藉由電子光頻譜研究寡聚芴之未佔態能階

Investigate unoccupied states of homologous oligofluorenes by inverse photoemission spectroscopy

卓孟儀(Meng-Yi Cho)

指導教授 ： 吳志毅

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02330

摘要

因為有機發光二極體層狀結構的關係，在各層有機薄膜之間的交互作用對於此種電激發光元件顯得十分地重要。因此，我們對於有機薄膜的表面及界面都十分的感興趣。而光電子頻譜及電子光頻譜為現今研究固態材料在費米能階上下佔態及未佔態軌域最強而有力且直接的方式。在本論文中，我們將先介紹有機發光二極體及電子光頻譜系統的基本概念並且透過我們所介紹的儀器系統來研究有機材料的電子光頻譜。在此，我們選擇寡聚芴作為研究對象乃因於其在藍光發光領域有引人注目的表現。因此我們將呈現T3及B4的電子光頻譜圖，藉以找出它們的最低未佔態能階軌域。並且與理論計算的頻譜比較，發現相差無幾、特別是在2~4電子伏特的能量範圍內。稍後並結合光電子頻譜及電子光頻譜，找出其帶溝值。然而，在0~4電子伏特的能量範圍內，也許我們無法很明確的指出峰值位置，但是我們希望在未來有朝一日可以改善實驗的缺失，量測出更好的電子光頻譜圖，並且能夠明確指出所有寡聚物之最低未佔態能階，結合光電子頻譜及電子光頻譜可以使我們一窺費米能階附近的表面電子結構。

關鍵字

光電子頻譜 ； 寡聚芴

並列摘要

Because of the multilayer structure of organic light emitting diode（OLED）,the interaction between each organic thin films is important for the electroluminescent devices. Therefore, we are interested in the surface and interface between the organic thin films. The UPS and IPES are the most powerful and direct technologies to study the structure of occupied and unoccupied energy band below and above the Fermi level in the solid state material, respectively. In this thesis, we would introduce the basic concept of OLED and IPES, and study the IPES spectra of organic materials via the system introduced. Here, we chose homologous oligifluorenes, T3 and B4, to investigate because the fluorene-based materials are attractive in the field of the blue emitter. Therefore, we would present the IPES spectra of T3 and B4 to find their LUMO onset. Compared with the calculated IPES spectrum, we find that the calculated spectrum agree approximately with the measured one, especially for the portion with the energies between 2~4 eV. The combined PES and IPES spectra gives the energy gap Eg between the peak onset. However, the IPES peaks are not as clearly defined between 0~4 eV. We hope to measure better IPES spectra and well define the IPES peaks of all the homologous oligofluorenes and then combine PES and IPES spectra to give us more information about surface and interface around the Fermi level in the future.

並列關鍵字

inverse photoemission spectroscopy ； unoccupied ； homologous oligofluorenes

參考文獻

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