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    Aerosol Flow Homogenization in the Spray Polyphenylene Vinylene Thin Film Deposition
    (IOP Publishing, 2014-05-15) Milenkov, Viktor; Vrchotová, Jana; Zhivkov, Ivaylo; Yordanov, Rumen S.; Vala, Martin; Mladenova, Daniela; Weiter, Martin
    Two different spray deposition (SD) techniques were compared on polyvinylene (MDMO-PPV) used as a model material. SD and homogenized (h-SD) techniques were compared. Films of about 1 micron thickness were prepared by SD and h-SD and normal techniques from toluene solution with a concentration of 0.5 g/l. It was found that the ITO|MDMO-PPV|Al structures with h-SD MDMO-PPV films behave as a photovoltaic cell. Optical micrograph images show structure with typical discs. Current - voltage characteristics measured on samples with h-SD films show that an exposure to a white light increases the current two orders of magnitude.
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    Vacuum deposited Diphenyl-Diketo-Pyrrolopyrrol solar cell structures
    (IOP Publishing, 2016-04-07) Georgieva, Galya; Dobrikov, Georgi; Heinrichová, Patricie; Karashanova, Daniela; Dimov, Deyan; Vala, Martin; Weiter, Martin; Zhivkov, Ivaylo
    In the present paper, DPP(TBFu)2:C60 donor-acceptor composite films were prepared by vacuum co-deposition and the photoelectrical properties of ITO|PEDOT:PSS| DPP(TBFu)2:C60|Al solar cell samples were investigated.
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    Study of Optical and Electrical Properties of Organic Thin Films for Photovoltaic Applications
    (Kaunas University of Technology, 2015-09-02) Pospíšil, Jan; Schmiedová, Veronika; Zmeškal, Oldřich; Černý, Jiří
    The paper deals with the study of optical, electrical and dielectric properties of thin film organic materials suitable for the preparation of optoelectronic devices (e.g. photodiodes, phototransistors, photovoltaic cells). As active layers palladium phthalocyanine (PdPc[t-Bu]4), fullerene (acceptor material, PCBM) and their mixture (9:5 mass %) were used. Thin films were prepared by two methods: by spin coating (Chemat technology Spin Coater) and by material inkjet printing (Dimatix Materials Printer DMP-2800). UV-VIS spectroscopy and ellipsometry were used to study the optical properties. The paper also presents results of electrical and dielectric measurements.
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    Morphology versus Vertical Phase Segregation in Solvent Annealed Small Molecule Bulk Heterojunction Organic Solar Cells
    (Hindawi, 2015-10-11) Kovalenko, Alexander; Pospíšil, Jan; Zhivkov, Ivaylo; Vala, Martin; Weiter, Martin
    The deep study of solvent annealed small molecules bulk heterojunction organic solar cells based on DPP(TBFu)2 : PC60BM blend is carried out. To reveal the reason of the solvent annealing advantage over the thermal one, capacitance-voltage measurements were applied. It was found that controlling the vertical phase segregation in the solar cells a high fullerene population in the vicinity of the cathode could be achieved. This results in increase of the shunt resistance of the cell, thus improving the light harvesting efficiency.
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    Effect of the Side Chains and Anode Material on Thermal Stability and Performance of Bulk-Heterojunction Solar Cells Using DPP(TBFu) 2 Derivatives as Donor Materials
    (Hindawi, 2015-12-08) Kovalenko, Alexander; Vrchotová, Jana; Vala, Martin; Luňák, Stanislav; Weiter, Martin
    An optimized fabrication of bulk-heterojunction solar cells (BHJ SCs) based on previously reported diketopyrrolopyrrole donor,ethyl-hexylated DPP(TBFu)2,aswellastwonewDPP(TBFu)2derivatives with ethyl-hexyl acetate and diethyl acetal solubilizingside-chains and PC60BM as an acceptor is demonstrated. Slow gradual annealing of the solar cell causing the effective donor-acceptor reorganization, and as a result higher power conversion efficiency (PCE), is described. By replacing a hole transportinglayer PEDOT:PSS with MoO3we obtained higher PCE values as well as higher thermal stability of the anode contact interface.DPP(TBFu)2derivative containing ethyl-hexyl acetate solubilizing side-chains possessed the best as-cast self-assembly and highcrystallinity. However, the presence of ethyl-hexyl acetate and diethyl acetal electrophilic side-chains stabilizes HOMO energy ofisolated DPP(TBFu)2donors with respect to the ethyl-hexylated one, according to cyclic voltammetry. Effect of the Side Chains and Anode Material on Thermal Stability and Performance of Bulk-Heterojunction Solar Cells Using DPP(TBFu) 2 Derivatives as Donor Materials.