Cu2ZnSnS4 (CZTS)‐based materials have a useful band gap and a high absorption coefficient; however, their power conversion efficiency is low compared with that of CdTe and Cu(In,Ga)Se2‐based solar cells. Two of the factors that strongly affect CZTS solar cell characteristics are the MoS2 layer and the presence of defects. In this study, Mo back‐contact layers were annealed to control MoS2 layer formation and the Na content in the Mo layer before the absorber precursor layer was deposited. The increase in oxygen content in the Mo layer suppressed MoS2 layer formation. In addition, the increase in Na diffusion during the initial stage of the absorber precursor deposition decreased the defect density in the absorber layer and in the absorber–buffer interface. These results were verified through measurements of the external quantum efficiency, the temperature dependence of the open‐circuit voltage (VOC), and admittance spectra. The current densities (JSC) and VOC, as well as the power conversion efficiencies, improved as the annealing temperature of the Mo layer increased, which suggests that CZTS solar cell characteristics can be improved by suppressing MoS2 layer formation and increasing Na content in the Mo layer before deposition of the absorber precursor layer. Copyright © 2014 John Wiley & Sons, Ltd.

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The effect of diluting asbestos stabilizer on its performance of suppressing the asbestos fibre release has been investigated in terms of its penetrability into ceiling materials containing asbestos fibres. The performance of a silicate stabilizer was determined for cases where the ceiling material was damaged by external factors. The higher dilution rate of the stabilizer resulted in lower viscosities and hence greater penetration depths into asbestos ceiling materials. In addition, for cases in which the diluted stabilizer was sprayed several times onto the ceiling materials, the released asbestos fibre concentration was shown to be reduced by approximately 89% compared to the case of damaged ceiling material. Furthermore, this held true in cases where treated ceiling materials were damaged. The optimum condition, considering both performance and efficiency, is for a stabilizer with distilled water to be applied onto the damaged asbestos ceiling materials several times.