M. Drabika, A. M. Zacharyb, Y. Choib, J. Hanusa, J. Touseka, J. Touskovaa, V. Cimrovaa,c, H. Biedermana, L. Hanleyb
aDepartment of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 18000 Prague 8,, Czech Republic
bDepartment of Chemistry, University of Illinois at Chicago, 845 W. Taylor SES 4500 Chicago, IL 60607, USA
cInstitute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic
Titanyl phthalocyanine (TiOPc) thin films were prepared using surface polymerization by ion-assisted deposition (SPIAD) in UHV deposition system. These films were characterized by means of mass spectrometry, X-ray and ultraviolet photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV/Vis absorption spectroscopy, atomic force microscopy, and X-ray diffraction. The measurements revealed an increase in carbon content due to addition of acetylene ions. Level of oxygen in the films indicates production of ions in films. UV/Vis measurement indicates that SPIAD films are more amorphous than evaporated ones. Furthermore, SPIAD causes dimerization between adjacent phthalocyanine molecules at multiple sites. This is consistent with formation of Ti - O - Ti bridge bonding and C=C bonding across various carbon and nitrogen atoms. Also no single dimer dominant leads to amorphous structure. Valence band and elemental content indicate that phthalocyanine electronic and chemical structures are largely preserved during SPIAD.
Further, bilayer thin films of titania (TiO2) and SPIAD TiOPc were prepared. TiO2 film deposited by magnetron sputtering of TiO2 target on the surface served as an electron transporting layer. Study of the samples was focused on the optical and electrical properties of the composite films. The films were characterized by non-contact photovoltage measurements, measurements of I-V characteristics, photoluminiscence and UV-Vis spectroscopy. These measurements suggest there is a possibility to use these bilayer thin films in photovoltaic solar cells, however further experiments to improve conductivity of the films will be required.
Acknowledgements: This work was financed by the grants U.S. NSF CHE-0241425, Kontakt 1P04ME754 and 1M06031 from the Ministry of Education, Youth and Sports of the Czech Republic and IAA4050409 from the Grant Agency of the Academy of Sciences of the Czech Republic.