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Abstract: ZnO porous thin films with nanowire structure were deposited by the one-step electrochemical deposition method. And a CdS layer was coated on the as-deposited ZnO nanowire thin films by successive ionic layer adsorption and reaction (SILAR) method to passivate surface states. Then the films were further sensitized by CdSe quantum dots (QDs) to serve as a photoanode for fabricating quantum dots-sensitized solar cells (QDSSCs). The effect of the CdS interfacial passivation layer on the performance of the QDSSCs was systematically investigated by varying the SILAR cycle number and heating the passivation layer. The amorphous CdS layer with an optimized thickness can effectively suppress the recombination of the injected electrons with holes on QDs and the redox electrolyte. The newly formed CdS layer on the surface of the ZnO nanowire thin film obviously prolongs the electron lifetime in the passivated ZnO nanoporous thin film because of the lower surface trap density in the ZnO nanowires after CdS deposition, which is favorable to the higher short-circuit photocurrent density (J sc). For the CdSe QDs-sensitized ZnO nanoporous thin film with the interfacial passivation layer, the J sc and conversion efficiency can reach a maximum of 8.36mAcm−2 and 2.36%, respectively. The conversion efficiency was improved by 83.47% compared with that of the cell based on the CdSe QDs-sensitized ZnO nanoporous thin film without CdS interfacial passivation (0.39%). [Copyright &y& Elsevier]

Abstract: A novel thixotropic composite electrolyte was fabricated by using the amine group-functionalized silica nanoparticles as the gelator of an ionic liquid-based electrolyte for dye-sensitized solar cells. The SEM image of electrode deposited with electrolyte confirms that the high viscous gel electrolyte has a good contact with TiO2 electrode ascribed to the thixotropic property of the electrolyte. Based on the thixotropic and ionic liquid based-electrolyte containing the amine group-functionalized silica particles, the cells show better performance owing to the increased open-circuit voltage than that of the liquid device, yield a high energy conversion efficiency of 6.69% under AM 1.5 illumination at 100mVcm−2 when the content of the amine group-functionalized silica is 15wt.% and exhibit a long-term stability without sealing. [Copyright &y& Elsevier]

Abstract: We prepared highly ordered titanium dioxide nanotube arrays (TNAs) by anodizing Ti foils in F− containing electrolyte. The thickness and dye loading amount of TNAs were 26μm and 1.06×10−7 molcm−2, respectively. TiO2 nanoparticles (TNPs) were electrophoretically deposited on the inner wall of nanotube to produce coated nanotube arrays (TNAP). The dye loading was increased to 1.56×10−7 molcm−2, and the electron transport rate improved. TNAs and TNAP were sensitized with ruthenium dye N3 to yield dye-sensitized TiO2 nanotube solar cells. The power conversion efficiency of TNA-based dye-sensitized solar cells (DSSCs) was 4.28%, whereas the efficiency of TNAP-based DSSCs increased to 6.28% when illuminated from the counter electrode. The increase of power conversion efficiency of TNAP-based DSSCs is ascribed to the increased surface area of TNAs and the faster electron transport rate. [Copyright &y& Elsevier]

A TiO 2 compact layer was coated on fluorine-doped tin oxide (FTO) glass substrate prior to deposition of SnO 2 nanocrystalline thin film to suppress backflow of electrons from FTO to the SnO 2 nanocrystalline thin film. The resultant thin film was used as a photoelectrode to fabricate dye-sensitized solar cell. For comparison, a SnO 2 compact layer was also prepared to discuss the effect of the TiO 2 compact layer on the electron backflow process. Compared with the dye-sensitized SnO 2 nanocrystalline thin film solar cell without the compact layer, light-to-electric conversion efficiency for the solar cell with the TiO 2 compact layer was improved by 82.1% and it was even improved by 41.7% compared with the cell with the SnO 2 compact layer. Electrochemical impedance spectroscopy and open-circuit voltage decay of dye-sensitized solar cells were measured to demonstrate the improvement mechanism due to the TiO 2 compact layer. Both recombination resistance at the photoelectrode/electrolyte interface and lifetime of electrons on the SnO 2 nanocrystalline thin film were increased due to introduction of the TiO 2 compact layer. Because the conduction band of TiO 2 is higher than that of SnO 2 , the TiO 2 compact layer acts as not only a physical barrier to separate FTO substrate from electrolyte, thus suppressing recombination of electrons on FTO with the electrolyte, but also a potential barrier to effectively block the backflow of electrons from FTO substrate to the SnO 2 thin film. [ABSTRACT FROM AUTHOR]

Abstract: Pt counter electrodes (CEs) with different platinum loading have been prepared using chemical reduced method on flexible indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) for dye-sensitized solar cells (DSSCs). H2PtCl6·6H2O terpineol solutions were screen printed on the transparent ITO-PEN substrates. After drying, H2PtCl6 was reduced by treating it in NaBH4 solution followed by the hydrothermal treatment at 100°C. The obtained Pt CEs with different Pt-loading (2.4–7.7μg/cm2) were characterized by SEM, XPS, electrochemical impedance and transmission spectrum measurement. The Pt CEs show high catalytic activity, low charge transfer resistance (0.26–1.38Ωcm2) and good light transmittance (about 70% at 400–800nm). The light-to-electricity conversion efficiency of the flexible DSSC fabricated with the prepared Pt CE and the TiO2 photoanode prepared on Ti substrate by screen printing technique attains 5.41% under the simulated AM 1.5 sunlight, which is almost same as that based on the thermal decomposited Pt CE on FTO-glass. Compared with other methods to prepare Pt CEs, chemical reduced method is simple and suitable for flexible polymer substrates and the large scale preparation of DSSCs. [Copyright &y& Elsevier]

