A new high molar extinction coefficient organic-ruthenium(II) polypyridyl complex sensitizer (
The increasing demand for power supply as well as environmental concern for the consumption of fossil fuel have triggered a greater focus all over the world on renewable energy sources over the past decades [
In order to further improve the efficiency of DSSC devices based ruthenium(II) sensitizers one has to improve its near-IR absorption because of its absorption maxima restricted at around 550 nm and more over the molar absorption coefficient of ruthenium(II) complexes are low causing use of thicker TiO2 layers which further has disadvantage of achieving higher open circuit potential. Hence, research to find optimum ruthenium-based sensitizers has been focused primarily on enhancing the molar absorption coefficient as well as broadening of the metal-to-ligand charge transfer band. For this reason, Gratzel and coworkers have increased the molar extension coefficient of ruthenium(II) complexes by introducing extended
Molecular structure of
4,4′-dicarboxylic acid-2,2′-bipyridine (
The ligand
A mixture of ligand
4,4′-dicarboxylic acid-2,2′- bipyridine (75 mg, 0.308 m mol) was dissolved in dry DMF at 80°C. To this DMF, solution of
UV-Vis spectra were measured in a 1 cm pathlength quartz cell using a Shimadzu model 1700 spectrophotometer. Steady state fluorescence spectra were recorded on a Spex model Fluoromax-3 spectrofluorometer using a 1 cm quartz cell. Solutions having optical density at the wavelength of excitation (
A screen-printed single- or double-layer film of interconnected TiO2 particles was used as mesoporous negative electrode. A 10
The photovoltaic performance of the dye-sensitized nanocrystalline TiO2 cells was determined using the simulator SOLARONIX SA SR-IV unit Type 312. The spectral response was determined by measuring the wavelength dependence of the incident photon-to-current conversion efficiency (IPCE) using light from a 100-W xenon lamp that was focused onto the cell through a double monochromator. The current-voltage characteristics were determined by applying an external potential bias to the cell and measuring the photocurrent using a Keithley model 2420 digital source meter, and a 1000-W xenon lamp was used as the irradiation source. The spectral output of the lamp is set matched the AM 1.5 solar spectrum in the region of 350–750 nm (mismatch 1.9%).
The details of the synthetic strategy adopted for the synthesis of
Figure
UV-visible emission and electrochemical data.
Sensitizer | |||||||
Ox | Red | ||||||
498 (16.046) | 690 | 0.72 | −1.05 | −1.47 | 1.65 | −0.93 | |
540 (10,040) | 720 | 0.65 | −0.98 | −1.64 | 1.62 | −1.02 |
Electronic absorption spectra of (
Absorption (—) and emission spectra in ethanol and absorption (- - -) spectra adsorbed onto a 6
With a view to evaluate HOMO-LUMO levels of
To know the electronic distribution of
The performance of newly synthesized
Molecular orbital spatial orientation of
Photocurrent action spectra of (brown line)
Figure
Photovoltaic performance of
Sensitizer | |||||
---|---|---|---|---|---|
RD-Cou | Z580 | 8.80 | 650 | 0.68 | 4.24 |
Z-907 | Z580 | 11.97 | 650 | 0.68 | 5.20 |
Current-voltage characteristics: (brown line)
We have examined the thermal stability of new ruthenium(II) polypyridyl sensitizer and compared their thermal stability with that of the standard sensitizer
TG/DTG curves of
In conclusion, we have designed and synthesized a new Coumarin-Ruthenium(II) polypyridyl complex having an extended
The authors are thankful to the IICT-Aisin Cosmos collaborative project for financial support of this work. L. Giribabu is thankful to the project SR/S1/IC21/2008 for partial financial support of this work. V. K. Singh and Ch. V. Kumar are thankful to Council of Scientific and Industrial Research (CSIR) for a fellowship.