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The role of additives in the performance of CsPbI3perovskite solar cells (PSCs) was investigated. Different kinds of cations and anions were used as additives in a N,N-dimethylformamide (DMF) solution containing CsI and PbI2(1:1 molar ratio). These include HI, HBr, HCl, NH4I, NH4Br, and NH4Cl. Additive cations (H+and NH4+) as well as halide ions (I–, Br–, and Cl–) are important for the properties of PSCs. Especially, the addition of iodine ion showed good characteristics compared to Br–and Cl–. Among the CsPbI3layers prepared with different kinds of additives and annealed at different temperatures, the X-ray diffraction peaks of CsPbI3were clearly found at 14° and 28° for the sample annealed at 150 °C with 50 μL of HI, suggesting the formation of a cubic structure at the low temperature of 150 °C. The field emission scanning electron microscopy images indicate that the surface of the perovskite layer with hydrogen halide additive (“H+”-based additive) is more uniform than that with ammonium additive. The roughness profiles determined by atomic force microscopy indicate that the CsPbI3film with HI additive shows the least roughness among the samples with H+-based additives. Therefore, the best power conversion efficiency (PCE) of 4.72% is obtained for CsPbI3PSCs annealed at 150 °C with HI (50 μL). The H+-based additives seem to react with PbI2in DMF solution, increasing the solubility of PbI2and thus lowering the processing temperature. Furthermore, the PCE of CH3NH3PbI3–xClxPSCs decreased from 7.45 to 0.23%, whereas that of CsPbI3PSCs with 50 μL of HI only decreased from 3.55 to 2.78% after exposing the samples to air for 3 h. These results indicate that H+-based additives, especially HI, have more impact on the CsPbI3PSCs in terms of lowering the processing temperature and improving the performance.

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Thin film photocatalysts of TiO2 coated on the glass were prepared to self-clean and eliminate air pollutants by spin coating process with Ti(OC3H7 i)4, including PEG. The surface structure of TiO2 films changed according to the molecular size of PEG. It was found that NOx was efficiently eliminated by the TiO2 film photocatalyst. The contact angle of water drop on the TiO2 films decreased to less than 10°. It revealed the hydrophilic property of TiO2 films. The morphology and the crystal structure of TiO2 films were affected most.

ZrO2-SiO2 coatings deposited on 316 L stainless steel were prepared to protect chemically the substrates by sol-gel process using Zr(OC3H7 n)4/Si(OC2H5)4 as precursors. The influence of the ZrO2-SiO2 coatings on the corrosion resistance of the 316 L stainless steel was evaluated with the potentiodynamic polarization curves in deareated 15% H2SO4 solutions at 25, 40 and 50 ℃ . Comparative test was performed on uncoated one. The values of the electrochemical parameters explain how. ZrO2-SiO2 films increase the resistance of stainless steel against corrosion.

Sol-gel coatings of TiO2 have been prepared from TiO2 sol and deposited by a dip-coating technique on 316L stainless steel sheets to study their electrochemical behavior in corrosive solutions. The influence of the coatings on the chemical corrosion of the substrate was evaluated by potentiodynamic polarization curves in different aqueous NaCl solution at 25℃. Comparative tests were performed on uncoated one. The thickness of the TiO2 coatings varied from 0.5~0.8 µm. The values of the electrochemical parameters allow for an explanation of the role of the TiO2 films in the increased resistance of stainless steel against corrosion in moderately aggressive environments.

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The shape of the polymers in the mixed alkoxide solutions of Si(OC2H5)4 and Zr(n-OC3H7)4 with various water contents (1, 2, 4, and 8 in molar ratio to alkoxide, r) and catalysts was examined by rheological measurements, and its relation with fiber drawing behavior of the solutions was described. It was found that fibers could be drawn in the viscosity range 1–100 P from the acid-catalyzed solutions with lower water contents of the molar ratio H2O/alkoxide, r=2. On the other hand, no fiber could be drawn from the acid-catalyzed solutions including a large amount of water (r=4) and the base-catalyzed solutions.