A new kind of solvent-free eutectic melt electrolytes for dye-sensitized solar cells (DSCs) has been designed, which are composed of imidazolium salts (i.e. 1-methyl-3-acetylimidazolium iodide (MAII), 1-ethyl-3-methylimidazolium iodide (EMII)) and plastic crystal succinonitrile (SN). Differential scanning calorimetric measurement reveals that the eutectic melt mixture EMII/SN can exhibit stable liquid state in the whole temperature domain from −80 to 80 °C. Besides, the conductivities of the eutectic melt electrolytes are higher than conventional imidazolium-based ionic liquid, 1-propyl-3-methylimidazolium iodide (PMII). Up to 7.46% of light-to-electricity conversion efficiency has been achieved by using the SN-based eutectic melt electrolyte, higher than PMII-based DSCs. Besides, the devices based on eutectic melt electrolytes exhibit good thermal stability. These results show that succinonitrile-based eutectic melts as environmentally friendly electrolytes, possess great potential for large-scale outdoor application of DSCs.

Low-cost bendable photoanodes and counter electrodes (CEs), as well as gel electrolytes, are potentially desired for the mass production of completely flexible dye-sensitized solar cells (DSSCs). In this work, via printing at low temperature, we fabricated titanium carbide (TiC)-functionalized conductive-carbon (CC) on flexible polyimide (PI) films to replace traditional and expensive Pt/ITO/PEN CEs. Morphology characterization revealed this composite CE was highly porous and homogeneous. Electrochemical investigations demonstrated that this Pt-and-ITO free flexible CE exhibited a high electro-catalytic activity. Finally, the conversion efficiencies of the all flexible quasi-solid DSSCs using this low-cost TiC-CC/PI CE achieved 86% of that based on a Pt/CC/PI CE. Thus, the facile fabrication process of this novel CE, along with its notable performance, are quite promising for the future roll-to-roll production of completely flexible DSSCs.

A transparent flexible Pt counter electrode (CE) was prepared on indium tin oxide-polyethylene naphthalate film using a simple dip coating method for dye-sensitized solar cells (DSCs), and a high catalytic activity was achieved. The DSC using this transparent flexible CE gave a power conversion efficiency (PCE) of 6.95% with front illumination, and a PCE of 5.18% with rear illumination.

The relationship between the integration of the incident photo-to-electron conversion efficiency (IPCE) and the measured short-circuit current density (JSC) of dye-sensitized solar cell (DSC) has been analyzed. The JSC of DSC under full sun is usually considered to be determined by the overlap between its spectral IPCE and the spectral photon flux incident on the cell. However, the IPCE spectrum has been found to be influenced by the bias light intensity in many practical cases. Through theoretical deduction, we have proved that JSC calculated from IPCE spectrum is related to the slope at corresponding incident light intensity on the short-circuit photocurrent density–incident light intensity (JSC−Elight) curve. The equal relation between JSC calculated from IPCE and JSC practically measured can only be obtained when the JSC−Elight curve is a straight line through the origin of the coordinates. The measured results of four DSC samples with different working condition show a good agreement with the theory. In addition, a simple method to validate the accuracy of IPCE measurement is also demonstrated.

The study of dye-sensitized solar cells (DSCs) has become an important research field for photovoltaic device development.We present a brief description of their basic structure,principle of operation,and essential component materials,as well as recent research progress.Emphasis is placed upon the design of DSC modules.Recent developments and problems are reviewed.

A new kind of quasi-solid state electrolytes for dye-sensitized solar cells (DSCs) has been prepared by in situ photopolymerization from the precursor 1,6-hexanediol diacrylate (HDDA) in 1-hexyl-3-methyl imidazolium iodide (HMII). The optimal ratio of polymer/ionic liquid is determined by the conductivities of the electrolytes. In order to further increase the miscibility between ionic liquid and the polymer, oligomer polyethylene glycol dimethyl ether (PEGDME) is introduced. By optimization of the amount of PEGDME in the electrolyte, the DSCs using this kind of solid-state electrolytes can present 6.5% of light-to-electricity conversion efficiency under 41mWcm−2. In the meantime, the influence of PEGDME additive is detailedly investigated by electrochemical impedance spectrum (EIS) and intensity modulated photovoltage spectroscopy (IMVS) techniques. Preliminary long-term stability test revealed that this in situ photopolymerized electrolyte exhibits good stability after 1000h thermal test.

