatalysts
- 키워드
- Oxidation states
- 키워드
- Charge storage
- 기타저자
- University of Washington Chemistry
- 기본자료저록
- Dissertations Abstracts International. 86-01B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■006m o d
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■020 ▼a9798383228456
■035 ▼a(MiAaPQ)AAI31330078
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a540
■1001 ▼aHomer, Micaela Kalmek.
■24510▼aPhotoinduced Charge Transfer from Quantum Dots on the Timescale of Chemistry
■260 ▼a[Sl]▼bUniversity of Washington▼c2024
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2024
■300 ▼a116 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-01, Section: B.
■500 ▼aAdvisor: Cossairt, Brandi.
■5021 ▼aThesis (Ph.D.)--University of Washington, 2024.
■520 ▼aMeasuring and modulating charge-transfer processes at quantum dot interfaces are crucial steps in developing quantum dots as photocatalysts. In Chapter 1, a viewpoint for conceptualizing photoinduced charge transfer as a bimolecular, multi-step process is presented. The conventionally accepted mechanism that charges directly transfer to an acceptor following exciton dissociation is outlined and challenged. Then, existing methodology for evaluating photoinduced charge transfer is introduced. In Chapter 2, cyclic voltammetry under illumination is demonstrated to measure the rate of photoinduced charge transfer from CdS quantum dots by directly probing the changing oxidation states of a library of molecular charge acceptors, including both hole and electron acceptors. Observed rates for photoinduced charge transfer on the order of 0.1 s-1 are measured, which are distinct from the picosecond dynamics measured by conventional transient optical spectroscopy methods. Surprisingly, we found that charge transfer takes ca. 30 min to reach a maximum observed rate and charge transfer lasts for ca. 30 minutes after illumination ends, ~12 orders of magnitude longer than would be expected if charge transfer was directly from exciton dissociation. This timescale challenges the conventionally accepted mechanism of charge transfer.In Chapter 3, we investigated this new pathway for charge storage and transfer. Altogether, our results confirm that excited electrons are stored at ligated surface Cd, these sites are competent charge donors, and this storage is charge balanced by X-type ligand desorption. We found that charge storage occurs in every QD system studied, including CdS, CdSe, and InP capped with carboxylate and phosphonate ligands.
■590 ▼aSchool code: 0250.
■650 4▼aChemistry
■650 4▼aPhysical chemistry
■650 4▼aQuantum physics
■650 4▼aAnalytical chemistry
■653 ▼aCharge-transfer process
■653 ▼aQuantum dots
■653 ▼aPhotocatalysts
■653 ▼aOxidation states
■653 ▼aCharge storage
■690 ▼a0485
■690 ▼a0494
■690 ▼a0599
■690 ▼a0486
■71020▼aUniversity of Washington▼bChemistry.
■7730 ▼tDissertations Abstracts International▼g86-01B.
■790 ▼a0250
■791 ▼aPh.D.
■792 ▼a2024
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17162351▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
