Evaluation of Fullerene-Based Films Ability to Suppress Spontaneous Polymerization

Sammanfattning: The aim of the EU-FP7 Marie Curie project is ‘finding fullerene–coated surfaces with maximum photosensitizing activity.’ The effectiveness of fullerene as the singlet oxygen generator decreases in the case of fullerene is condensed to the bulk material form due to polymerization ability. In this thesis, the task is about finding fullerene coated surfaces with reduced ability to polymerize. In order to study the polymerization, Raman spectroscopy which provides non-destructive, fast and very informative method to get structural and electronic information about the fullerene-based structure was used. The films were irradiated with green laser (514 nm) at the laser power 1.8 mW which is close to the brightest sunlight irradiation, and results show that hydrogen plasma treated C60:H films presents less polymerization ability under the daylight irradiation. The fullerene films co-evaporated with CdS, CdTe, HNO3, TPP (tetraphenylporphyrin) or treated with the hydrogen plasma were produced in St. Petersburg, Russia. Their properties were compared with “C60_ pure” sample. The assessment of the texture was made by atomic force microscopy (AFM). We used spectroscopic ellipsometry which is also a non-destructive method for characterization. The refractive index, extinction coefficient, absorption coefficient and thickness of the films were determined. The films except the “C60_ pure” were nearly transparent in the visible-near UV spectral regions.