The Experts below are selected from a list of 69747 Experts worldwide ranked by ideXlab platform
Hironori Arakawa - One of the best experts on this subject based on the ideXlab platform.
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effect of additives on the Photovoltaic Performance of coumarin dye sensitized nanocrystalline tio2 solar cells
Langmuir, 2004Co-Authors: Kohjiro Hara, Yasufumi Danoh, Chiaki Kasada, Yasuyo Ohga, Akira Shinpo, Sadaharu Suga, Kazuhiro Sayama, Hironori ArakawaAbstract:The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the Photovoltaic Performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amo...
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effect of additives on the Photovoltaic Performance of coumarin dye sensitized nanocrystalline tio2 solar cells
Langmuir, 2004Co-Authors: Kohjiro Hara, Yasufumi Danoh, Chiaki Kasada, Yasuyo Ohga, Akira Shinpo, Sadaharu Suga, Kazuhiro Sayama, Hironori ArakawaAbstract:The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the Photovoltaic Performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amount of TBP was adsorbed on the dye-coated TiO2 films in the presence of Li cations. This result suggests that TBP, like DCA, suppressed the dark current on the TiO2 surface, which resulted in the improved photovoltage.
Michael Gratzel - One of the best experts on this subject based on the ideXlab platform.
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the effect of hole transport material pore filling on Photovoltaic Performance in solid state dye sensitized solar cells
Advanced Energy Materials, 2011Co-Authors: John Melaskyriazi, Ikang Ding, Arianna Marchioro, Angela Punzi, Brian E Hardin, George F Burkhard, Nicolas Tetreault, Michael Gratzel, Jacquese Moser, Michael D McgeheeAbstract:A detailed investigation of the effect of hole transport material (HTM) pore fi lling on the Photovoltaic Performance of solid-state dye-sensitized solar cells (ss-DSCs) and the specifi c mechanisms involved is reported. It is demonstrated that the effi ciency and Photovoltaic characteristics of ss-DSCs improve with the pore fi lling fraction (PFF) of the HTM, 2,2’,7,7’-tetrakis-( N , N -di- p -methoxyphenylamine)9,9’-spirobifl uorene(spiro-OMeTAD). The mechanisms through which the improvement of Photovoltaic characteristics takes place were studied with transient absorption spectroscopy and transient photovoltage/photocurrent measurements. It is shown that as the spiroOMeTAD PFF is increased from 26% to 65%, there is a higher hole injection effi ciency from dye cations to spiro-OMeTAD because more dye molecules are covered with spiro-OMeTAD, an order-of-magnitude slower recombination rate because holes can diffuse further away from the dye/HTM interface, and a 50% higher ambipolar diffusion coeffi cient due to an improved percolation network. Device simulations predict that if 100% PFF could be achieved for thicker devices, the effi ciency of ss-DSCs using a conventional rutheniumdye would increase by 25% beyond its current value.
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effect of coadsorbent on the Photovoltaic Performance of squaraine sensitized nanocrystalline solar cells
Nanotechnology, 2008Co-Authors: Junho Yum, Michael Gratzel, Soojin Moon, Robin Humphrybaker, Pablo Walter, Thomas Geiger, Frank Nuesch, Mohammad Khaja NazeeruddinAbstract:The effect of chenodeoxycholic acid as the coadsorbent with a squaraine sensitizer on TiO2 nanocrystalline solar cells was investigated, and it was found that the coadsorbent prevents the squaraine sensitizer from aggregating on the TiO2 nanoparticles but reduces dye loading leading to an interdependent Photovoltaic Performance. Analysis of the absorption spectra, and incident monochromatic photon-to-current conversion efficiency data showed that the load of squaraine sensitizer as well as the appearance of H-aggregates is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid increases due to the enhanced electron lifetime in the TiO2 nanoparticles coupled with the band edge shift of TiO2 to negative potentials.
