Low temperature sintering of aqueous TiO2 colloids for flexible, co-sensitized dye-sensitized solar cells

Colloidal TiO2 films have been prepared using a binder-free aqueous paste with Degussa P25 and hexafluorotitanic acid (H2TiF6), which was optimised for different substrates. Dye-sensitized solar cells (DSSC) fabricated using this paste were sintered at (ca. 393 K) and efficiencies (η) of 3.0, 4.2 and 6.1% were measured for devices using titanium foil (ca. 1 mm thickness), indium-doped tin oxide on polyethylene terephthalate (ITO-PET), and for co-sensitized devices on fluorine-doped tin oxide (FTO) glass substrates, respectively. Electrochemical impedance measurements show that the charge transport resistance is less consistent for devices fabricated at low sintering temperature (ca. 393 K) by comparison to devices sintered at 773 K. These measurements correlate with the increased variation in device efficiency (η) for low temperature sintered DSSC devices

Low temperature sintering of binder-containing TiO2/metal peroxide pastes for dye-sensitized solar cells

Nano-structured metal oxide films are key components of dye-sensitized (DSC) solar cells. Scaling such devices requires lower temperature processing to enable cheaper substrates to be used. In this context, we report a new and scalable method to sinter binder-containing metal oxide pastes to make DSC photo-electrodes at lower temperatures. Metal peroxide powders (CaO2, MgO2, or ZnO2) were added to terpineol-based P25 pastes containing ethyl cellulose binder or to commercial TiO2 paste (DSL18NR-T). Thermal analysis shows that binder decomposition occurs at 300 °C instead of the standard 450 °C for a TiO2-only paste and suggests that the metal peroxides act as combustion promoters releasing heat and oxygen within the film while heating. The data show that this heat and oxygen release coincide best with binder combustion for ZnO2 and DSC device tests show that adding ZnO2 to TiO2 pastes produces the best performances affording η = 7.5% for small devices (0.26 cm2) and η = 5.7% at 300 °C or 450 °C for DSL18NR-T/ZnO2 for larger (1 cm2) devices. To the best of our knowledge, the performance of the (0.26 cm2) cells is comparable to the highest efficiency devices reported for DSCs fabricated using low temperature methods. The device efficiency is most strongly linked with Jsc; BET and dye sorption measurements suggest that Jsc is linked with the metal oxide surface area and dye loading. The latter is linked to the availability of surface sorption sites for dye molecules which is strongly negatively affected by any residual organic binder which resulted from incomplete combustion

Analysis of biofilm and bacterial communities in the towel environment with daily use

Abstract Towels differ remarkably from other textile products in their fibre structure and usage, and microbial behaviours on towels remain underexplored. Thus, we evaluated biofilm formation on towels during use for 6 months in daily life and analysed its relationship with odour, dullness, and laundry habits. The towels exhibited odour and dullness after 2 months of use and biofilm structures were observed over the 6 months, especially in the ground warp part. Polysaccharides, proteins, nucleic acids, and viable counts on the towels increased over time. The microbiota was significantly different from that on human skin and clothing. Several species of Alphaproteobacteria were correlated with dullness intensity and the quantity of biofilm components. Therefore, bacterial species that specifically adapt to the towel fibre environment could form biofilms. Our results demonstrate bacterial diversity in textile products and suggest careful consideration of the textile fibre material, structure, and usage pattern to control bacterial communities