Dye sensitized solar cells (DSCs) are promising alternative to conventional Si-based solar cells due to their low cost, easy fabrication and relatively high conversion efficiency. In the DSC, the electrolyte plays an important role in the regeneration of dye molecules and the charge transportation. Although the DSCs based on the liquid electrolyte can present much better photovoltaic performance, the disadvantages of the liquid electrolytes (i. e. volatility and easy leakage) are supposed to reduce the long-term stability. Therefore, the development of (quasi) solid-state electrolytes is necessary and imperative. In this paper, the recent progress on the solid-state electrolytes and the prospects are given.

Nickel sulfides have been, for the first time, electrodeposited on transparent conductive glass by a facile periodic potential reversal (PR) technique to supersede Pt counter electrodes (CEs) of dye-sensitized solar cells (DSCs). The composition and electrochemical catalytic activity of the nickel sulfide films prepared by PR technique are different from those of the ones deposited by the commonly used potentiostatic (PS) technique. PR technique produces transparent single-component NiS, while co-deposition of Ni and NiS is found in the opaque films prepared by PS method. The nickel sulfide deposited by PR technique shows high catalytic activity for the reduction of I(3)(-) to I(-) in a DSC. DSC with the CE deposited by PR technique performs much better (6.82%) than that by PS method (3.22%), and is comparable to the device with conventional Pt coated CE (7.00%).

A novel freestanding poly (beta-hydroxyethyl methacrylate), PHEMA-based organogel electrolyte is developed simply by optimization of the solution polymerization in the same solvent as the organic electrolyte for dye-sensitized solar cells (DSCs). The room temperature ionic conductivity of the gel electrolyte is 4.54 x 10(-3) S cm(-1), and the conduction behavior can be well described by the free volume model. The quasi-solid-state dye-sensitized solar cell fabricated with this PHEMA-based polymer gel electrolyte can present high energy conversion efficiency up to 7.5%. Preliminary long-term stability test further reveals that this quasi-solid-state electrolyte exhibits good stability after 1000 h thermal test in comparison with the DSCs based on corresponding liquid electrolyte.

Highly efficient large scale flexible dye-sensitized solar cells (DSCs) were successfully designed and fabricated. By the introduction of a light scattering layer or pressure, the DSC efficiency was greatly improved. The flexible DSCs with a small surface area (0.4 cm × 0.4 cm) gave a high energy conversion efficiency of 5.50%. The energy conversion efficiencies of large area DSCs (2 cm×3 cm, active area of 2.7 cm) improved from 1.52% to 1.81% and 2.50% , which is an increase of 20.0% and 66.7% compared with the DSCs prepared without any treatment. The 5 cm×7 cm DSCs (active area of 16.2 cm) without any optimization showed an energy conversion efficiency of 1.60% under a sunlight intensity of 40 mW·cm-2. The mechanism for the improvement in efficiency was also studied. The results of electrochemical impedance spectroscopy (EIS) demonstrated that the pressure method can significantly reduce the series resistance (Rs) and the charge transfer resistance (Rct) in the TiO2/dye/electrolyte interface. Scanning electron microscopy (SEM) showed that the TiO2 particles were far more closely connected after pressing, which was helpful for electron transport in the TiO2 network as well as for dye adsorption. In addition, the photovoltaic parameters of these flexible DSCs were found to be stable after the 900 h stability tests. The experimental results obtained for these flexible DSCs can be used as a foundation for further basic research and for industrialization technical research. 2577 Acta Phys. ⁃Chim. Sin. 2011 Vol.27

