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Synthesis of Nano-carbon Materials and Its Application in Dye Sensitized Solar Cell Counter Electrode

Author: ZengZuo
Tutor: FangGuoJia
School: Wuhan University
Course: Microelectronics and Solid State Electronics
Keywords: Dye sensitized solar cell counter electrode nano-carbon composite carbon nanoparticles flame synthesis mass transfer model
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Type: PhD thesis
Year: 2013
Downloads: 35
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Abstract

Nano-carbon materials have unique structural, physical and chemical properties, such as large specific surface area, high electrical conductivity, high catalytic activity and low cost. So, it can be a potential alternative for traditional costly platinum material as counter electrode (CE) in dye-sensitized solar cells (DSSCs). In this dissertation, fabrication technologies and elastic stability of nano-carbon CEs have been studied. The main contents are summarized as follow:1) A nano-carbon composite with unique hierarchical porous structure has been effectively fabricated as DSSC CE material by a simple and low-cost way. The fabrication process only employs spin-coating and then combustion by using sodium lauryl sulfate (K12) as a facile pore-forming precursor. The generated composite reveals high catalytic ability coupled with low electrical resistance owing to its unique structure. The power conversion efficiency (PCE) of the resulting DSSC device reaches6.5%, which is close to6.6%of the referenced DSSC by using costly platinum as the CE. A mass transfer model is built and it convincingly demonstrates that the composite architecture is beneficial to carrier transport. The fabrication strategy is simple and effective, and it has a great potential to be applied to DSSC fabrication in a large scale.2) A nano-carbon composite with high electrical conductivity and catalytic ability is fabricated and used as DSSC CE. A Ti metal foil is as CE substrate. A Sn and a Ni film are deposited on the substrated in sequence. Then an aqueous solution composed of nickel sulfate and K12is spin-coatted on the substrate. In ethanol flame, the low-melting Sn layer will melt and reform to a three-dimensional framework structure. The Ni will adhere to the framework and then as growth catalyst to generate carbon composite products composed of carbon nanotubes and carbon nanofibers. The nickel sulfate and K12will fill the framework gap and then generate more nano-carbon. The as-prepared composite reveals high electrical conductivity and enormous catalyst activity. The cell efficiency achieves6.79%, which exceeds6.65%of a reference DSSC by using Pt as CE. A mass transport model is built and the results reflect that the unique architecture is in favor of inner carriers’ transport. Although this fabrication route is complex, it has a potential for preparation of high efficiency DSSC CE. 3) A TiO2-embedded NiCl2gel is prepared and used as growth catalyst to in situ synthesize binded, thick and porous carbon nanoparticles (CNPs) on Ti foil substrate with a simple flame synthesis method for DSSC CE applications. The viscous gel catalyst can hold sufficient NiCl2coated on substrate to make CNP layer thick. The embedded TiO2can effectively separate the abundant NiCl2components to active the Ni catalyst for CNP growth and then make CNP layer become porous. In addition, the TiO2components can bind the porous CNP products to make them conductive. With an optimized TiO2fraction, the CE shows high catalytic ability and electrical conductivity. By applying this CNP CE for DSSC, a PCE of6.6%is achieved, which exceeds6.5%of a reference cell using costly platinum as CE. Furthermore, the CNP structure is demonstrated beneficial to carrier transport by a mass transfer model. This easy and effective preparation method may have a potential application in general nanomaterial preparation.4) An out-of-plane elastic vibration test method is developed to directly study the elastic stability of elastic Ti foil-supported porous carbon nanocomposite (CNC) CE of DSSCs. The stability of CE, estimated by that of PCE of the CE-based DSSC device, is studied from the views of CNC morphology, equivalent resistances, exchange current density and contact model of CE. The results suggest thinner thickness and bigger interbundling degree of CNC layer is beneficial to the total internal impedance value of CE, and then beneficial to the CE stability. With optimal CNC structure, even if the CE is springged1000times with max amplification about20mm, the PCE of CE-based DSSC can remain about80%. The test method is interesting and the results may have a potential use for elastic stability study of general elastic devices.

Synthesis of Nano-carbon Materials and Its Application in Dye Sensitized Solar Cell Counter Electrode

Abstract

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