Indirect-To-Direct Band Gap Transition of One-Dimensional V(2)Se(9): Theoretical Study with Dispersion Energy Correction

[Image: see text] Recently, we synthesized a one-dimensional (1D) structure of V(2)Se(9). The 1D V(2)Se(9) resembles another 1D material, Nb(2)Se(9), which is expected to have a direct band gap. To determine the potential applications of this material, we calculated the band structures of 1D and bulk V(2)Se(9) using density functional theory by varying the number of chains and comparing their band structures and electronic properties with those of Nb(2)Se(9). The results showed that a small number of V(2)Se(9) chains have a direct band gap, whereas bulk V(2)Se(9) possesses an indirect band gap, like Nb(2)Se(9). We expect that V(2)Se(9) nanowires with diameters less than ∼20 Å would have direct band gaps. This indirect-to-direct band gap transition could lead to potential optoelectronic applications for this 1D material because materials with direct band gaps can absorb photons without being disturbed by phonons.