Dye molecular structure device open-circuit voltage correlation in Ru(II) sensitizers with heteroleptic tridentate chelates for dye-sensitized solar cells.

Dicarboxyterpyridine chelates with π-conjugated pendant groups attached at the 5- or 6-position of the terminal pyridyl unit were synthesized. Together with 2,6-bis(5-pyrazolyl)pyridine, these were used successfully to prepare a series of novel heteroleptic, bis-tridentate Ru(II) sensitizers, denoted as TF-11-14. These dyes show excellent performance in dye-sensitized solar cells (DSCs) under AM1.5G simulated sunlight at a light intensity of 100 mW cm(-2) in comparison with a reference device containing [Ru(Htctpy)(NCS)(3)][TBA](3) (N749), where H(3)tctpy and TBA are 4,4',4"-tricarboxy-2,2':6',2"-terpyridine and tetra-n-butylammonium cation, respectively. In particular, the sensitizer TF-12 gave a short-circuit photocurrent of 19.0 mA cm(-2), an open-circuit voltage (V(OC)) of 0.71 V, and a fill factor of 0.68, affording an overall conversion efficiency of 9.21%. The increased conjugation conferred to the TF dyes by the addition of the π-conjugated pendant groups increases both their light-harvesting and photovoltaic energy conversion capability in comparison with N749. Detailed recombination processes in these devices were probed by various spectroscopic and dynamics measurements, and a clear correlation between the device V(OC) and the cell electron lifetime was established. In agreement with several other recent studies, the results demonstrate that high efficiencies can also be achieved with Ru(II) sensitizers that do not contain thiocyanate ancillaries. This bis-tridentate, dual-carboxy anchor configuration thus serves as a prototype for future omnibearing design of highly efficient Ru(II) sensitizers suited for use in DSCs.

[1]  Feifei Gao,et al.  A new heteroleptic ruthenium sensitizer enhances the absorptivity of mesoporous titania film for a high efficiency dye-sensitized solar cell. , 2008, Chemical communications.

[2]  Neil Robertson,et al.  Optimizing dyes for dye-sensitized solar cells. , 2006, Angewandte Chemie.

[3]  N. Russo,et al.  SOLVENT EFFECTS COMPUTED WITH THE GAUSSIAN DENSITY FUNCTIONAL METHOD , 1997 .

[4]  Michael Grätzel,et al.  Solar energy conversion by dye-sensitized photovoltaic cells. , 2005, Inorganic chemistry.

[5]  Ying Fu,et al.  Improvement of dye-sensitized solar cells: what we know and what we need to know , 2010 .

[6]  S. Anandan.  Recent improvements and arising challenges in dye-sensitized solar cells , 2007 .

[7]  A. Klamt,et al.  COSMO : a new approach to dielectric screening in solvents with explicit expressions for the screening energy and its gradient , 1993 .

[8]  E. Palomares,et al.  Dye structure–charge transfer process relationship in efficient ruthenium-dye based dye sensitized solar cells , 2010 .

[9]  M. Fischer,et al.  Metal-free organic dyes for dye-sensitized solar cells: from structure: property relationships to design rules. , 2009, Angewandte Chemie.

[10]  Yun Chi,et al.  Tris(thiocyanate) ruthenium(II) sensitizers with functionalized dicarboxyterpyridine for dye-sensitized solar cells. , 2011, Angewandte Chemie.

[11]  Min Zhang,et al.  An Extremely High Molar Extinction Coefficient Ruthenium Sensitizer in Dye-Sensitized Solar Cells: The Effects of π-Conjugation Extension , 2009 .

[12]  Paolo G. Bomben,et al.  Strategies for Optimizing the Performance of Cyclometalated Ruthenium Sensitizers for Dye-Sensitized Solar Cells , 2011 .

[13]  Yun Chi,et al.  Contemporary progresses on neutral, highly emissive Os(II) and Ru(II) complexes. , 2007, Chemical Society reviews.

[14]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations , 1984 .

[15]  Laurence M. Peter,et al.  The Grätzel Cell: Where Next? , 2011 .

[16]  Andreas Klamt,et al.  Incorporation of solvent effects into density functional calculations of molecular energies and geometries , 1995 .

[17]  Jun-Ho Yum,et al.  Recent developments in solid-state dye-sensitized solar cells. , 2008, ChemSusChem.

[18]  Michael Grätzel,et al.  Design and development of functionalized cyclometalated ruthenium chromophores for light-harvesting applications. , 2011, Inorganic chemistry.

[19]  Juan Bisquert,et al.  Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy , 2005 .

[20]  P. Chou,et al.  Strategic design and synthesis of novel tridentate bipyridine pyrazolate coupled Ru(II) complexes to achieve superior solar conversion efficiency , 2009 .

[21]  Michael Grätzel,et al.  Recent advances in sensitized mesoscopic solar cells. , 2009, Accounts of chemical research.

[22]  G. Boschloo,et al.  A Study of the Interactions between I-/I3- Redox Mediators and Organometallic Sensitizing Dyes in Solar Cells , 2009 .

[23]  Molecular Designs and Syntheses of Organic Dyes for Dye-Sensitized Solar Cells , 2009 .

