Metal-Diffusion-Induced Interface Dipole: Correlating Metal Oxide鈥揙rganic Chemical Interaction and Interface Electronic States

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• 作者：Kihyon Hong ; Kisoo Kim ; Sungjun Kim ; Soo Young Kim ; Jong-Lam Lee
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：November 24, 2011
• 年：2011
• 卷：115
• 期：46
• 页码：23107-23112
• 全文大小：911K
• 年卷期：v.115,no.46(November 24, 2011)
• ISSN：1932-7455

文摘

The effects of metal oxide diffusion on the interface dipole (ID) energy at a metal oxide (SnO₂)/organic semiconductor (copper phthalocyanine, CuPc) interface were studied. In situ synchrotron radiation photoelectron spectroscopy and ultraviolet photoemission spectroscopy studies showed that the ID energy for SnO₂-on-CuPc (鈭?.65 eV) was higher by 0.15 eV than that of CuPc-on-SnO₂ (鈭?.50 eV). When SnO₂ deposited on a CuPc layer, hot Sn atoms release enough condensation energy to disrupt the weakly bonded CuPc and diffuse through the surface. The diffused Sn atoms made a chemical reaction with nitrogen atoms in CuPc molecules and made organo-metallic compounds, Sn₂CuPc, resulting in the generation of gap states at the former lowest unoccupied molecular orbital. This observation explains why the ID and hole injection barrier at SnO₂-on-CuPc are larger than those at the CuPc-on-SnO₂ interface. Organic light-emitting diodes with a SnO₂-on-CuPc interface showed a lower luminous efficiency (2.63 cd/A) than that of the device with the CuPc-on-SnO₂ interface (5.26 cd/A), and this result indicates that ID tuning at SnO₂鈥揅uPc interfaces by adjusting the metal diffusion can be readily applicable.