The influence of a prealloying process on the formation of MoSe2 and thus on the performance of Cu2ZnSnSe4 (CZTSe) solar cells is investigated using sputtering deposition and post‐annealing approaches. The dense alloy layer, which is made by a low‐temperature prealloying process, acts as a temporary Se diffusion barrier during a subsequent high‐temperature selenization process. The formation of thick interfacial MoSe2 can be suppressed effectively by this temporary barrier, cooperating with subsequent quick formation of compact CZTSe layer. The thickness of interfacial MoSe2 layer in CZTSe solar cells can be tailored by adjusting the preannealing process during selenization. As a consequence, the series resistance of CZTSe solar cells is reduced to a low level (≈0.6 Ω cm2), and the performance of CZTSe solar cells is improved significantly. A CZTSe solar cell with efficiency of 8.7% is fabricated.

A detailed TEM investigation on the microstructure of TiN/Si3N4 nanocomposite coatings, which is believed to be responsible for the coatings' remarkable mechanical properties, was carried out. Parallel simulation utilizing two-dimensional TiN/Si3N4 nanomultilayered coatings was further performed to study whether the variation of Si3N4 interlayer thickness has an influence on the coatings' microstructure and mechanical properties. The results revealed that, in nanocomposite coatings with high hardness, Si3N4 tissue has a thickness of about 0.5–0.7 nm and exists in the crystalline state. Low-energy coherent interfaces are formed between Si3N4 and neighbouring elongated TiN grains. For TiN/Si3N4 nanomultilayered coatings, Si3N4 modulation layers with thicknesses less than 0.7 nm were also found to crystallize and form coherent interfaces with the neighbouring TiN layers; at the same time, the hardness of the coatings is remarkably enhanced. When its thickness exceeds 1.0 nm, Si3N4 transformed its growth mode into amorphous and the coherent interfaces were damaged; as a consequence, hardness enhancements in the coatings vanished. The similarity of the microstructure and the mechanical properties response between nanocomposites and nanomultilayered coatings indicates that the crystallization of Si3N4 as well as the formation of coherent interfaces between TiN and Si3N4 is the main reason for the hardening of the nanocomposites.

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Microstructure, surface morphology, and mechanical properties of nanocrystalline TiN/amorphous Si 3 N 4 composite films synthesized by ion beam assisted deposition