Dye-sensitized solar cells (DSCs) have been explored for photovoltaic applications because of their low cost and impressive conversion efficiency.[1] A DSC with 10 % efficiency was first demonstrated by Grätzel and co-workers using N3 (cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4-dicarboxylate) ruthenium(II)) as a sensitizer.[2] Progress in optimizing ruthenium-based sensitizers for DSCs has been focused primarily on enhancing the light-harvesting ability, and redshifting the metal-to-ligand charge transfer (MLCT) band. [3][4][5][6][7][8][9][10] These results can be achieved by extending the conjugation length of the anchoring or ancillary ligand. [11][12][13][14][15] Furthermore, retaining the photoinduced interfacial charge separation between the dye molecules and TiO 2 is also a crucial strategy to enhance the performance of DSCs. [16] This strategy is beautifully demonstrated by adding a hole-transport segment on the dye molecule in all-solid-state DSCs. [17,18] However, this concept could not be applied to liquid-state DSCs, [19,20] probably because the ruthenium sensitizers have relatively low light-harvesting capacity and large molecular size.We have shown [21,22] that thiophene-derived units are the good candidates for increasing the conjugation length of the ancillary ligand to increase the light-harvesting ability and red-shift the MLCT band of a ruthenium complex. Herein we reveal that thiophene-derived species can be functionalized easily with a alkyl-substituted hole-transport moiety, such as bis(heptyl)carbazole. Ruthenium complexes with ligands functionalized by thiophene, carbazole, and alkyl chains can be regarded as supersensitizers. The efficiency of a liquidstate DSC based on one of these supersensitizers is 9.72 %, which is 1.2 % higher than that (8.51 %) of the N3-based cell at the same fabrication and efficiency measuring conditions. This is the first demonstration that a carbazole moiety in the dye can enhance the performance of a liquid-state DSC. Furthermore, the terminal alkyl chains on the ancillary ligand were also modulated to explore the impact of the sensitizer size on the cell performance in the DSC. In situ photoelectrochemical measurements were used for the first time to study the intramolecular electron-transfer processes of the oxidized dye.The structures of the supersensitizers CYC-B6S and CYC-B6L are depicted in Figure 1. The electronic absorption spectra of these supersensitizers and N3 measured in DMF are displayed in Figure 2, and the optical data are summarized in Table 1. The absorption spectra of the supersensitizers show that the band centered at around 550 nm (which is the characteristic metal-to-ligand charge-transfer (MLCT) transition) is stronger and more red-shifted than that for N3. These results indicate that the spectral response of ruthenium
Dye-sensitized solar cells (DSCs) have been explored for photovoltaic applications because of their low cost and impressive conversion efficiency.[1] A DSC with 10 % efficiency was first demonstrated by Grätzel and co-workers using N3 (cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4-dicarboxylate) ruthenium(II)) as a sensitizer.[2] Progress in optimizing ruthenium-based sensitizers for DSCs has been focused primarily on enhancing the light-harvesting ability, and redshifting the metal-to-ligand charge transfer (MLCT) band. [3][4][5][6][7][8][9][10] These results can be achieved by extending the conjugation length of the anchoring or ancillary ligand. [11][12][13][14][15] Furthermore, retaining the photoinduced interfacial charge separation between the dye molecules and TiO 2 is also a crucial strategy to enhance the performance of DSCs. [16] This strategy is beautifully demonstrated by adding a hole-transport segment on the dye molecule in all-solid-state DSCs. [17,18] However, this concept could not be applied to liquid-state DSCs, [19,20] probably because the ruthenium sensitizers have relatively low light-harvesting capacity and large molecular size.We have shown [21,22] that thiophene-derived units are the good candidates for increasing the conjugation length of the ancillary ligand to increase the light-harvesting ability and red-shift the MLCT band of a ruthenium complex. Herein we reveal that thiophene-derived species can be functionalized easily with a alkyl-substituted hole-transport moiety, such as bis(heptyl)carbazole. Ruthenium complexes with ligands functionalized by thiophene, carbazole, and alkyl chains can be regarded as supersensitizers. The efficiency of a liquidstate DSC based on one of these supersensitizers is 9.72 %, which is 1.2 % higher than that (8.51 %) of the N3-based cell at the same fabrication and efficiency measuring conditions. This is the first demonstration that a carbazole moiety in the dye can enhance the performance of a liquid-state DSC. Furthermore, the terminal alkyl chains on the ancillary ligand were also modulated to explore the impact of the sensitizer size on the cell performance in the DSC. In situ photoelectrochemical measurements were used for the first time to study the intramolecular electron-transfer processes of the oxidized dye.The structures of the supersensitizers CYC-B6S and CYC-B6L are depicted in Figure 1. The electronic absorption spectra of these supersensitizers and N3 measured in DMF are displayed in Figure 2, and the optical data are summarized in Table 1. The absorption spectra of the supersensitizers show that the band centered at around 550 nm (which is the characteristic metal-to-ligand charge-transfer (MLCT) transition) is stronger and more red-shifted than that for N3. These results indicate that the spectral response of ruthenium
The Magnolia Champaca flower extract was used as green photo sensitizer with CTAB-EDTA systems for the enhancement of the conversion efficiency and storage capacity of photo galvanic cell for its commercial viability. Natural photo sensitizer (Magnolia Champaca extract) has been studied to obtain some insight with aim of finding relatively cheaper, cost effective and eco friendly photo sensitizer for further improvement in the electrical performance of galvanic cell. The observed cell performance in terms of photo potential, photocurrent, fill factor and storage capacity are 1080.0mV, 90.0μA, 0.40 and 40.0 minutes, respectively. The effects of different parameters on electrical output of the cell were observed and a mechanism has been proposed for generation of the photo potential and photocurrent in photo galvanic cell. Keywords: Magnolia Champaca Extract, CTAB, EDTA, photo potential, photocurrent I. INTRODUCTION Energy is one of the most fundamental and essential for development of nations. Energy is the lifeline of the country's economy and development. Because of the increasing demand in clean energy, solar energy is clean and renewable. In present the solar energy industry is one of the growing forces in renewable energy system .The device, in which convert solar energy into electrical energy are called solar cells. As long ago as in 1839 Becquerel observed that light can cause changes in the current and voltage characteristics of certain electrochemical cells After four year this concept of dye sensitization was carried out by Meyer from photography to photo electrochemical cells .Photo galvanic cells are under preliminary research stage these have high conversion efficiency but lacks storage capacity and the latter are found to have good storage capacity but low conversion efficiency. The success of any solar cell depends upon its power conversion efficiency. However, the worldwide demand for energy is expected to keep increasing at 5 percent each year [1]. Nowadays there are several major directions for solar technology development for photo galvanic that system directly converts the solar energy into electrical energy. Becquerel [2] first observed in 1839 the flow of current between two unsymmetrical illuminated metal electrodes in sunlight. Later, it was observed by Rideal [3] and Rabinowitch[4.] A dye sensitized solar cell which is based on a semiconductor formed between a photosensitized anode and on electrolyte systematic investigation was done [5]. And a metal based photo galvanic solar panel is the most commonly used solar technology to generate electrical energy was studied [6]. Use of some reductant and photo sensitizer in photo galvanic cells for solar energy conversion and storage was investigated [7]. The studies of photo galvanic cell consisting various dyes with reductant and surfactant were done [8]-[9]. Recently the photo galvanic effect in various interesting system were observed [10]-[11]. The photo chemical conversion of solar energy into electrical energy was studied [12]-[13]. Gangot...
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