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Zhao C.,Dalian University of Technology | Shi Y.,Dalian University of Technology | Zhong Z.,Yingkou Opvtech New Energy Co. | Ma T.,Dalian University of Technology | Ma T.,Yingkou Opvtech New Energy Co.
Cuihua Xuebao/Chinese Journal of Catalysis

Counter electrodes (CEs) for dye-sensitized solar cells (DSCs) are important for collecting electrons and catalyzing the iodide/tri-iodide reaction. Pt CEs are commonly prepared by magnetron sputtering, which is expensive and requires vacuum conditions. Incorporating the low cost surfactant Span-85 improved the adhesion between the Pt particles and conductive substrate, and allowed Pt-based CEs to be screen-printed. The screen-printed CE was compared with those prepared by dip-coating and spin-coating. Photoelectric conversion efficiencies of 7.30%, 6.96% and 7.03% were achieved for DSCs containing screen-printed, dip-coated and spin-coated CEs, respectively. Optical transmittance measurements, scanning electron microscopy, and film adhesion tests results showed that the surfactant improved film adhesion and increased transmittance, and the screen-printed CEs exhibited comparable transmittance to the dip-coated CEs. Screen-printing resulted in Pt particles being more uniformly distributed on the substrate, when compared with dip-coating or spin-coating. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel-polarization curves showed that the catalytic activity of the screen-printed Pt-based CEs were higher than that of the other CEs. Screen-printing is suitable for realizing the low-cost large-scale production of large Pt-based CEs. © 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. Source

Guo W.,Dalian University of Technology | Wang K.,Dalian University of Technology | Shen Y.-H.,Dalian University of Technology | Zhang H.,Yingkou Opvtech New Energy Co. | And 3 more authors.
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica

Mesoporous TiO2 microspheres were synthesized using a simple template method. The effect of the alkyl chain length on the synthesis and properties of the TiO2 microspheres was studied. A high power conversion efficiency (9.5%-10.1%) was attained by the dye-sensitized solar cells (DSCs) fabricated with the hierarchically mesoporous TiO2 microsphere films. The physical properties of the TiO2 microspheres were analyzed by X-ray diffraction (XRD), N2 physisorption (BET), and scanning electron microscopy (SEM). The results indicated the TiO2 microsphere crystal structure to be in the pure anatase phase; the rough surface microstructure of the TiO2 microspheres, formed through accumulation of nanocrystalline (14-18 nm diameter) TiO2 particles, provides a proper large surface area and mesoporous structure. The hierarchically mesoporous TiO2 microspheres can form good paths for mass transport, and also act as light scattering layers for efficient light harvesting. Meanwhile, the rough TiO2 microsphere surface ensures a sufficient amount of dye uptake, and consequently improves the photo-generated electron density. Electrochemical impedance analysis demonstrated the advantage of using microspheres for mass transport in electrolytes. © Editorial office of Acta Physico-Chimica Sinica. Source

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