As the MX69 research buy reaction time is reduced from 16 to 12 h, the obtained sample still has the phase of kesterite in high purity and good crystallinity. However, as the reaction time is further reduced to 8 and 6 h, the obtained two samples show the weak impurity peaks located at 46.5° and 31.8°, respectively. These

results imply that pure kesterite CZTS can be produced by the hydrothermal process at 180°C for no less than 12 h. Figure 4 XRD patterns of the samples obtained at 180°C for different times. Microstructure, morphology, and optical absorption property Figure 5 shows SEM, TEM, and HRTEM images and a SAED pattern of the pure CZTS sample synthesized at 180°C for 12 h from

the reaction system containing 2 mmol of EDTA at 2:2:1 of Cu/Zn/Sn. ARS-1620 solubility dmso The SEM image (Figure 5a) reveals general morphologies of flower-like particles, which are assembled from nanoflakes. The sizes of the hierarchical particles range from 250 to 400 nm, much smaller than the microspheres (approximately 2.2 μm) prepared by the solvothermal method at 250°C for 8 h [18]. The observations of the CZTS sample by TEM and HRTEM were performed after it had been dispersed into ethanol by ultrasound. The TEM image (Figure 5b) C59 ic50 shows some hexagonal nanoflakes with ca. 20 nm in size, implying that the hierarchical CZTS particles have been disassembled into the nanoflakes by ultrasound. As shown from the HRTEM image (Figure 5c), the continuous lattice fringes throughout a particle indicate the single crystalline nature of the nanoscale flakes, which is further Lepirudin confirmed by the dotted SAED pattern recorded for a single particle (Figure 5d). The d-spacing value has been calculated to be 0.31 nm (Figure 5c), identical to the theoretical

value of 0.31 nm for (112) planes of kesterite CZTS. Figure 5 SEM, TEM, and HRTEM images and SAED pattern of the CZTS sample prepared by hydrothermal method. (a) SEM, (b) TEM, (c) HRTEM, and (d) SAED pattern. Some binary and ternary compounds including ZnS, Cu3SnS4, and Cu2SnS3 could be present as impurity in CZTS [35], and their PXRD patterns are similar to that of kesterite CZTS. As a result, it is hard to distinguish CZTS from those binary and ternary compounds by using XRD. In order to further confirm the phase composition of the hierarchical CZTS particles, room-temperature Raman spectroscopy has been employed due to the ability of this technique to distinguish between the CZTS phase and the ZnS, Cu3SnS4, and Cu2SnS3 phases. Figure 6 shows the room-temperature Raman spectrum of the hierarchical CZTS particles. The kesterite CZTS sample exhibits a high intensity peak at 330.