Improved conductivity in dye-sensitised solar cells through block-copolymer confined TiO2 crystallisation

Anatase TiO2 is typically a central component in high performance dye-sensitised solar cells (DSCs). This study demonstrates the benefits of high temperature synthesised mesoporous titania for the performance of solid-state DSCs. In contrast to earlier methods, the high temperature stability of mesoporous titania is enabled by the self-assembly of the amphiphilic block copolymer polyisoprene-block-polyethylene oxide (PI-b -PEO) which compartmentalises TiO2 crystallisation, preventing the collapse of porosity at temperatures up to 700 degrees C. The systematic study of the temperature dependence on DSC performance reveals a parameter trade-off: high temperature annealed anatase consisted of larger crystallites and had a higher conductivity, but this came at the expense of a reduced specific surface area. While the reduction in specific surface areas was found to be detrimental for liquid-electrolyte DSC performance, solid-state DSCs benefitted from the increased anatase conductivity and exhibited a performance increase by a factor of three

MICROWAVE SPECTROSCOPIC INVESTIGATION OF HNO3⋯(H2O)2HNO_{3}\cdots(H_{2}O)_{2}

$^{a}$P. R. McCurdy, W. P. Hess, S. S. Xantheas J. Phys. Chem. A 106(33), 7628, (2002).Author Institution: Department of Chemistry, University of Minnesota; Department of Chemistry, Concordia UniversityNitric acid is an important reactive species in the atmosphere and the study of its hydrates is of considerable interest. We report the observation of the 1:2 complex $HNO_{3}\cdots(H_{2}O)_{2}$ via Fourier transform microwave spectroscopy. A-type spectra for a total of 18 isotpomers were recorded, including $^{15}N$, and several $H^{18}_{2}O$ and deuterium containing species. No b-type transitions were found despite calculations predicting a significant dipole moment along the b-principal axis. Spectral splittings observed indicate internal motion of one or both water units within this complex. The $HNO_{3}\cdots(H_{2}O)_{2}$ system adopts a cyclic structure in which the second water unit inserts into the weak, secondary hydrogen bond of $HNO_{3}\cdots(H_{2}O)$, previously studied in our laboratory. The near-linear hydrogen bond between the acidic proton and the closest water unit is $1.632 (16) {\AA}$, a contraction of $0.15 {\AA}$ relative to $HNO_{3}\cdots H_{2}O$. The $O\cdots O$ distance between the hydroxyl unit of the acid and the closest water unit is $2.625(16){\AA}$. Detailed structural analysis, discussion of internal dynamics, and comparison to ab initio $calculations^{a}$ will be presented. Structural characterization of $HNO_{3}\cdots(H_{2}O)_{2}$ will be discussed in the context of proton transfer, as complexes of this nature help answer the fundamental question of how many water molecules are required to ionize a simple mineral acid

Motion for a resolution tabled by Mr. Karl Heinz Mihr pursuant to Rule 47 of the Rules of Procedure on common policy in the telecommunications field. Working Documents 1981-1982, Document 1-246/82, 11 May 1982

The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block- ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure and its influence upon solar cell performance is investigated. Furthermore, the use of a partially sp 2 hybridized structure directing polymer enables the crystallization of porous TiO2 networks at high temperatures without pore collapse, improving its performance in solid-state dye-sensitized solar cells. © 2009 The Royal Society of Chemistry

Improved Conductivity in Dye-sensitised Solar Cells Through Block-copolymer Confined TiO2 Crystallization

Anatase TiO2 is typically a central component in high performance dye-sensitised solar cells (DSCs). This study demonstrates the benefits of high temperature synthesised mesoporous titania for the performance of solid-state DSCs. In contrast to earlier methods, the high temperature stability of mesoporous titania is enabled by the self-assembly of the amphiphilic block copolymer polyisoprene-block-polyethylene oxide (PI-b -PEO) which compartmentalises TiO2 crystallisation, preventing the collapse of porosity at temperatures up to 700 °C. The systematic study of the temperature dependence on DSC performance reveals a parameter trade-off: high temperature annealed anatase consisted of larger crystallites and had a higher conductivity, but this came at the expense of a reduced specific surface area. While the reduction in specific surface areas was found to be detrimental for liquid-electrolyte DSC performance, solid-state DSCs benefitted from the increased anatase conductivity and exhibited a performance increase by a factor of three.This work was funded in part by the EPSRC Nanotechnology Grand Challenges Energy grant (EP/F056702/1), and EP/F065884/1, the Department of Energy (DE-FG02 87ER45298)through the Cornell Fuel Cell Institute (CFCI), the National Science Foundation (DMR-0605856), and the Cornell Universiy KAUST Center for Research and Education. SG acknowledges support by the Studienstiftung des deutschen Volkes and CD thanks the Royal Society for funding. We thank T. Abraham for help with the XRD measurements, P. Laity for help with SAXS measurements, and P.M€uller-Buschbaum for useful discussions