Abstract: 1-Oligo(ethylene oxide)-3-methylimidazolium iodide (PEOMImI) was synthesized and applied to dye-sensitized solar cells (DSSCs) by blending it with different 1-alkyl-3-methylimidazolium iodides used as ionic liquid electrolytes. The 1-propyl-3-methylimidazolium iodide (PMII) blend enabled the DSSC to attain a higher solar energy conversion efficiency of 4.52% under a light intensity of 100mWcm−2. The addition of N-methylimidazole (NMBI) to the electrolytes increased the conversion efficiency as compared to DSSCs based on NMBI-free electrolytes. The addition of both 1-allyl-3-methylimidazolium iodide (AMII) and NMBI enabled DSSCs to reach their highest solar energy conversion efficiency of 6.14% under a light intensity of 100mWcm−2. The ionic conductivity and diffusion coefficient of the triiodide were found to be augmented dramatically after adding NMBI, which leads to an increase in the photocurrent density. The enhancement mechanism of NMBI in the electrolyte was investigated by Raman spectroscopy and differential scanning calorimetry, and it was mainly due to the enhancement of electron exchange in electrolytes. [Copyright &y& Elsevier]

Abstract: Poly(vinylpyridine-co-ethylene glycol methyl ether methacrylate) (P(VP-co-MEOMA)) and α,ω-diiodo poly(ethylene oxide-co-propylene oxide) (I[(EO)0.8-co-(PO)0.2] y I) were synthesized and used as chemically cross-linked precursors of the electrolyte for dye-sensitized solar cells. Meanwhile, α-iodo poly(ethylene oxide-co-propylene oxide) methyl ether (CH3O[(EO)0.8-co-(PO)0.2] x I) was synthesized and added into the electrolyte as an internal plasticizer. Novel polymer electrolyte resulting from chemically cross-linked precursors was obtained by the quaterisation at 90°C for 30min. The characteristics for this kind of electrolyte were investigated by means of ionic conductivity, thermogravimetric and photocurrent–voltage. The ambient ionic conductivity was significantly enhanced to 2.3×10−4 Scm−1 after introducing plasticizer, modified-ionic liquid. The weight loss of the solid state electrolyte at 200°C was 1.8%, and its decomposition temperature was 287°C. Solid state dye-sensitized solar cell based on chemically cross-linked electrolyte presented an overall conversion efficiency of 2.35% under AM1.5 irradiation (100mWcm−2). The as-fabricated device maintained 88% of its initial performance at room temperature even without sealing for 30 days, showing a good stability. [Copyright &y& Elsevier]

Abstract: A poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/SiO2 based nanocomposite polymer is prepared and employed in the construction of high efficiency all-solid-state dye-sensitized nanocrystalline solar cells. The introduction of low-molecular weight PEUR prepolymer into PEO electrolyte has greatly enhance the electrolyte performance by both improving the interfacial contact properties of electrode/electrolyte and decreasing the PEO crystallization, which were confirmed by XRD and SEM characteristics. The effects of polymer composition, nano SiO2 content on the ionic conductivity and I3 − ions diffusion of polymer-blend electrolyte are investigated. The optimized composition yields an energy conversion efficiency of 3.71% under irradiation by white light (100mWcm−2). [Copyright &y& Elsevier]

Abstract: Nanocrystalline TiO2 films were prepared on flexible Ti-metal sheets by electrophoretic deposition followed by chemical treatment with tetra-n-butyl titanate (TBT) and sintering at 450°C. X-ray diffraction (XRD) analysis indicates that TBT treatment led to the formation of additional anatase TiO2, which plays an important role in improving the interconnection between TiO2 particles, as well as the adherence of the film to the substrate, and in modifying the surface properties of the nanocrystalline particles. The effect of TBT treatment on the electron transport in the nanocrystalline films was studied by intensity-modulated photocurrent spectroscopy (IMPS). An increase in the conversion efficiency was obtained for the dye-sensitized solar cells with TBT-treated nanocrystalline TiO2 films. The cell performance was further optimized by designing nanocrystalline TiO2 films with a double-layer structure composed of a light-scattering layer and a transparent layer. The light-scattering effect of the double-layer nanocrystalline films was evaluated by diffuse reflectance spectra. Employing the double-layer nanocrystalline films as the photoelectrodes resulted in a significant improvement in the incident photo-to-current conversion efficiency of the corresponding cells due to enhanced solar absorption by light scattering. A high conversion efficiency of 6.33% was measured under illumination with 100mWcm−2 (AM 1.5) simulated sunlight. [Copyright &y& Elsevier]