Study Of Dye-sensitized Solar Cells Research Articles

Effects of graphene counter electrode and CdSe quantum dots in TiO2and ZnO on dye-sensitized solar cell performance

SUMMARY Fabrication and performance study of dye-sensitized solar cells using different counter electrodes and photoanodes is reported. Spin coated, E-beam coated platinum, and graphene electrodes were used as counter electrodes. Different combinations of TiO2 nanoparticle and ZnO nanorods (NRs) with CdSe quantum dots were prepared and used as photoanodes. The photoanodes comprising of both ZnO NRs and TiO2 nanoparticles have shown improved performances in short-circuit current density and open-circuit voltage comparing the devices fabricated using only ZnO NR or TiO2 nanoparticles. The inclusion of CdSe quantum dots has been found to increase the performance of dye-sensitized solar cell for all the photoanodes. In case of counter electrodes, the cells fabricated with graphene showed improved performance. Copyright © 2014 John Wiley & Sons, Ltd.

Collaboration network and pattern analysis: case study of dye-sensitized solar cells

Nowadays, the development of emerging technology has become a double-edged sword in the scientific world. It can not only bring lots of innovation to society, but may also cause some terrible consequences due to its unknown factors. International collaboration may be able to reduce risks, which means a lot to the exploration of the emerging technology. Taking dye-sensitized solar cells (DSSCs) as an example, this paper examines the rapid growth of Chinese DSSCs research and the rise of collaboration between China and other countries/region. We use bibliometric and social network analysis methods to explore the patterns of scientific collaboration at country, institution and individual levels using data from the Science Citation Index. Examining overall trends shows that China has increased her position in DSSCs around the world. Furthermore, by focusing on the individual level, we find that the most influential authors tend to have fixed co-author networks and author name order, which is something worth considering. We use co-author analysis software independently developed to check three kinds of fixed co-author networks to explore author contributions, influence, and Author Activity Index rank in collaboration networks and use the rank we calculated to further explain author contributions in the networks. Results show that Chinese-X (e.g., Chinese-American) authors have pushed the collaboration between country and country and almost every kind of small network has a top author in it to gather others together. The modified author activity index rank list may reflect real research level. Author collaboration patterns have been impacted by the kinds of their institutions to some degree. These results can undoubtedly promote the international collaboration and the innovation process in the similar emerging technology fields.

Natural dye-based photoelectrode for improvement of solar cell performance

In the present paper, photovoltaic studies of dye-sensitized solar cells (DSSCs) based on betacyanin/TiO2 and betacyanin/WO3–TiO2 have been done. The cell performances were compared through I–V curves and wavelength dependant photocurrent measurements for the two new types of DSSCs. The TiO2-coated DSSC showed the photovoltage and photocurrent of 300 mV and 4.96 mA/cm2, whereas the cell employing WO3–TiO2 photoelectrode showed the values 435 mV and 9.86 mA/cm2, respectively. The conversion efficiency of TiO2 based dye-sensitized solar cell was found to be 0.69 %, while WO3–TiO2-based cell exhibited a higher conversion efficiency of 2.2 %. The better performance of the WO3–TiO2 dye-sensitized solar cell photoelectrode is thought to be due to an inherent energy barrier at the electrode/electrolyte interface leading to the reduced recombination of photoinduced electrons.

Reliability study of dye-sensitized solar cells by means of solar simulator and white LED

In this work, we take into account a LED-based light source as an alternative to AM1.5 solar simulator to perform the reliability study on dye-sensitized solar cells (DSCs). We performed accelerated optical stress by means of high power white LED and during stress we performed DC and EIS measurements with both white LED and AM1.5 solar simulator in order to find, if any, differences in kinetics degradation. During stress we also performed characterization measurements using monochromatic LED sources in order to understand if it adds more information about the DSCs degradation mechanism. We found that DC parameters feature different degradation rates depending on characterization source and differences also appear on degradation kinetics shape. The DSC characterization performed with monochromatic light sources show strong differences in degradation rate and in degradation kinetics shape as well depending on wavelength sources.

