la100123q_si_001.pdf (181.2 kB)
0/0

Monitoring N719 Dye Configurations on (1 × n)-Reconstructed Anatase (100) by Means of STM: Reversible Configurational Changes upon Illumination

Download (181.2 kB)
journal contribution
posted on 17.08.2010 by Marcelo Zuleta, Shun Yu, Sareh Ahmadi, Gerrit Boschloo, Mats Göthelid, Anders Hagfeldt
We report experimental results concerning the STM imaging of cis-bis (isothiocyanate)-bis-(2,2′-bipyridyl-4,4′dicarboxylate)ruthenium(II)bis(tetrabutylammonium) dye (known as N719) adsorbed on a single crystal of anatase TiO2(100). The cleaning pretreatment, by sputtering and annealing, of TiO2(100) yields a reproducible (1 × n) surface reconstruction. Previous to dye deposition, TiO2 was covered with one monolayer of 4-tert-butylpyridine (4-TBP) in ultrahigh vacuum (UHV) in order to protect the surface against air contamination. N719 was subsequently deposited by dipping the crystal into the dye solution. 4-TBP was removed partially in the solution and totally by heating the sample to around 285−300 °C in UHV. The images of the deposited 4-TBP on TiO2(100) revealed a complete surface coverage showing three modes of adsorption on TiO2. The relatively uncomplicated desorption of 4-TBP enables the accommodation and chemisorption of most N719 molecules directly onto the TiO2 surface. The STM imaging of N719 was affected, in a reversible way, by illumination, because the quality of the image changed after a few hours in the dark or under illumination conditions. The results presented herein are discussed in terms of changes in molecular configurations and in open circuit potentials.

History

Exports