28277-59-0Relevant articles and documents
Design of organic dyes and cobalt polypyridine redox mediators for high-efficiency dye-sensitized solar cells
Feldt, Sandra M.,Gibson, Elizabeth A.,Gabrielsson, Erik,Sun, Licheng,Boschloo, Gerrit,Hagfeldt, Anders
, p. 16714 - 16724 (2010)
Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO2 films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2′-bipyridyl) cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m-2 AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.
N-substituted 2-pyridinecarbothioamides and polypyridyl mixed-ligand cobalt(III)-containing complexes for photocatalytic hydrogen generation
Bayse, Craig A.,Bullock, Jimmie L.,Celestine, Michael J.,Evaristo, Nicholas K.,Hanan, Garry S.,Holder, Alvin A.,Knarr, James K.,Lawrence, Mark A. W.,Legere, Benjamin W.,McMillen, Colin D.,Picard, Vincent,Schott, Olivier
supporting information, (2020/05/06)
Two mixed-ligand cobalt(III) complexes containing 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen), and N-(3,5-bis(trifluoromethyl)phenyl)pyridine-2-carbothioamide (PCA-(CF3)2) as ligands were synthesized, and characterized by a variety of spectroscopic techniques and elemental analyses. Crystals of the PCA-(CF3)2 molecule are of the monoclinic, C2/c crystal system and space group as determined via X-ray crystallography. The voltammetric properties of six cobalt(III) complexes, [Co(bpy)2Cl2]Cl 1, [Co(phen)2Cl2]Cl 2, [Co(bpy)2(PCA-(CF3)2)](PF6)2·H2O 3, [Co(phen)2(PCA-(CF3)2)](PF6)2·1.25H2O 4, [Co(bpy)3](PF6)3 5, and [Co(phen)3](PF6)3 6, were compared to assess the potential influence of the PCA-(CF3)2 ligand on the effectiveness of cobalt in the catalytic hydrogen evolution reaction (HER) under electrochemical and photochemical conditions. The PCA-(CF3)2 moiety caused an anodic shift in the reduction potential of CoII/I redox couple of complexes 3 and 4, in comparison to the other complexes. Complexes 3 and 4 demonstrated catalytic HER in the presence of p-cyanoanilinium tetrafluoroborate in CH3CN, with overpotentials for the HER of 730 and 630 mV for complexes 3 and 4, respectively. The reduction potentials suggest that the HER was most likely facilitated by a homolytic pathway. Complexes 3 and 4 also demonstrated photocatalytic HER in the presence of [Ru(bpy)3](PF6)2 as a photosensitizer and triethanolamine as a sacrificial reductant in DMF. Complexes 3 and 4 attained rates of 2700 mmol H2.mol?1CAT min?1 and 2600 mmol H2 mol?1CAT min?1, respectively, compared to a standard complex [Co(dmgH)2(py)Cl] which had a rate of 4500 mmol H2 mol?1CAT min?1, under similar conditions. Turnover numbers (TON) of 140 were observed for [Co(dmgH)2(py)Cl] and complex 4, compared to 91 for complex 3, over a 3 h period.
