Organic Dipole Layers for Ultralow Work Function Electrodes
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- 作者：William E. Ford ; Deqing Gao ; Nikolaus Knorr ; Rene Wirtz ; Frank Scholz ; Zoi Karipidou ; Kodo Ogasawara ; Silvia Rosselli ; Vadim Rodin ; Gabriele Nelles ; Florian von Wrochem
- 刊名：ACS Nano
- 出版年：2014
- 出版时间：September 23, 2014
- 年：2014
- 卷：8
- 期：9
- 页码：9173-9180
- 全文大小：500K
- ISSN：1936-086X
文摘
The alignment of the electrode Fermi level with the valence or conduction bands of organic semiconductors is a key parameter controlling the efficiency of organic light-emitting diodes, solar cells, and printed circuits. Here, we introduce a class of organic molecules that form highly robust dipole layers, capable of shifting the work function of noble metals (Au and Ag) down to 3.1 eV, that is, 鈭? eV lower than previously reported self-assembled monolayers. The physics behind the considerable interface dipole is elucidated by means of photoemission spectroscopy and density functional theory calculations, and a polymer diode exclusively based on the surface modification of a single electrode in a symmetric, two-terminal Au/poly(3-hexylthiophene)/Au junction is presented. The diode exhibits the remarkable rectification ratio of 鈭?路103, showing high reproducibility, durability (>3 years), and excellent electrical stability. With this evidence, noble metal electrodes with work function values comparable to that of standard cathode materials used in optoelectronic applications are demonstrated.