D-π-A dye system containing cyano-benzoic acid as anchoring group for dye-sensitized solar cells.

A D-π-A dye (KM-1) incorporating cyano-benzoic acid as a new acceptor/anchoring group has been synthesized for dye-sensitized solar cells (DSCs) with a high molar extinction coefficient of 66,700 M(-1) cm(-1) at 437 nm. Theoretical calculations show that the hydrogen bond between -CN and surface hydroxyl leads to the most stable configuration on the surface of TiO(2). In addition, the adsorption of the dye on TiO(2) follows a Brunauer-Emmett-Teller (BET) isotherm. Multilayer adsorption of KM-1 on TiO(2) seems to take place particularly at higher dye concentrations. DSC device using KM-1 reached a maximum incident photon-to-current conversion efficiency (IPCE) of 84%, with a solar to electric power conversion efficiency (PCE) of 3.3% at AM1.5 G illumination (100 mW cm(-2)). This new type of anchoring group paves a way to design new dyes that combine good visible light harvesting with strong binding to the metal oxide surface.

Extraordinarily efficient conduction in a redox-active ionic liquid.

Iodine added to iodide-based ionic liquids leads to extraordinarily efficient charge transport, vastly exceeding that expected for such viscous systems. Using terahertz time-domain spectroscopy, in conjunction with dc conductivity, diffusivity and viscosity measurements we unravel the conductivity pathways in 1-methyl-3-propylimidazolium iodide melts. This study presents evidence of the Grotthuss mechanism as a significant contributor to the conductivity, and provides new insights into ion pairing processes as well as the formation of polyiodides. The terahertz and transport results are reunited in a model providing a quantitative description of the conduction by physical diffusion and the Grotthuss bond-exchange process. These novel results are important for the fundamental understanding of conduction in molten salts and for applications where ionic liquids are used as charge-transporting media such as in batteries and dye-sensitized solar cells.

High-efficiency (7.2%) flexible dye-sensitized solar cells with Ti-metal substrate for nanocrystalline-TiO2 photoanode.

High-efficiency flexible dye-sensitized solar cells were fabricated with a Ti-metal foil substrate for photo anode and using a Pt-electrodeposited counter electrode on ITO/polyethylene naphthalate (ITO/PEN); these devices were characterized by incident photon-to-current efficiency (IPCE), optical transmittance and electrical impedance spectroscopy.