Browsing by Author "Spassova E."

Now showing 1 - 4 of 4
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    Directed modification of the properties of vacuum deposited polymer layers by energy-stimulated processes
    (2008-05-01) Dimov D.; Spassova E.; Georgiev A.; Karamancheva I.; Assa J.; Danev G.
    Vacuum deposited thin layers were investigated for obtaining nanocomposite films based on a polyimide matrix and copper phthalocyanine particles as ``guests``. The paper presents a study related to energy-stimulated processes using microwave treatment as an alternative to the classical thermal processing. FTIR spectroscopy investigations demonstrated the possibility for a considerable shortening of the entire treatment process. The best results were obtained by combining the thermal and microwave treatments (15 min microwave + 15 min thermal treatment). © 2008 IOP Publishing Ltd.
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    Ion - Beam assisted process in the physical deposition of organic thin layers
    (2010-01-01) Dimov D.; Georgiev A.; Spassova E.; Assa J.; Danev G.
    A novel method was developed for physical deposition of thin polyimide layers by applying an argon plasma assisted process. The influence was investigated of the plasma on the combined molecular flux of the two thermally evaporated precursors - oxydianiline and pyromellitic dianhydride. The effects observed on the properties of the deposited films are explained with the increased energy of the precursor molecules resulting from the ion-molecular collisions. As could be expected, molecules with higher energy possess higher mobility and thus determine the modification of the films structure and their electrical properties. © 2010 IOP Publishing Ltd.
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    Physical deposition of thin polyimide layers by applying an argon plasma assisted process
    (2010-01-01) Dimov D.; Georgiev A.; Spassova E.; Assa J.; Dineff P.; Danev G.
    A novel method for physical deposition of thin polyimide layers by applying an argon plasma assisted process has been developed. The influence of the plasma on the combined molecular flux of the two thermally evaporated precursors - 4,4'- oxydianiline and pyromellitic dianhydride was investigated. The process parameters were changed in the limlts 0,4 - 2 A for the anode current and 80 - 170 V for the anode voltage. Their influence was studied using FTIR spectroscopy and electron microscopy techniques. It was proposed that the plasma flux crossing the molecular flows of the polyimide precursors enhances the imidization process by partly activating the precursor molecules in the gas phase. © 2010 IOP Publishing Ltd.
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    Thin dye layers - Vacuum deposition and structure
    (2012-01-01) Dimov D.; Assa J.; Georgiev A.; Kazakov R.; Karashanova D.; Danev G.; Spassova E.
    Vacuum-deposited layers of zinc phthalocyanine and perylene-3,4,9,10- tetracarboxylic dianhydride were obtained with regard to the development of converters of solar radiation into electricity, namely, organic solar cells. It was shown that there were no differences in the composition of the initial dyes and the deposited ones, which is a proof of their thermal stability and a prerequisite for the reproducibility of the composition of the single and mixed layers under study. The results obtained are interpreted in view of the possible applicability of the layers studied for the fabrication of organic solar cells in which the processes of creation, the lifetime and the diffusion paths of the current carriers depend significantly on the film composition and the defects formed at the time of deposition of the active dye layers. © Published under licence by IOP Publishing Ltd.