A new series of electrolytes composed of LiI and acetamide have been investigated in dye-sensitized solar cells (DSSCs). These electrolytes melt at about 50 °C and their ionic conductivities vary drastically below and above the melting points (Tm). They tend to form large crystals at low temperature, leading to poor penetration and contact within porous TiO2 anode film. This shortage is improved by introducing nano-SiO2 particles into the electrolyte. A total conversion efficiencies (η) of 0.3% at 35 °C and 4.2% at 75 °C are achieved respectively under AM 1.5 simulated solar light illumination when a LiI/acetamide (1:16) electrolyte with 8 wt% nano-SiO2 is used. It is expected that the DSSC using phase transition electrolyte could show high efficiency for operation at high temperature and high stability for storage at low temperature.

Chemically crosslinked polyacrylamide-based hydrogel has been first used as the polymer matrix to prepare quasi-solid-state polysulfide electrolyte for CdS/CdSe co-sensitized solar cells (QDSCs). The room temperature ionic conductivity of the gel electrolyte reaches 0.093S·cm−1. QDSCs based on this quasi-solid-state electrolyte can present up to 4.0% of light-to-electricity conversion efficiency. Meanwhile, the interfacial recombination at TiO2/electrolyte interface of the cell is also investigated by Electrochemical Impedance Spectroscopy (EIS).

A two-compartment hybrid tandem cell comprising a dye-sensitized solar cell as top cell and a thermoelectric cell as bottom cell has been developed to increase the overall photovoltaic conversion efficiency by utilization of full solar spectrum. The photovoltaic properties of the four-wire and two-wire hybrid tandem cells have been characterized and the working principle has been demonstrated using the electron energy band diagram. For two-wire hybrid tandem cells, the overall conversion efficiency can be improved by optimal designing DSC module in order to match the output current of the selected thermoelectric cell. Comparing with the individual dye-sensitized solar cell, an efficiency increase of 10% has been obtained for the hybrid tandem cell. The incident light intensity has no influence on the matching of the two compartments of the two-wire hybrid tandem cell.

An in situ prepared AlI3-poly(ethylene oxide) (PEO) quasi-solid-state electrolyte for dye-sensitized solar cells (DSCs) has been obtained. An intensive interaction between Al3+ ions and oxygen atoms from PEO was studied. The molecular weight of the PEO has been revealed to strongly influence the photovoltaic performance, and PEO 1500 (Mw=1500) can give the highest conversion efficiency among the four kinds of PEOs. This dependence was further verified by electrochemical impedance spectra. After being optimized, the DSCs using the AlI3-PEO electrolyte showed 6.30% of conversion efficiency.

The dye-sensitized solar cell (DSC) as a low price photovoltaic technology has attracted widespread attention in recent years. During its progress to practical application, replacement of the liquid electrolytes by solid-state ones has been found to be necessary. Alternative solid-state electrolytes have thus been developed. This review deals with the recent progress of different solid-state electrolytes on DSCs. In particular, representative examples are highlighted with the results of our solid-state composite electrolytes based on addition compounds.

An overview of the progress in research of dye-sensitized solar cells(DSCs),including their key materials,e.g.photoanode,dye,electrolyte and counter electrode,is presented.Meanwhile,recent development and breakthroughs concerning up-sizing technology and integration of DSCs have been reviewed.

We prepared a new organic electrolyte by the reaction among acetylacetone, pyridine and iodine in 3-methoxypropionitrile. The UV-Visible spectra, conductivity measurement and ESI mass spectra were used to study this electrolyte. It was suggested that the quaternization reaction of pyridine took place in this electrolyte solution and two kinds of pyridinium iodide were formed. The efficiency of dye-sensitized solar cells (DSCs) using this electrolyte reaches 6.72%, which is higher than that of DSCs using LiI electrolyte and methylpropylimidazolium iodide electrolyte. It implies that these pyridinium iodides are effective alternative component of iodide for the electrolytes of DSCs. As this organic iodide electrolyte was in situ synthesized based on iodine instead of alkyl iodide, it will be cost-effective and facilitative for the production of DSCs. (C) 2007 Elsevier B.V. All rights reserved.