Modification of Charge Transfer and Energy Level Alignment at Organic/TiO2 Interfaces

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• 作者：Shun Yu ; Sareh Ahmadi ; Pl Palmgren ; Franz Hennies ; Marcelo Zuleta ; Mats Gthelid
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：August 6, 2009
• 年：2009
• 卷：113
• 期：31
• 页码：13765-13771
• 全文大小：393K
• 年卷期：v.113,no.31(August 6, 2009)
• ISSN：1932-7455

文摘

Adsorption of titanyl phthalocyanine (TiOPc) on rutile TiO₂(110) modified by a set of pyridine derivatives (2,2′-bipyridine, 4,4′-bipyridine, and 4-tert-butyl pyridine) has been investigated using synchrotron radiation based X-ray photoelectron spectroscopy (XPS). For the unmodified TiOPc/TiO₂ system, a strong charge transfer is observed from the first layer TiOPc into the substrate, which leads to a molecular layer at the interface with a depleted highest occupied molecular orbital (HOMO). However, precovering the TiO₂ surface with a saturated pyridine monolayer effectively reduce this process and leave the TiOPc in a less perturbed molecular state. Furthermore, the TiOPc HOMO and core levels are observed at different binding energies ranging by 0.3 eV on the three pyridine monolayers, which is ascribed to differences in surface potentials set up by the different pyridine/TiO₂ systems.