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effect of coadsorbent on the Photovoltaic Performance of zinc pthalocyanine sensitized solar cells
Langmuir, 2008Co-Authors: Junho Yum, Michael Gratzel, Robin Humphrybaker, Songrim Jang, Juanjose Cid, Tomas Torres, Mohammad Khaja NazeeruddinAbstract:The effect of chenodeoxycholic acid as a coadsorbent on TiO2 nanocrystalline solar cells incorporating phthalocyanine sensitizers was studied under various conditions. Adding chenodeoxycholic acid onto TiO2 nanoparticles not only reduces the adsorption of phthalocyanine sensitizers but also prevents sensitizer aggregation, leading to different Photovoltaic Performance. The inspection of IPCE and absorption spectra showed that the load of phthalocyanine sensitizers is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid coadsorbent increases due to the enhanced electron lifetime in TiO2 nanoparticles coupled with the band edge shift of TiO2 to negative potentials.
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correlation between Photovoltaic Performance and impedance spectroscopy of dye sensitized solar cells based on ionic liquids
Journal of Physical Chemistry C, 2007Co-Authors: Francisco Fabregatsantiago, Shaik Mohammed Zakeeruddin, Daibin Kuang, Juan Bisquert, Emilio Palomares, Luis Otero, Michael GratzelAbstract:In this work, we study the characteristics of dye-sensitized solar cells using an ionic liquid as the electrolyte and compare them with the response of a solvent-containing electrolyte cell. Impedance spectroscopy is used to derive the key circuit elements determining the Photovoltaic Performance of the cell. On the basis of this data, photocurrent voltage curves are calculated and compared with experimental results.
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improvement of the Photovoltaic Performance of solid state dye sensitized device by silver complexation of the sensitizer cis bis 4 4 dicarboxy 2 2 bipyridine bis isothiocyanato ruthenium ii
Applied Physics Letters, 2002Co-Authors: Jessica Kruger, Michael Gratzel, Robert Plass, Hansjorg MatthieuAbstract:The Photovoltaic Performance of solid-state dye-sensitized solar cells based on 2,2′7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spiro-bifluorene has been improved to 3.2% overall conversion efficiency under air mass (AM) 1.5 illumination by performing the dye adsorption in the presence of silver ions in the dye solution. The enhancement in overall device efficiency is a result of increased open circuit potential and short circuit current. Different spectroscopic methods, such as x-ray photoelectron, Fourier-transform infrared and UV-visible spectroscopy have been employed to scrutinize the impact of the silver on the dye-sensitized device. From spectroscopic evidence it is inferred that the silver is mainly binding to the sensitizer via the amphidentate thiocyanate, allowing the formation of ligand-bridged dye complexes.
Xiaomin Ren - One of the best experts on this subject based on the ideXlab platform.
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Photovoltaic Performance of a nanowire quantum dot hybrid nanostructure array solar cell
Nanoscale Research Letters, 2018Co-Authors: Xin Yan, Xia Zhang, Xiaomin RenAbstract:An innovative solar cell based on a nanowire/quantum dot hybrid nanostructure array is designed and analyzed. By growing multilayer InAs quantum dots on the sidewalls of GaAs nanowires, not only the absorption spectrum of GaAs nanowires is extended by quantum dots but also the light absorption of quantum dots is dramatically enhanced due to the light-trapping effect of the nanowire array. By incorporating five layers of InAs quantum dots into a 500-nm high-GaAs nanowire array, the power conversion efficiency enhancement induced by the quantum dots is six times higher than the power conversion efficiency enhancement in thin-film solar cells which contain the same amount of quantum dots, indicating that the nanowire array structure can benefit the Photovoltaic Performance of quantum dot solar cells.
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Photovoltaic Performance of a Nanowire/Quantum Dot Hybrid Nanostructure Array Solar Cell
SpringerOpen, 2018Co-Authors: Xin Yan, Xia Zhang, Xiaomin RenAbstract:Abstract An innovative solar cell based on a nanowire/quantum dot hybrid nanostructure array is designed and analyzed. By growing multilayer InAs quantum dots on the sidewalls of GaAs nanowires, not only the absorption spectrum of GaAs nanowires is extended by quantum dots but also the light absorption of quantum dots is dramatically enhanced due to the light-trapping effect of the nanowire array. By incorporating five layers of InAs quantum dots into a 500-nm high-GaAs nanowire array, the power conversion efficiency enhancement induced by the quantum dots is six times higher than the power conversion efficiency enhancement in thin-film solar cells which contain the same amount of quantum dots, indicating that the nanowire array structure can benefit the Photovoltaic Performance of quantum dot solar cells
Kohjiro Hara - One of the best experts on this subject based on the ideXlab platform.
