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DC 欄位 | 值 | 語言 |
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dc.contributor.advisor | 陳俊顯(Chun-hsien Chen) | |
dc.contributor.author | Hsin-jung Lin | en |
dc.contributor.author | 林欣蓉 | zh_TW |
dc.date.accessioned | 2021-06-07T18:06:04Z | - |
dc.date.copyright | 2012-07-30 | |
dc.date.issued | 2012 | |
dc.date.submitted | 2012-07-24 | |
dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16233 | - |
dc.description.abstract | The multibarrier model of metal-molecule-metal (MMM) junction was applied to detailed understanding of charge transport through single-molecule junctions, one of the critical issues for molecular electronics. This model consists of the contact barriers and bridge barrier, in which contact barriers are proportional to the size of the coupling of the headgroup–electrode and the bridge barrier is correlated to EF – EFMOs (the energy differences between Fermi level and frontier molecular orbitals). To systematically study the multibarrier model, we employ the conjugative molecules to lower the EFMOs and change electrode materials to tune EF and coupling strength. Carefully measured herein are the conductances of a series of methylsulfide-terminated biphenyl-oligoyne molecules on Au, Pd, and Pt electrodes by STM BJ (scanning tunneling microscopy break-junction). The results show that the contact resistance (Rc) decreased strongly as simulated bond length of CH3S–electrode decreased, ascribed to the bond strength increased. The characteristic transition voltage (Vtrans), extracted by the I-V curves, is an inflection point on a plot of ln(I/V2) vs. 1/V, consistent with a change in transport mechanism from direct tunneling to field emission and corresponding to total barrier height. The Vtrans values of model compounds decreased with increased conjugation (decreased HOMO–LUMO gap) and increased metal work function (the energy needed to move an electron from the Fermi level). Referring to the multibarrier model, Rc is determined by the contact barriers of molecule-metal interface, and Vtrans is attributed to the contact barrier and the bridge barrier, which was correlated with molecular conjugation. Putting together the aforementioned findings, we provide a comprehensive relation among molecular length, barrier height through MMM, and the measured conductance. In the measurement of I-V characteristics, NDR behavior appears when measuring 1,4-bis(4-(methylthio)phenyl)-buta-1,3-diyne (CH3S-Ph-(C≡C)2-Ph-SCH3) on Au, whereas such phenomena are not found on Pd and Pt electrodes. A plausible explanation for the mechanism of NDR in our research is that the energy of molecule orbital matches/mismatches the spatially discrete energy distribution of the electrode, resulting in diverse energy alignment with oligoynes. | en |
dc.description.provenance | Made available in DSpace on 2021-06-07T18:06:04Z (GMT). No. of bitstreams: 1 ntu-101-R99223104-1.pdf: 3690668 bytes, checksum: a78fd637516f6109bac1c9fd7284bbac (MD5) Previous issue date: 2012 | en |
dc.description.tableofcontents | 中文摘要 i
Abstract iii 總目錄 iv 圖目錄 vii 表目錄 ix 第一章 緒論 1 1.1前言 1 1.2 分子電性測量方法 2 1.2.1 分子膜導電値測量方法 2 1.2.1.1 導電原子力顯微術 3 1.2.1.2 Cross-wire junction 4 1.2.1.3 液態汞滴電極 5 1.2.1.4 Ga2O3/EGaIn液態電極 6 1.2.2 單分子導電性測量方法 7 1.2.2.1 機械式控制破裂接點法 7 1.2.2.2 導電原子力顯微術 9 1.2.2.3 掃描穿隧顯微術 11 1.2.2.4 I(s)及I(t)測量技術 13 1.2.2.5 I(V)測量技術 15 1.3 影響分子導電値之因素 16 1.3.1 分子主體結構的影響 18 1.3.1.1 分子導電性質之衰減常數 19 1.3.1.2 分子主體的電阻 20 1.3.2 分子電極接觸面 23 1.3.2.1 頭基類型及鍵結位向 23 1.3.2.2 電極材料 27 1.3.3 電子傳遞機制及圖譜分析 30 1.4 負微分電阻性質及機制探究 33 1.5 本論文研究目的 39 第二章 實驗部分 40 2.1 藥品、耗材及儀器 40 2.1.1 藥品與耗材 40 2.1.2 實驗儀器 41 2.2 STM BJ 42 2.2.1 溶液系統組裝 42 2.2.2 探針製備 43 2.2.3 單分子導電性測量及數據處理 43 2.3 掃描穿隧能譜:溶液態單分子I-V曲線測量 45 2.4 掃描穿隧能譜:固態單分子I-V曲線測量 45 2.4.1 金(111)表面製備 45 2.4.2 分子修飾探針處理及定點掃描 45 2.4.3 分子I-V曲線測量 46 2.5 紫外光電子能譜 46 2.6 理論計算 46 2.7 目標分子4,4-bis(methylthio)tolane的合成及鑑定 46 第三章 結果與討論 48 3.1 控制實驗:金屬原子串導電值及空白實驗 48 3.2 以金、鈀及鉑電極系統測量共軛雙苯環多炔分子 51 3.2.1 單分子導電值 51 3.2.2 衰減常數及接觸電阻 55 3.2.3 MMM接點靜電電位模型 58 3.2.4 單分子I-V曲線與轉變電壓圖譜 61 3.2.5 負微分電阻性質及機制探究 63 3.3 以掃描穿隧能譜確認負微分電阻行為 65 3.3.1 對電極平整度的確認:金(111)表面重排結構 65 3.3.2 獨立分散分子影像圖 66 3.3.3 掃描穿隧能譜 67 第四章 結論 68 參考文獻 69 附錄 84 | |
dc.language.iso | zh-TW | |
dc.title | 單分子橋接系統電荷傳遞機制探究:雙苯環多炔分子主體和金、鈀及鉑電極接面之能障偶合 | zh_TW |
dc.title | On the Mechanism of Charge Transport in Single-Molecule Junction: Effective Barrier Height of Oligoynes on Au, Pd, and Pt Electrodes | en |
dc.type | Thesis | |
dc.date.schoolyear | 100-2 | |
dc.description.degree | 碩士 | |
dc.contributor.oralexamcommittee | 彭旭明,金必耀 | |
dc.subject.keyword | 單分子電性,負微分電阻, | zh_TW |
dc.subject.keyword | single molecule electronics,negative differential resistance, | en |
dc.relation.page | 87 | |
dc.rights.note | 未授權 | |
dc.date.accepted | 2012-07-25 | |
dc.contributor.author-college | 理學院 | zh_TW |
dc.contributor.author-dept | 化學研究所 | zh_TW |
顯示於系所單位: | 化學系 |
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