Photophysical properties and dye-sensitized solar cell studies on thiadiazole–triazole–chalcone dendrimers

Synthesis of charge-separable and hole-transporting dendrimers with chalcone at the periphery, thiadiazole as core and triazole as branching unit has been achieved through ‘click’ reaction. The dendrimers are used as a charge separator in dye-sensitized solar cells (DSSCs) and exhibit higher open-circuit voltage than the bare film through the suppression of back electron transfer. As the dendrimer generations increases the dimension of the dendrimer also increases, resulting in a stronger association with I3- redox couple and higher open-circuit.

-Quantum-Dot Sensitized Metal Oxide Photoelectrodes: Photoelectrochemistry and Photoinduced Absorption Spectroscopy

TiO2, ZnO nanoparticulate(-np), and ZnO-nanorod(-nr) electrodes have been modified with FeS2 (pyrite) nanoparticles. Quantum size effect is manifested by a blue shift in both absorption and photocurrent action spectra. PIA (photoinduced absorption spectroscopy), a multipurpose tool in the study of dye-sensitized solar cells, is used to study quantum-dot modified metal oxide (MO) nanostructured electrodes. The PIA spectra showed an evidence for long-lived photoinduced charge separation. Time-resolved PIA showed that recombination between electrons and holes occurs on a millisecond timescale. Incident-photon-to-current efficiencies at 400 nm are ranged between 13% and 25%. The better solar cell performance of FeS2 on ZnO-nr over ZnO-np can be ascribed to the faster, unidirectional e-transport channels through the ZnO-nr as well as the longer electron lifetimes. The lower performances of electrodes can be explained by the presence of FeS2 phases other than the photoactive pyrite phase, as evidenced from XRD study.

CdS-Sensitized ZnO Nanorod Photoelectrodes: Photoelectrochemistry and Photoinduced Absorption Spectroscopy

Thin films of ZnO semiconductor nanorods (ZnO-nr) of 6 μm length and thin ZnO nanoparticulate films (ZnO-np) have been prepared and modified with Q-dots CdS for comparison study. PIA (photoinduced absorption spectroscopy), a multipurpose tool in the study of dye-sensitized solar cells, is used to study a quantum-dot-modified metal-oxide nanostrucutred electrode. Q-dot CdS-sensitized ZnO-nr (1D network) sensitized photoelectrode has demonstrated best performances in both photoelectrical response (IPCE max = 92%) and broadening response into far visible comparing to ZnO-np-based CdS solar cell. Preadsorbing ZnO-nr with ZnO-np does not bring further improvement. Time constant for electron injection into ZnO-nr conduction band was relatively fast decay of 6.5 ms, similar to TiO2-coated CdS, and proves at least a well pore filling of ZnO-nr film by ultrafine CdS particles. Unidirectional electron transfer mechanistic in ZnO-nr has played a major role in these performances.

Study of Dye-Sensitized Solar Cells with Nanostructure Inn Compact Layer and Au Nano Particles

This study examined the nanostructure InN compact layer and Au nano particles to dye-sensitized solar cells (DSSCs).We presents the DSSCs with Nitrided indium compact layer (InN-CPL) prepared by radiofrequency magnetron sputtering and doping Au particle in photoelectrode. The InN-CPL effectively reduces the back reaction in the interface between the indium tin oxide (ITO) transparent conductive film and the electrolyte in the DSSC. The Au particles effect conduction band of the TiO2 to rise open-circuit voltage to 0.7 v. The Au particles effectively rise inject electrons efficiency. For the DSSC without InN-CPL, the short-circuit current density and solar energy conversion efficiency are 15.6 mA/cm2 and 6.35 %, respectively. However, DSSCs with InN-CPL effectively rise short-circuit current density. The DSSC fabricated on 90 nm InN-CPL and doping Au particle showed the maximum power conversion efficiency of 8.9 % (AM1.5G) due to effective prevention of the electron transfer to electrolyte.

