Ca / CuPc介面的電子結構量測

A Photoemission Study of Electronic Structures at the calcium / copper phthalocyanine Interface

林建宏(Chien-Hung Lin)

指導教授 ： 黃振昌 ； 皮敦文

國立清華大學/工學院/材料科學工程學系/碩士(2007年)

摘要

本次實驗為利用同步幅射光對不同厚度的Ca在CuPc表面上進行光電子能譜的量測，為求表面的敏感性與光能量的因素主要分成兩部份，分別為低能量的價帶能譜與高能量的核層電子能譜，由價帶能譜可以得到介面的電子結構變化，而核層能譜則可解析介面間的化學反應，透過這兩種資訊我們可以了解Ca/CuPc介面的交互作用。
由實驗的觀察可以將其間的交互作用分成四個階段，蒸鍍時間小於15 s：Ca原子提供電子給CuPc使其HOMO與cutoff往高束縛能方向位移。蒸鍍時間小於100 s：HOMO不再位移，Ca與CuPc介面於CuPc能隙之間產生新的波峰且隨Ca厚度增加而增強，並從各核層能譜中觀察到得電子的現象。蒸鍍時間小於500 s：新波峰不再成長，且價帶能譜無明顯變化，Cu原子持續獲得電子。蒸鍍時間大於500 s：Ca鍍厚到金屬態費米能階出現。

關鍵字

有機太陽能電池

並列摘要

In this project, we have utilized synchrotron radiation photoemission to investigate how the organic semiconductor CuPc interacts with Ca at different thicknesses. According to our observations, the interaction at the Ca/CuPc interface can be divided into four stages. In stage I, where the evaporation time is less than 15 s, the Ca atoms transfer some charge to CuPc, making both the HOMO and the cutoff shift to high binding energies. In stage II, where the evaporation time is less then 100 s, a new peak appears inside the CuPc gap, while the HOMO and the cutoff remain unshifted. The new peak increases in intensity with increasing Ca thickness. As to the N 1s and C 1s core-level spectra, they become broadened. Furthermore, a new Cu 3p core appears at low binding energy, shifted away from the pristine 3p core by 1.6 eV. In stage III, where the evaporation time is less than 500 s, the strength of the new valence peak does not increase, and the whole valence band spectra change insignificantly. However, the new Cu 3p core increases in intensity at the expense of the original Cu 3p core. In the final stage, where the evaporation time is greater 500 s, the metallic Ca appears.

參考文獻

3. G. A. Chamberlain, Solar Cells 8, 47 (1983).

6. J. Nelson, Curr. Opin. Solid State Mater. Sci. 6, 87 (2002).

7. J-M. Nunzi, C. R. Physique 3, 523 (2002).

9. C. Winder and N.S. Sariciftci, J. Mater. Chem. 14, 1077 (2004).

10. A. Goetzberger, C. Hebling, and H-W. Schock, Mater. Sci. Eng. R 40, 1 (2003).