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The temperature and excitation intensity dependence of photoluminescence (PL) spectra from Cu2ZnSnS4 (CZTS) thin films with various chemical compositions was investigated. Three types of CZTS thin films were examined: Zn-rich (group A), Cu- and Zn-poor (group B), and Cu-rich and Zn-poor (group C). Groups A, B, and C gave PL spectra with peaks at around 1.2, 1.30, and 1.45 eV, respectively. These spectra exhibited large peak energy shifts to higher energies as the excitation intensity increased by more than 10 meV/decade due to potential fluctuations. The PL spectra of groups A and B can be attributed to band-to-impurity luminescence, and the origin of the spectra was found to be CuSn and VZn or [ VZn + SnZn], respectively. The potential fluctuations were estimated from the lower energy side of the PL spectra, and the Cu-poor samples exhibited smaller potential fluctuations. [ABSTRACT FROM AUTHOR]

Cu2SnS3 (CTS) is a promising compound for use as an absorber layer in thin-film solar cells because it is made up of low-cost and abundant elements. However, the band gap energy of 0.94 eV for monoclinic Cu2SnS3 is less than the optimal value for absorber layers in single-junction solar cells. On the other hand, the band gap energy of Cu2GeS3 (CGS) is approximately 1.5-1.6 eV. Therefore, in this study, we carried out the synthesis of Cu2Sn1− xGe xS3, which is a solid solution of Cu2SnS3 and Cu2GeS3. The structure of the prepared samples was investigated using X-ray diffraction and Raman analyses. Diffuse reflectance spectra were obtained using a UV-Vis-NIR spectrometer and used to estimate the band gap energy. In X-ray diffraction patterns from the synthesized compounds, the diffraction peaks were found to shift to higher 2 θ values with increasing x, indicating a decrease in the lattice constants. In addition, the estimated band gap energy increased from 0.86 to 1.53 eV with increasing x. Cu2Sn1 − xGe xS3 is, therefore, a potential candidate for use as the absorber layer in thin film solar cells because its band gap energy can be adjusted simply by varying its composition. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) thin films were prepared by annealing films of Cu2S, ZnS, and SnS2 precursors deposited on a soda-lime glass substrate by photochemical deposition (PCD) from an aqueous solution containing CuSO4, ZnSO4, SnSO4, and Na2S2O3. This paper discusses the effect of adding dextrin as a titrant during the PCD preparation of CZTS thin films. We investigated the effects of dextrin addition on the surface morphology of the resulting films. The surfaces of films prepared with added dextrin were composed of uniformly sized grains. The results also demonstrate that the surface morphology of photochemically deposited CZTS films can be smooth if the proper additives are employed. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) thin film solar cells have been fabricated using sol-gel sulfurizing method under non-vacuum processing. The solar cells structure is Al/ZnO:Al/CdS/ CZTS/Mo/Soda Lime Glass(SLG) substrate. In our previous reports, the surface of CZTS got rougher as the particle diameter increased. In addition, there were many spots where CZTS layer was not coated enough by ZnO:Al window layer. In this report, in order to improve conversion efficiency of the CZTS solar cells, we focus on the ZnO:Al layer and the effect of an increase in the number of ZnO:Al coating repetition and the dependence on drying time and temperature for ZnO:Al were investigated. Optimized conversion efficiency of 3.61% was achieved with 15 coating repetition of ZnO:Al layer coated at 350 °C and dried for 3 min. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cu2SnS3 (CTS) is a promising compound for use as an absorber layer in thin-film solar cells because it is made up of low-cost and abundant elements. However, the band gap energy of 0.94 eV for monoclinic Cu2SnS3 is less than the optimal value for absorber layers in single-junction solar cells. On the other hand, the band gap energy of Cu2GeS3 (CGS) is approximately 1.5-1.6 eV. Therefore, in this study, we carried out the synthesis of Cu2Sn1− xGe xS3, which is a solid solution of Cu2SnS3 and Cu2GeS3. The structure of the prepared samples was investigated using X-ray diffraction and Raman analyses. Diffuse reflectance spectra were obtained using a UV-Vis-NIR spectrometer and used to estimate the band gap energy. In X-ray diffraction patterns from the synthesized compounds, the diffraction peaks were found to shift to higher 2 θ values with increasing x, indicating a decrease in the lattice constants. In addition, the estimated band gap energy increased from 0.86 to 1.53 eV with increasing x. Cu2Sn1 − xGe xS3 is, therefore, a potential candidate for use as the absorber layer in thin film solar cells because its band gap energy can be adjusted simply by varying its composition. [ABSTRACT FROM AUTHOR]