A strategy of surface modification to the mesoporous TiO2 photoanode with hydrochloric acid treatment was used in this study, and it was found that short circuit current and photovoltaic efficiency of dye-sensitized solar cells (DSSCs) were increased by 5.5% and 8.9% respectively. The improvement was attributed to the reduced impedances in the TiO2 film and at the TiO2/dye/electrolyte interface. It was showed that the increased surface electronic states could remarkably prolong electron lifetime, which was responsible for the reduction of impedances. Under these quasi-continuous states in mesoporous structure, the electron injection/transportation can be notably facilitated, which will be beneficial for the DSSC performance.

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.

Fluorine-doped tin oxide (FTO), one of the most popular transparent conductive oxide (TCO) materials, coated on glass has been used in various applications including many new-generation solar cells. However, there is a lack of reporting when it comes to FTO coated on flexible transparent substrate. For this paper, spray pyrolysis technique was used to have FTO firstly coated on to a brass substrate, which was then dissolved away after cementing an upper flexible transparent polyethylene terephthalate (PET) substrate, finally leaving high quality FTO film on PET substrate. Their structural, electrical, optical and flexible properties were investigated. The lowest resistivity was 7.6×10−4Ωcm, which is as good as conventional FTO deposited on glass. Their fold ability could be significantly improved to transcend commercial ITO/PET only by increasing the pretreating time of the brass substrate.

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 flexible composite electrode, which is composed of conducting polyaniline (PANI) as electroactive material and flexible graphite (FG) as conducting substrate, has been fabricated by in situ chemical polymerization to substitute for the expensive Pt counter electrode (CE) used in dye-sensitized solar cells (DSCs). The photovoltaic parameters of DSCs are strongly dependent on the oxidation state and the thickness of the PANI film. Higher photocurrent density and efficiency have been obtained by using emeraldine PANI compared to pernigraniline. The fabrication conditions, such as reaction time and initial monomer concentration, have been investigated to control the thickness of the PANI film. With initial monomer concentration of 0.3 M and reaction time of 60 min, an optimized PANI/FG composite CE with a PANI film thickness of 330 nm has been obtained. A DSC with the composite CE shows an overall conversion efficiency of 7.36%, which is comparable to 7.45% of that with Pt electrode under the same test condition. Facile charge-transfer and low sheet resistance of the composite electrode are suggested to be responsible for high performance of the DSC using such CE.

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.

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.

A new cyclic guanidinium ionic liquid OGI (1,3-dimethyl-2-N''-methyl-N''-octylimidazoguanidinium iodide) has been used as a quasi-solid-state electrolyte for dye-sensitized solar cells (DSCs), and 6.38% conversion efficiency was achieved at AM 1.5 simulated sunlight (9.81 mW cm(-2)). Further gelation with SiO2 nanoparticles afforded the solid-state electrolyte, which presented overall conversion efficiency of 5.85%. The diffusion properties of these OGI-based electrolytes were investigated. In the meantime, the optimal structure and ion-pairing interaction in OGI have been proposed by density functional theoretical calculation (DFT) at the B3LYP/6-21G(d,p) level. In view of the experimental and theoretical calculation results, it is suggested that high asymmetry and good charge delocalization of the cyclic guanidinium cation can well restrain the recombination reaction between the injected electrons in the TiO2 conduction band and I3- ions through its flexible hydrocarbon group, thus giving relatively high efficiency.

Porous carbon counter electrodes have been fabricated at low temperature by coating an organic binder free carbon slurry onto F-doped tin oxide conducting glass. The carbon slurry is prepared by ball-milling a dispersion of activated carbon in aqueous SnCl4 solution. During ball-milling, SnCl4 hydrolyzes and transforms into stannic acid gel, which acts as an inorganic "glue" to connect the carbon particles during film preparation. Dye-sensitized solar cells employing this carbon electrode achieve efficiency as high as 6.1% which is comparable to that of the cells using sputtering Pt as counter electrode.

A new method for generating hydrogen by the reaction of Al powder with water using iodine as additive is developed. I2 can penetrate through the surface oxide layer on aluminium to form AlI3. High solubility of AlI3 in water is benefited to activate Al surface. It is found that the production of hydrogen becomes significant above 60° C and obeys a logarithm rule. The pH value varies from 5 to 3 then back to 4.5 during the reaction, which is determined mainly by the kinetics of hydration reaction of AlI3 and the reaction of Al and HI produced spontaneously.

Dye-sensitized solar cell (DSC) consists a combination of several different materials: photoanodes with nanoparticulated semiconductors, sensitizers, electrolytes and counter electrodes (CEs). Each materials performs specific task for the conversion of solar energy into electricity. The main function of CE is to transfer electrons to the redox electrolyte and regenerate iodide ion. The work of CE is mainly focused on the studies of the kinetic performance and stability of the traditional CEs to improve the overall efficiency of DSC, seeking novel design concepts or new materials. In this review, the development and research progress of different CE materials and their electrochemical performance, and the problems are discussed.

We fabricated ZnO photoelectrodes at room temperature by doctor-blading ZnO gel; the adequate interparticle connection and the effective ammonia activation process improved the flexible DSC's efficiency to 3.8% (under 100 mW cm(-2)).