Tuning the electronic properties of highly anisotropic 2D dangling-bond-free sheets from 1D V2Se9 chain structures

True one-dimensional (1D) van der Waals materials can form two-dimensional (2D) dangling-bond-free anisotropic surfaces. Dangling bonds on surfaces act as defects for transporting charge carriers. In this study, we consider true 1D materials to be V2Se9 chains, and then the electronic structures of 2D sheets composed of true 1D V2Se9 chains are calculated. The (010) plane has indirect bandgap with 0.757 eV (1.768 eV), while the (111x305;) plane shows a nearly direct bandgap of 1.047 eV (2.118 eV) for DFT-D3 (HSE06) correction, respectively. The (111x305;) plane of V2Se9 is expected to be used in optoelectronic devices because it contains a nearly direct bandgap. Partial charge analysis indicates that the (010) plane exhibits interchain interaction is stronger than the (111x305;) plane. To investigate the strain effect, we increased the interchain distance of planes until an indirect-to-direct bandgap transition occurred. The (010) plane then demonstrated a direct bandgap when interchain distance increased by 30%, while the (111x305;) plane demonstrated a direct bandgap when the interchain distance increased by 10%. In mechanical sensors, this change in the bandgap was induced by the interchain distance.