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effect of additives on the Photovoltaic Performance of coumarin dye sensitized nanocrystalline tio2 solar cells
Langmuir, 2004Co-Authors: Kohjiro Hara, Yasufumi Danoh, Chiaki Kasada, Yasuyo Ohga, Akira Shinpo, Sadaharu Suga, Kazuhiro Sayama, Hironori ArakawaAbstract:The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the Photovoltaic Performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amo...
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effect of additives on the Photovoltaic Performance of coumarin dye sensitized nanocrystalline tio2 solar cells
Langmuir, 2004Co-Authors: Kohjiro Hara, Yasufumi Danoh, Chiaki Kasada, Yasuyo Ohga, Akira Shinpo, Sadaharu Suga, Kazuhiro Sayama, Hironori ArakawaAbstract:The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the Photovoltaic Performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amount of TBP was adsorbed on the dye-coated TiO2 films in the presence of Li cations. This result suggests that TBP, like DCA, suppressed the dark current on the TiO2 surface, which resulted in the improved photovoltage.
Xudong Jiang - One of the best experts on this subject based on the ideXlab platform.
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effects of alkyl side chains of double cable conjugated polymers on the Photovoltaic Performance of single component organic solar cells
Journal of Materials Chemistry C, 2021Co-Authors: Xudong Jiang, Wenyue Xue, Wenbin Lai, Dongdong Xia, Qiaomei ChenAbstract:In this work, the effects of alkyl side units of double-cable conjugated polymers on the Photovoltaic Performance of single-component organic solar cells (SCOSCs) were systematically studied. Four double-cable conjugated polymers with the same conjugated backbone, linker and naphthalene diimide (NDI) side units, but with distinct alkyl units from ethylhexyl, butyloctyl, hexyldecyl to octyldodecyl were designed and synthesized. These polymers exhibit similar absorption spectra and frontier energy levels, but show distinct crystallinity, charge carrier mobilities and Photovoltaic Performance. Several advanced techniques, including differential scanning calorimetry, atomic force microscopy and grazing-incidence wide-angle X-ray, reveal that double-cable conjugated polymers with longer side units exhibit high solubility, resulting in large fibrillar structures and low crystallinity. Therefore, double-cable polymers with longer alkyl side units exhibit low charge carrier mobilities and low efficiencies in SCOSCs. Our universal studies provide a good example to show the effect of alkyl side units in double-cable polymers on the Performance of SCOSCs, which is useful for designing new double-cable conjugated polymers.
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correlating crystallinity to Photovoltaic Performance in single component organic solar cells via conjugated backbone engineering
Dyes and Pigments, 2019Co-Authors: Shijie Liang, Xudong JiangAbstract:Abstract Single-component organic solar cells (SCOSCs) show high stability and simplified fabrication process compared to two-component bulk-heterojunction solar cells, but their Photovoltaic Performance is far to be optimized. The control of nanophase separation in single-component conjugated materials is one important factor to realize high Performance. In this work, we design three double-cable conjugated polymers with distinct backbones, and we showed how the crystallinity of conjugated backbones controlled the nanophase separation in the polymers. The polymers contain diketopyrrolopyrrole-based conjugated backbone and perylene bisimide side units, in which the copolymerized units were varied from one thiophene to two and three thiophenes. With the structural variations, we found that, the more thiophenes on the backbone, the better crystallinity of double-cables can be obtained, resulting in better charge transport. As consequence, the power conversion efficiencies can be varied from 0.59% to 2.12%. Our results reveal that by controlling the crystallinity of conjugated backbone, the nanophase separation of double-cable polymers can be improved, and hence high PCEs will be obtained in SCOSCs.
