Here we report the development of quantum dot sensitized solar cells (QDSCs) using colloidal PbS and PbSeS quantum dots (QDs) and polysulfide electrolyte for high photocurrents. QDSCs have been prepared in a novel sensitizing way employing electrophoretic deposition (EPD) and protecting the colloidal QDs from corrosive electrolyte with a CdS coating. EPD allows a rapid, uniform, and effective sensitization with QDs, while the CdS coating stabilizes the electrode. The effect of electrophoretic deposition time and of colloidal QD size on cell efficiency is analyzed. Efficiencies as high as 2.1 ± 0.2% are reported.

Aqueous-based electrophoretic deposition (EPD) of titania nanoparticles (Evonic's P25) was successfully applied to the fabrication of mesoporous electrodes for dye-sensitized solar cells (DSSC). Poor film adhesion and cracking arising from the electrolysis of water and interstitial water evaporation during drying were largely overcome via the selection of low EPD operating current density/DC voltage (0.1 mA cm −2 /2.5-3.1 V) but more importantly the addition of zinc nitrate in a 5 vol.% isopropanol-water suspension. As a result, a composite nanostructured TiO 2 -ZnO film was fabricated. Photoelectrochemical characterization indicates that in-situ formation of ZnO causes suppression of charge recombination at the electrode/electrolyte interface thus prolonging photoelectron lifetime. A 5.01% conversion efficiency was obtained under 1 sun illumination (100 mW · cm −2 ) of a 13 μm thick single transparent film. The efficiency was further improved to 6.19% upon further optimization via multi-layer construction of the transparent anatase film (18 μm thick) by repeated cycles of EPD.The dye-sensitized solar cell (DSSC) is attracting tremendous interest as a third-generation renewable energy conversion device. [1][2][3][4] The mesoporous nanocrystaline titania thin film is in the heart of the DSSC. Among various fabrication methods, electrophoretic deposition (EPD) may provide process simplification, cost reduction and high throughput manufacturing capability. 3 Thus a number of recent reports have successfully demonstrated the fabrication of DSSC photoanodes by EPD on glass, 5 Ti foil 6 or conductive plastic materials. 7 However in all these EPD methods organic solvents and toxic additives were used which are not compatible with the principles of green chemistry. Use of water as solvent is preferred but this has been hampered by the use of high DC voltages that cause its decomposition and gas evolution preventing the growth of good quality mesoporous films. As a result very few research studies have sought to prepare mesoporous titania electrodes for DSSCs purposes by employing EPD in aqueous media. [8][9][10][11] Some of the measures taken in the past to overcome the problem due to water electrolysis in aqueous-based EPD involved lowering the applied current or adding ethanol to the suspension. The former results in general to long deposition time. With the addition of 10 vol.% ethanol, oxygen evolution at the anode appears to be prevented since the oxidation of ethanol occurs at a potential lower than that of water. 9 Thus, Zhao et al. 10 fabricated 2 μm thick films made by EPD (in 30% v/v ethanol/water mixture) of ordered titanate nanotubes or commercial P25 TiO 2 powder, and obtained respectively 3.79 and 2.89% efficiencies after annealing at 600 • C. Kim et al. 11 , on the other hand, prepared 10 μm thick films by EPD (in 30% v/v methanol/water mixture) of titanate nanotubes on FTO, which upon annealing at 450 and 500 • C showed efficiency of 4.25 and 6.71% respectively. To our knowledge, this is one of the highe...

Electrophoretic deposition (EPD) is employed successfully in a suspension of multicomponent TiO2 nanoparticulates of different sizes and morphologies to engineer a very robust bifunctional electrode structure for dye-sensitized solar cell (DSSC) applications that shows excellent light-harvesting and photoelectrochemical performance. Aqueous-synthesized anatase nanocrystallites and sub-micrometer-sized "sea urchin"-like rutile aggregates are formulated in a stable isopropanol suspension without resorting to binders or charging agents. Interestingly, extremely robust films are obtained because of the high surface reactivity, electrophoretic mobility, and unique morphology of the rutile aggregates. DSSCs built with the newly configured bifunctional electrode yielded a record efficiency (8.59 %) for EPD-fabricated devices without resorting to mechanical compression. Such green-engineered mesoporous electrode structures can be built on both metallic and plastic substrates and can find applications in various energy and environmental fields.

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In this work the potential of employing electrophoretic deposition (EPD) for fabricating Li-ion battery electrodes without using binders and in particular eliminating volatile and toxic organic solvents such as n-methyl 2-pyrrolidone (NMP) is demonstrated. The paper in particular describes the successful application of the EPD method to fabrication of thick (>20 μm) nano-TiO 2 /carbon Li-ion intercalation anodes. The EPD system involves deposition of commercial P25 TiO 2 nanoparticles and carbon black on aluminum foil from an isopropanol bath without making use of charging agents or other additives. Hetero-coagulation of TiO 2 and C particles in the isopropanol medium enabled their 80 V DC cathodic deposition into a well-adhered film with effective intermixing of active and conductive components. Electrochemical testing of the newly binder-free EPD-built electrodes revealed comparable film conductivity, polarization and charge storage capacity properties with the standard binder-based PVDF/NMP electrodes. Most importantly, the charge storage, cycling, and rate properties of the EPD-built electrodes were greatly enhanced by post-EPD sintering of the film at 450 • C. The combined EPD-sintering route resulted in a superior conductive percolating network by promoting nanoscale film composition uniformity, inter-particle necking, and favorable porous structure for enhanced interfacing with the liquid electrolyte. The sintered EPD-built electrode exhibited almost 50% higher capacity retention than that of the standard binder-based electrode upon cycling. EPD with its inherent self-assembling functionality and its overall operational simplicity provides an advantageous and green Li-ion electrode fabrication alternative. Lithium ion batteries (LIBs) are by far the most advanced electrochemical energy storage cells that are presently powering at an ever increasing pace not only mobile electronics but also electric transportation and renewable energy installations. [1][2][3][4] There is tremendous R&D effort in progress to develop increasingly higher performance electrode (anode and cathode) materials and electrolytes 5 to meet the new range of LIB applications, as is the case of electric vehicles. 6 However in this effort equally important is the selection of materials and fabrication technologies that not only lead to high energy and power density LIBs but also are governed by sustainability and affordability principles. It is in this context that the present work seeks to develop a green Li-ion fabrication technology featuring electrophoretic deposition and non-toxic abundant chemicals and materials.Present state-of-the-art electrode fabrication for lithium-ion batteries involves mixing the active powder material (anode or cathode), conductive carbon, and the binder (poly(vinilydene) fluoride, PVDF) by typically dispersing them in a solvent, then tape casting the slurry onto a current collector substrate, and finally followed by drying (at 120• C) and calendaring/pressing. 7 The high cost of PVDF binder and the require...