Effect of metal-doping in TiO2 on fill factor of dye-sensitized solar cells

In the study of dye-sensitized solar cells (DSSCs), we find that fill factor (FF) increases with the doping amount of Zn(II) but decreases with the doping amount of W(VI) in TiO2. A single-diode model is established to analyze the dependence of FF on open-circuit voltage (Voc) and ideal factor (m). This model well explains the changes of FF caused by the doping element and amount, that is, FF increases with the ratio of Voc/m. This study will shed light on the influencing factors of FF and guide the design of new materials towards high FF for DSSCs.

FeS2 quantum dots sensitized nanostructured TiO2 solar cell: photoelectrochemical and photoinduced absorption spectroscopy studies

Thin films of nanostructured TiO2 have been modified with FeS2 (pyrite) nano-particles by a low temperature chemical reaction of iron pentacarbonyl with sulfur in xylene. Quantum size effects are manifested by the observation of a blue shift in both absorption and photocurrent action spectra. PIA (Photoinduced absorption spectroscopy), where the excitation is provided by a square-wave modulated (on/off) monochromatic light emitting diode, is a multipurpose tool in the study of dye-sensitized solar cells. Here, PIA is used to study quantum-dot modified TiO2 nanostructured electrodes. The PIA spectra obtained give evidence for long-lived photoinduced charge separation: electrons are injected into the metal oxide and holes are left behind in the FeS2 quantum dot. Time-resolved PIA shows that recombination between electrons and holes occurs on a millisecond timescale. The Incident-Photon-to-Current Efficiency of about 23 % was obtained at 400 nm excitation. The performances of TiO2 electrodes modified with FeS2 are relatively low, which is explained by the presence of FeS2 phases other than the photoactive pyrite phase, as follows from the XRD spectrum.

A comparative study of dye-sensitized solar cells added carbon nanotubes to electrolyte and counter electrodes

For the purpose of increasing the energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes (CNTs) were added to electrolyte and PtCl 4-treated electrode. We used two different powders containing single-wall CNT (SWCNT) and multi-wall CNT (MWCNT). We added CNTs to PtCl 4-treated electrode (called as CNT-counter electrode) or electrolyte (called as CNT-electrolyte) and then fabricated four kinds of DSSCs with SWCNT-counter electrode, MWCNT-counter electrode, SWCNT-electrolyte, and MWCNT-electrolyte. The efficiency of CNT-counter electrode DSSC was improved to 4.03% (SWCNT) and 4.36% (MWCNT), respectively. In case of CNT-electrolyte DSSC, MWCNT-electrolyte DSSC showed higher efficiency (4.2%) than SWCNT-electrolyte DSSC (3.62%). Compared with a standard DSSC without CNTs whose efficiency was 3.22%, the energy conversion efficiency increased up to about 26% and 24% for the MWCNT-electrode DSSC and the MWCNT-electrolyte DSSC, respectively.

Copper(i) complexes of 6,6′-disubstituted 2,2′-bipyridine dicarboxylic acids: new complexes for incorporation into copper-based dye sensitized solar cells (DSCs)

