Synthesis, characterization, crystal structure prediction, and ab initio study of bandgap of Cu3VSe4

This study presents a solid state synthesis of single crystals of tricopper tetraselenidovanadate. Obtained single crystals are characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. X-ray diffraction studies confirm presence of single crystals of the title compound and the obtained crystal structure agrees with the one already reported for Cu3VSe4. SEM images show the compositional homogeneity of obtained crystals, while EDX investigation confirms the elemental composition of Cu3VSe4. Moreover, the evolutionary algorithm, Uspex, is used for crystal structure prediction of this compound. We found that it may occure in three different crystal structures (space groups: P-42m (no. 111), I-42m (no. 121), and P-43m (no. 215)), from which the observed experimentally cubic phase has the lowest energy. The ab initio study of the bandgap of Cu3VSe4 shows that it is indirect in nature for each polymorphic structure and varies in range 1.017–1.720 ​eV revealing potential of this compound for applications in photovoltaics. The Tauc plot for bulk cubic Cu3VSe4 reveals direct transition with bandgap value 1.38 ​eV lying near the most optimal range in the Schockley-Queisser limit.