Cu₂Sn_1-xSi_x (Cu-Sn-Si) precursors were prepared by fine particle coating method, which is a low cost and a non-vacuum process, and then the Cu₂Sn_1-xSi_xS₃ (CTSiS) thin films were fabricated through a sulfurization process. The prepared CTSiS thin films were evaluated by XRD, EPMA.

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In our previous study, Cu-Sn precursor deposited by mist CVD was peeling due to volume expansion during sulfurization to obtain CTS. Therefore in this study, to deposit CTS thin film without sulfurization process, both Cu-Sn source and S source used simultaneously mist CVD method, which named dual-source mist CVD method, was applied. By adjusting the Cu and Sn lifting gases, the thin films were prepared with the band gap of monoclinic CTS, showing X-ray diffraction peaks attributed to(133), (333) and (200) peaks of monoclinic CTS and Raman peaks.

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ZnO seed layer was deposited on a conductive glass substrate by spin coating method, and n-type semiconductor ZnO nanorods were fabricated by hydrothermal synthesis method. Then, CuBr_1-xI_x (CuBrI), a p-type semiconductor, was deposited on the nanorods by dip coating method. The power generation was increased by varying the seed layer deposition conditions.

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Cu_xSn_1-yGe_yS₃(CTGS) which is composed of non-toxic elements is a promising candidate for the absorber layer of single junction solar cells. However, there are few reports on the basic properties of CTGS. Therefore, CTGS with Cupoor, Cu-almost stoichiometric, and Cu-rich compositions were prepared and the photoluminescence spectra were observed. As a result, dominated luminescence was observed around 1.4 eV, which has a sharp and slightly sharp peaks. The sharp and slightly sharp peaks were attributed to exciton and donor acceptor pair recombination luminescence, respectively. The slightly sharp peak was weak in Cu-rich composition, it is considered to be caused by Cu vacancy.

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The fabrication of Cu₂ZnGeS₄ (CZGS) was realized by depositing ZnS on a co-evaporated Cu₂GeS₃ film by RF sputtering, followed by sulfurizing. After sulfurization, CZGS thin films with Cu/Ge ratios of 2.1 and 1.6, and Zn/Ge ratios of 1.5 and 2.0 were obtained. The thin films obtained after sulfurization were assigned to tetragonal CZGS with ZnS segregation on the basis of X-ray diffraction and Raman measurements. The CZGS film with a Cu-poor and significantly Zn-rich composition showed a higher Voc and lower Jsc than did the CZGS film with a Cu-rich and Zn-rich composition. This suggests that good p-n junctions were formed in CZGS films with Cu-poor cells but the efficiency decreased because of the increase in series resistance due to ZnS segregation.

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