[24]  E. Palomares,et al.  Ruthenium Polypyridyl Sensitisers in Dye Solar Cells Based on Mesoporous TiO2 , 2011 .

[25]  Seth R. Marder,et al.  Energy levels, charge injection, charge recombination and dye regeneration dynamics for donor–acceptor π-conjugated organic dyes in mesoscopic TiO2 sensitized solar cells , 2011 .

[26]  J. Nelson,et al.  Iodide Electron Transfer Kinetics in Dye-Sensitized Nanocrystalline TiO2 Films , 2002 .

[27]  Alex B. F. Martinson,et al.  Advancing beyond current generation dye-sensitized solar cells , 2008 .

[28]  Yun Chi,et al.  Neutral, panchromatic Ru(II) terpyridine sensitizers bearing pyridine pyrazolate chelates with superior DSSC performance. , 2009, Chemical communications.

[29]  H. Sugihara,et al.  Significant efficiency improvement of the black dye-sensitized solar cell through protonation of TiO2 films. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[30]  Y. Yamashita,et al.  Molecular Design of Organic Dye toward Retardation of Charge Recombination at Semiconductor/Dye/Electrolyte Interface: Introduction of Twisted π-Linker , 2010 .

[31]  P. Chou,et al.  Development of thiocyanate-free, charge-neutral Ru(II) sensitizers for dye-sensitized solar cells. , 2010, Chemical communications.

[32]  Nicholas J Long,et al.  Molecular control of recombination dynamics in dye-sensitized nanocrystalline TiO2 films: free energy vs distance dependence. , 2004, Journal of the American Chemical Society.

[33]  Yun Chi,et al.  Ruthenium(II) sensitizers with heteroleptic tridentate chelates for dye-sensitized solar cells. , 2011, Angewandte Chemie.

[34]  P. C. Hariharan,et al.  Accuracy of AH n equilibrium geometries by single determinant molecular orbital theory , 1974 .

[35]  Minoru Sakurai,et al.  Physical Origin of the Opsin Shift of Bacteriorhodopsin. Comprehensive Analysis Based on Medium Effect Theory of Absorption Spectra , 1998 .

[36]  P. Liska,et al.  Engineering of efficient panchromatic sensitizers for nanocrystalline TiO(2)-based solar cells. , 2001, Journal of the American Chemical Society.

[37]  Anders Hagfeldt,et al.  How the nature of triphenylamine-polyene dyes in dye-sensitized solar cells affects the open-circuit voltage and electron lifetimes. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[38]  Ashraful Islam,et al.  Dye-Sensitized Solar Cells with Conversion Efficiency of 11.1% , 2006 .

[39]  J. Baldwin,et al.  Significant enhancement of the Stille reaction with a new combination of reagents-copper(I) iodide with cesium fluoride. , 2005, Chemistry.

[40]  Helena Ribeiro,et al.  Dye-sensitized solar cells: A safe bet for the future. , 2008 .

[41]  J. Durrant,et al.  A new ruthenium polypyridyl dye, TG6, whose performance in dye-sensitized solar cells is surprisingly close to that of N719, the ‘dye to beat’ for 17 years , 2008 .

[42]  Paolo G. Bomben,et al.  A trisheteroleptic cyclometalated Ru(II) sensitizer that enables high power output in a dye-sensitized solar cell. , 2011, Angewandte Chemie.

[43]  Masanori Miyashita,et al.  Substituted carbazole dyes for efficient molecular photovoltaics: long electron lifetime and high open circuit voltage performance , 2009 .

[44]  A. Spek,et al.  Cyclometalated ruthenium complexes for sensitizing nanocrystalline TiO2 solar cells. , 2007, Chemical communications.

[45]  Klaas Bakker,et al.  Measuring charge transport from transient photovoltage rise times. A new tool to investigate electron transport in nanoparticle films. , 2006, The journal of physical chemistry. B.

[46]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[47]  G. Koten,et al.  Cyclometalated Organoruthenium Complexes for Application in Dye-Sensitized Solar Cells , 2010 .

[48]  Ivano Tavernelli,et al.  New paradigm in molecular engineering of sensitizers for solar cell applications. , 2009, Journal of the American Chemical Society.

[49]  Emilio Palomares,et al.  Sensitizer molecular structure-device efficiency relationship in dye sensitized solar cells. , 2011, Chemical Society reviews.

[50]  P. Liska,et al.  Fabrication of thin film dye sensitized solar cells with solar to electric power conversion efficiency over 10 , 2008 .

[51]  Moon-Sung Kang,et al.  A new class of cyclometalated ruthenium sensitizers of the type ĈNN for efficient dye-sensitized solar cells. , 2011, Inorganic chemistry.

[52]  Seigo Ito,et al.  Photovoltaic characterization of dye‐sensitized solar cells: effect of device masking on conversion efficiency , 2006 .

[53]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations. Potentials for main group elements Na to Bi , 1985 .

[54]  Simona Fantacci,et al.  Synthesis, characterization, and DFT-TDDFT computational study of a ruthenium complex containing a functionalized tetradentate ligand. , 2006, Inorganic chemistry.

[55]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals , 1985 .

[56]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .