Energy Level Alignment of Organic Molecules with Chemically Modified Alkanethiolate Self-Assembled Monolayers

Masahiro Shibuta, Munehisa Ogura, Toyoaki Eguchi, Atsushi Nakajima

研究成果: Article査読

3 被引用数 (Scopus)

抄録

We have employed two-photon photoemission spectroscopy to nondestructively resolve the unoccupied energy levels of fullerene C60 molecules deposited on alkanethiolate self-assembled monolayers (SAMs). By fluorine substitution of the hydrogen atoms in the alkyl chain, the work function (WF) increased from 4.3 eV for the alkanethiolate-SAM (H-SAM) to 5.7 eV for the fluorine-substituted SAM (F-SAM), owing to the formation of surface dipole layers. When C60 is deposited on the H-SAM and F-SAM, the energy positions of the unoccupied/occupied levels of C60 are pinned to the vacuum level (Fermi level (EF) + WF). As a result of the energy level alignment, on the F-SAM, the relative energy from EF of the highest occupied molecular orbital of C60 almost equals that of the lowest unoccupied molecular orbital, implying that the C60 film on the F-SAM exhibits both p- and n-type (ambipolar) charge transport properties, while C60 is known as a typical n-type semiconductor. The energetics are preserved even with multilayered C60 films at least up to ∼5 nm in thickness, showing that the dipole layers induced by SAMs are robust against molecular overlayers. Such a spectroscopic study on the energy levels for organic films will be of importance for further development of organic thin film devices.

本文言語English
ページ(範囲)27399-27405
ページ数7
ジャーナルJournal of Physical Chemistry C
121
49
DOI
出版ステータスPublished - 2017 12月 14

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

フィンガープリント

「Energy Level Alignment of Organic Molecules with Chemically Modified Alkanethiolate Self-Assembled Monolayers」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル