Carbon Nanotube Counter Electrode Research Articles

Improved Efficiency of Dye-Sensitized Solar Cells Using a Vertically Aligned Carbon Nanotube Counter Electrode

Dye-sensitized solar cells (DSSCs) offer many advantages in comparison to their Si-based counterparts, including lower cost of raw materials, faster manufacturing time, and the ability to be integrated with flexible substrates. Although many advances have been made in DSSC fabrication over recent years, their efficiency remains lower than commercially available Si photovoltaic cells. Here we report improved efficiency of TiO2/anthocyanin dye solar cell using vertically aligned arrays of carbon nanotubes (CNTs) as a counter electrode. Dense vertically oriented CNT arrays are grown directly on the counter electrode using microwave plasma chemical vapor deposition and a trilayer (Ti/Al/Fe) catalyst. The resulting arrays are 30 μm in height and have a number density of approximately 5×108/mm2. By directly growing the CNTs on the counter electrode substrate, electrical interface conductance is enhanced. The performance of both as-grown and N-doped (using a nitrogen plasma) CNT arrays is reported. The fabricated DSSCs are tested under AM1.5 light. Increased short-circuit current is observed in comparison to graphite and Pt counter electrodes. We attribute this improvement to the large surface area created by the 3D structure of the arrays in comparison to the planar geometry of the graphite and Pt electrodes, as well as the excellent electrical properties of the CNTs.

Carbon Nanotube Electrode for Iodide/Tri-Iodide Ion Redox Reaction in Dye Sensitized Solar Cell

Carbon nanotubes (CNTs) were used as a counter electrode of a dye sensitized solar cell (DSC) instead of a Pt counter electrode. The CNT electrodes were fabricated by growing CNTs on metal substrates by microwave plasma enhanced chemical vapor deposition (MPCVD). The size and the amount of CNTs that varied with the microwave power of MPCVD improve the electrochemical characteristics of the CNT electrode which is superior to that of Pt counter electrode. The conversion efficiency of DSCs with the CNT counter electrodes was comparable to that with the Pt counter electrode taking into account of the incident light availability. This study suggests that the CNT counter electrode directly grown on metal substrate be promising to accomplish the high energy conversion efficiency of DSC.

Fabrication of double-walled carbon nanotube counter electrodes for dye-sensitized solar sells

Double-walled carbon nanotubes (DWCNTs) have been studied for counter-electrode application in dye-sensitized solar cells (DSCs). Mesoporous TiO2 films are prepared from the commercial TiO2 nanopowders by screen-printing technique on optically transparent-conducting glasses. A metal-free organic dye (indoline dye D102) is used as a sensitizer. DWCNTs are applied to substitute for platinum as counter-electrode materials. Morphological and electrochemical properties of the formed counter electrodes are investigated by scanning electronic microscopy and electrochemical impedance spectroscopy, respectively. The electronic and ionic processes in platinum and DWCNT-based DSCs are analyzed and discussed. The catalytic activity and DSC performance of DWCNTs and Pt are compared. A conversion efficiency of 6.07% has been obtained for DWCNT counter-electrode DSCs. This efficiency is comparable to that of platinum counter-electrode-based devices.

Enhancement of the efficiency of dye-sensitized solar cell by utilizing carbon nanotube counter electrode

We investigated the performance of dye-sensitized solar cells (DSSCs) by applying carbon nanotubes (CNTs) to the counter electrode using two different methods: screen printing and chemical vapor deposition. When the highly purified and aligned CNTs were used as the counter electrode, a conversion efficiency of DSSCs of over 10% was recorded. This CNT-deposited counter electrode shows a higher photoconversion efficiency than CNT-printed and Pt-coated electrodes under the same experimental conditions.

Efficient Dye-Sensitized Solar Cells with Catalytic Multiwall Carbon Nanotube Counter Electrodes

We report the successful application of multiwall carbon nanotubes (CNTs) as electrocatalysts for triiodide reduction in a dye-sensitized solar cell (DSSC). Defect-rich edge planes of bamboolike-structure multiwall CNTs facilitate the electron-transfer kinetics at the counter electrode-electrolyte interface, resulting in low charge-transfer resistance and an improved fill factor. In combination with a dye-sensitized TiO2 photoanode and an organic liquid electrolyte, a multiwall CNT counter-electrode DSSC shows 7.7% energy conversion efficiency under 1 sun illumination (100 mW/cm(2), air mass 1.5 G). The short-term stability test at moderate conditions confirms the robustness of CNT counter-electrode DSSCs.

Spray coated multi-wall carbon nanotube counter electrode for tri-iodide [formula omitted] reduction in dye-sensitized solar cells

Spray coated multi-wall carbon nanotube (CNT) film on fluorine-doped tin oxide glass substrate has been investigated as a counter electrode for tri-iodide reduction in dye-sensitized solar cells. The photovoltaic parameters, in particular, the fill factor shows a strong dependency on the spraying time of multi-wall CNTs. Under one sun illumination (100 mW cm −2, AM 1.5 G), the device shows a maximum energy conversion efficiency of 7.59%. Electrochemical impedance spectroscopy analysis reveals a decrease in the charge transfer resistance of multi-wall CNT counter electrode with increase of spraying time; leads to an improvement in the photovoltaic parameters.

Spray-coated Carbon Nanotube Counter Electrodes for Dye-sensitized Solar Cells

Carbon Nanotube(CNTs) counter electrode is a promising alternative to Platinum counter electrode for dye sensitized solar cells (DSSCs). In this study, CNT counter electrodes having different visible light transmittance were prepared on fluorine-doped tin oxide (FTO) glass surface by spray coating method. Microstructural images show that there are CNT-tangled region coated on FTO glass counter electrodes. Using such CNT counter electrodes and screen printed electrodes, DSSCs were assembled and its I-V characteristics have been studied and compared. Light energy conversion efficiency of DSSCs increased with decreasing in light transmittance of CNT counter electrode. Efficiency of DSSCs having CNT counter electrode is compatible to that of Pt counter electrode.