We demonstrated the replacement of the Pt catalyst normally used in the counter electrode of a dye-sensitized solar cell (DSSC) by a nanocomposite of dry spun carbon multi-walled nanotube (MWNT) sheets with graphene flakes (Gr-F). The effectiveness of this counter electrode on the reduction of the triiodide in the iodide/triiodide redox (I − /I − 3 ) redox reaction was studied in parallel with the use of the dry spun carbon MWNT sheets alone and graphene flakes used independent of each other. This nanocomposite deposited onto fluorinated tin-oxide-coated glass showed improved catalytic behavior and power conversion efficiency (7.55%) beyond the use of the MWNTs alone (6.62%) or graphene alone (4.65%) for the triiodide reduction reaction in DSSC. We also compare the use of the carbon MWNT/Gr-F composite counter electrode with a DSSC using the standard Pt counter electrode (8.8%). The details of increased performance of graphene/MWNT composite electrodes as studied are discussed in terms of increased catalytic activity permitted by sharp atomic edges that arise from the structure of graphene flakes or the defect sites in the carbon MWNT and increased electrical conductivity between the carbon MWNT bundles by the graphene flakes.

Our investigation of the chemical and physical properties of the alkali-metal dodecahydro-closo-dodecaborate, Li2B12H12, determined that it is a bi-functional material that can be used as a solid state electrolyte in lithium ion batteries and as a luminescent down conversion dye in scalable transparent displays. A series of electrochemical measurements of morphologically altered samples, via mechanical milling, was conducted. The measurements indicated that mechanical alternations of the Li2B12H12 morphology makes it an excellent lithium ion conductor in the solid state with excepetional ionic conductivity at room temperature (0.31 mS/cm) and is compatible with a metallic lithium electrode up to 6.0V. In addition, all solid state half and full electrochemical cells were assembled and successfully cycled using Li2B12H12 as a solid state electrolyte at temperatures as low as 30°C with good capacity retention. The photophysical properties of Li2B12H12 were also investigated. Li2B12H12 has an emission maximum of ~460 nm in a variety of solvents with Stokes' shifts up to 175 nm observed. Li2B12H12 was incorporated in a polyvinyl alcohol (PVA) thin film to demonstrate its application as a luminescent down-conversion dye in a transparent head-up display when excited by a UV projection source.

Flexible, free-standing transparent conducting electrodes (TCEs) with simultaneously tunable transmittances up to 98% and sheet resistances down to 11 Ω/sq were prepared by a facile spray-coating method of silver nanowires (AgNWs) onto dry-spun multiwall 2 carbon nanotube (MWNT) aerogels. Counterintuitively, the transmittance of the hybrid electrodes can be increased as the mass density of AgNWs within the MWNT aerogels increase, however, the final achievable transmittance depends on the initial transparency of the MWNT aerogels. At the same time, a strong decrease in sheet resistance is obtained when AgNWs form a percolated network along the MWNT aerogel. Additionally, anisotropic reduction in sheet resistance and polarized transmittance of AgNWs/MWNTs aerogel is achieved with this method.The final AgNWs/MWNTs hybrid TCEs transmittance and sheet resistance can be fine-tuned by spray-coating mechanisms or by the choice of initial MWNT aerogel density. Thus, a wide range of AgNWs/MWNTs hybrid TCEs with optimized optoelectronic properties can be achieved depending of the requirements needed. Finally, the free-standing AgNWs/MWNTs hybrid TCEs can be laminated onto a wide range of substrates without the need of a bonding aid.

We describe the use of few-layer graphene nanoribbons, either attached to counter electrodes or dispersed into electrolyte, to induce optical transparency of an iodide/triiodide redox couple in a dye-sensitized solar cell (DSSC). We then evaluate the effect of reversible bleaching of the electrolyte on the DSSC performance. This bleaching effect is related to an energy transfer from photoexcited quantum-dot-like regions to the triiodide (I 3 À ) radical ions in the electrolyte, saturating their absorption in the visible optical range. DSSC power conversion efficiency using few-layer graphene nanoribbons at the counter electrode (5.8%) did not deteriorate when the electrolyte became optically transparent. The increased transparency of the electrolyte resulted in a decreased photocurrent density (from 17.6 to 14.2 mA/cm 2 ), an unchanged open circuit voltage of 750 mV, and a slightly increased fill factor (from 0.45 to 0.55). When the few-layer graphene nanoribbons were introduced into the electrolyte directly by ultrasonication, a semitransparent DSSC was found to have increased its power conversion efficiency in an optically inverted setup from 5.75% to 7.01%, arising from an increase in photocurrent from 9.9 to 12.1 mA/cm 2 . This significant photocurrent increase demonstrates that the effect of electrolyte bleaching can be used for further improving power conversion efficiency for inverted and tandem DSSCs, in which light has to pass through the electrolyte to generate photocurrent on one or more photocells.

Weavable Dye Sensitized Solar Cells (DSSC) made with flexible yarns of conductive multiwalled carbon nanotubes (MWNTs) were produced having a power conversion efficiency above 3%. This was achieved with a specific design and careful consideration of the yarn function in the DSSC. Fermat yarns of MWNTs individually coated with mesoporous TiO2 layer were twisted together and coated with more mesoporous TiO2 to create a 3 dimensional photo electrode to overcome electron diffusion length issues. Archimedian yarns of MWNTs coated with a thin layer of platinum worked as a counter electrode to complete the architecture used in this DSSC.