High-Throughput Synthesis, Screening, and Scale-Up of Optimized Conducting Indium Tin Oxides.

A high-throughput optimization and subsequent scale-up methodology has been used for the synthesis of conductive tin-doped indium oxide (known as ITO) nanoparticles. ITO nanoparticles with up to 12 at % Sn were synthesized using a laboratory scale (15 g/hour by dry mass) continuous hydrothermal synthesis process, and the as-synthesized powders were characterized by powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy. Under standard synthetic conditions, either the cubic In2O3 phase, or a mixture of InO(OH) and In2O3 phases were observed in the as-synthesized materials. These materials were pressed into compacts and heat-treated in an inert atmosphere, and their electrical resistivities were then measured using the Van der Pauw method. Sn doping yielded resistivities of ∼ 10(-2) Ω cm for most samples with the lowest resistivity of 6.0 × 10(-3) Ω cm (exceptionally conductive for such pressed nanopowders) at a Sn concentration of 10 at %. Thereafter, the optimized lab-scale composition was scaled-up using a pilot-scale continuous hydrothermal synthesis process (at a rate of 100 g/hour by dry mass), and a comparable resistivity of 9.4 × 10(-3) Ω cm was obtained. The use of the synthesized TCO nanomaterials for thin film fabrication was finally demonstrated by deposition of a transparent, conductive film using a simple spin-coating process.

Electrophoretically deposited TiO2 compact layers using aqueous suspension for dye-sensitized solar cells.

TiO2 compact layers (CLs) prepared by electrophoretic deposition (EPD) from an aqueous nanoparticle suspension were used in dye-sensitized solar cells (DSSCs) to prevent charge recombination at the interface between the transparent fluorine-doped tin oxide (FTO) substrate and the electrolyte. The TiO2 nanopowder (ca. 4.5 nm diameter) suspension used in the EPD process was prepared via a continuous hydrothermal flow synthesis pilot plant (at a production rate of ca. 0.38 kg h(-1)). The optimal thickness of the TiO2 CL for DSSCs is about 115 nm. Compared to the DSSCs without a CL, the optimal cell has shown improved short-circuit current density (JSC) and solar energy conversion efficiency by 13.1% and 15.0%, respectively. The mechanism for improved performance has been studied by the measurements of dark current and electrochemical impedance spectra. The interfacial charge transfer resistance at the FTO/electrolyte interface is increased after fabricating a CL in the cell, indicating inhibited electron recombination at the interface.