Block copolymer directed synthesis of mesoporous TiO2 for dye-sensitized solar cells

The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block-ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure and its influence upon solar cell performance is investigated. Furthermore, the use of a partially sp(2) hybridized structure directing polymer enables the crystallization of porous TiO2 networks at high temperatures without pore collapse, improving its performance in solid-state dye-sensitized solar cells.

Monolithic Route to Efficient Dye-sensitized Solar Cells Employing Diblock Copolymers for Mesoporous TiO2

We present a material and device based study on the fabrication of mesoporous TiO2 and its integration into dye-sensitized solar cells. Poly(isoprene-block-ethyleneoxide) (PI-b-PEO) copolymers were used as structure directing agents for the sol–gel based synthesis of nanoporous monolithic TiO2 which was subsequently ground down to small particles and processed into a paste. The TiO2 synthesis and the formation of tens of micrometre thick films from the paste is a scalable approach for the manufacture of dye sensitised solar cells (DSCs). In this study, we followed the self-assembly of the material through the various processing stages of DSC manufacture. Since this approach enables high annealing temperatures while maintaining porosity, excellent crystallinity was achieved. Internal TiO2 structures ranging from the nanometre to micrometre scale combine a high internal surface area with the strong scattering of light, which results in high light absorption and an excellent full-sun power conversion efficiency of up to 6.4% in a robust, 3 μm thick dye-sensitized solar cell.M.N., S.H., and U.S. acknowledge the European RTN-6 Network ‘‘Polyfilm’’ and S.H. acknowledges a scholarship of the Bayerische Graduiertenf€orderung. C.D. acknowledges the Royal Society for Funding. This work was funded in part by the EPSRC Nanotechnology Grand Challenges: Energy grant (EP/ F056702/1), the Department of Energy (DE-FG02 87ER45298) through the Cornell Fuel Cell Institute (CFCI), the National Science Foundation (DMR-0605856), and the Cornell University KAUST Center for Research and Education. The sabbatical leaves of U.W. was supported by the Leverhulme Trust and EPSRC. We thank Mathias Kolle for help with Fig. 1 and Richard Friend for valuable discussions and support

Monolithic route to efficient dye-sensitized solar cells employing diblock copolymers for mesoporous TiO2

We present a material and device based study on the fabrication of mesoporous TiO2 and its integration into dye-sensitized solar cells. Poly(isoprene-block-ethyleneoxide) (PI-b-PEO) copolymers were used as structure directing agents for the sol–gel based synthesis of nanoporous monolithic TiO2 which was subsequently ground down to small particles and processed into a paste. The TiO2 synthesis and the formation of tens of micrometre thick films from the paste is a scalable approach for the manufacture of dye sensitised solar cells (DSCs). In this study, we followed the self-assembly of the material through the various processing stages of DSC manufacture. Since this approach enables high annealing temperatures while maintaining porosity, excellent crystallinity was achieved. Internal TiO2 structures ranging from the nanometre to micrometre scale combine a high internal surface area with the strong scattering of light, which results in high light absorption and an excellent full-sun power conversion efficiency of up to 6.4% in a robust, 3 μm thick dye-sensitized solar cell

BLOCK COPOLYMER DIRECTED SYNTHESIS OF MESOPOROUS TIO2 FOR DYE-SENSITIZED SOLAR CELLS

The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block-ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure and its influence upon solar cell performance is investigated. Furthermore, the use of a partially sp(2) hybridized structure directing polymer enables the crystallization of porous TiO2 networks at high temperatures without pore collapse, improving its performance in solid-state dye-sensitized solar cells.open118788sciescopu