Synthetic approaches to 6,6'-disubstituted-2,2'-bipyridine ligands bearing carboxylic acid substituents at the 4,4' or 5,5'-positions are described. Copper(I) complexes with these ligands have been prepared for use in copper-based dye-sensitized solar cells. The single-crystal structures of 6,6'-dimethyl-2,2'-bipyridine-4,4'-dicarboxylic acid (H(2)4), [H(3)6][CF3CO2].2CF3CO2H (H(2)6 = 6,6'-diphenyl-2,2'-bipyridine-4,4'-dicarboxylic acid) and 4[Cu(H(2)2)(H2)].3H2O (H(2)2 = 6,6'-dimethyl-2,2'-bipyridine-5,5'-dicarboxylic acid) are described, as well as those of the intermediates (1E,5E)-1,6-di(2-furyl)hexa-1,5-diene-3,4-dione and 4,4'-di(2-furyl)-6,6'-dimethyl-2,2'-bipyridine (3), and the copper(I) complex [Cu(3)(2)][PF6]. The roles that classical and non-classical hydrogen bonding and pi-stacking interactions play in determining the solid-state packing in these structures are discussed. Preliminary studies of DSCs with these complexes are reported.

On the photophysical and electrochemical studies of dye-sensitized solar cells with the new dye CYC-B1

In this study, the photoelectrochemical characteristics of a ruthenium photosensitizer with an alkyl bithiophene group, designated as CYC-B1, are studied. The effect of mesoporous TiO 2 film thickness on the photovoltaic performance of CYC-B1 and N3 dye-sensitized solar cells was investigated. The performance of the dye-sensitized nanocrystalline TiO 2 solar cells (DSSC) fabricated using CYC-B1 dye-anchored TiO 2 photoelectrode showed a convincing enhancement in cell efficiency when the TiO 2 film thickness was increased from 3 μm (eff.=5.41%) to 6 μm (eff.=7.19%). The efficiency of the CYC-B1-sensitized DSSC was maximum at 6 μm of the TiO 2 film thickness, reached its limiting value and remained constant up to 53 μm, although a similar trend was also observed for N3 dye-sensitized DSSC, however, the maximum efficiency achieved was only at 27 μm thickness (eff.=6.75%). As expected, the photocurrent density generated in the DSSC modified by CYC-B1 dye is larger than that from N3 dye. The effect of guanidinium thiocyanate (GuSCN) (additive) addition to the electrolyte on the photovoltaic performance of DSSCs based on CYC-B1 was also investigated. Furthermore, the electrochemical impedance spectroscopy (EIS) technique and photo-transient laser method have been employed to analyze the charge transfer resistances ( R ct) and the lifetime of the injected electrons on the TiO 2 containing different thicknesses.

Photoinduced absorption spectroscopy as a tool in the study of dye-sensitized solar cells

Photoinduced absorption (PIA) spectroscopy, where the excitation is provided by a square-wave modulated (on/off) monochromatic light source, is a versatile tool in the study of dye-sensitized solar cells. Spectra of transient species, such as the oxidized dye, can easily be obtained and their kinetics can be explored using frequency or time-resolved techniques. Experimental PIA conditions can be kept close to typical solar cell operating conditions, allowing extraction of relevant time constants. PIA is also a suitable method to study the quality of pore filling in case of solid hole conductors. Dye molecules that are not in direct contact with the hole conductor will have long lifetimes in their oxidized state and appear clearly in the PIA spectrum. The basic principles of PIA are explained using the example of electron injection and recombination in dye-sensitized TiO 2 in the absence of redox electrolyte.

Impedance spectroscopy study of dye-sensitized solar cells with undoped spiro-OMeTAD as hole conductor

The photoelectrical properties of a solid state dye-sensitized (DSSC) solar cell with 2,2’,7,7’- tetrakis(N,N-di-p-methoxyphenilamine)-9,9’-spirobifluorene (Spiro-OMeTAD) as transparent hole conductor have been studied in comparison with liquid electrolyte DSSC. Measurements of photopotential decay, transient spectroscopy, and impedance spectroscopy show that the lower electron lifetime determines the lower efficiency of the solid state DSSC with respect to the liquid electrolyte cell. Due to the high transport resistance of pure spiro-OMeTAD the cell response is transport limited at the more positive potentials studied, but recombination dominates at the potentials near the maximum efficiency peak and more negative potentials. Low frequency capacities presented by the solid state cells are much smaller than those of respective liquid cell versions.