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International Journal of Photoenergy
Volume 2011, Article ID 401356, 6 pages
Research Article

Structure-Dependent 4-Tert-Butyl Pyridine-Induced Band Bending at Ti Surfaces

1Materialfysik, ICT, KTH, Electrum 229, 16440 Stockholm, Sweden
2The University of Queensland, ARC Centre of Excellence for Functional Nanomaterials and Centre for Computational Molecular Science, Australia Institute for Bioengineering and Nanotechnology, The University of Queensland, Qld 4072, Australia
3Physical & Analytical Chemistry Department, Uppsala University, Lägerhyddsvägen 1, 752 37 Uppsala, Sweden

Received 31 May 2010; Accepted 17 August 2010

Academic Editor: J. Anthony Byrne

Copyright © 2011 Mats Göthelid et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The role of 4-tert butyl pyridine (4TBP) adsorption on Ti surface band bending has been studied using photoelectron spectroscopy. Surface oxygen vacancies pin the Fermi level near the conduction band edge on rutile (110). 4TBP preferentially adsorbs in those vacancies and shift the Fermi level to lower binding energy in the band gap. This is done by transferring vacancy excess charge into the empty orbital in the pyridine ring. The anatase (100) surface contains much less oxygen vacancies although the surface is much rougher than the rutile (110). 4TBP adsorption does not have any significant effect on the surface band bending. Thus the positive role associated with 4TBP addition to solar cell electrolytes is suggested to protection against adsorption of other electrolyte components such as Li and I.