Large-area two-dimensional bismuth selenide crystals synthesized by solution-based control of the nucleation environment

Abstract

Two-dimensional (2D) Bi₂Se₃ is one of the most studied nanomaterials in recent years because of its fascinating electronic properties. However, previous synthesis methods, especially solution-based methods, were not capable of growing laterally large 2D Bi₂Se₃ crystals (mostly up to a few micrometers), and thus its real application and in-depth study was practically impossible. In this communication, we report a simple, reliable two-step method to synthesize large (20–50 μm in the lateral diameter and 10–15 nm in the thickness) disks of Bi₂Se₃ in the presence of ethylenediamine-tetraacetic acid (EDTA) and chloride ion, where EDTA acts as a complexing agent with bismuth(III). Depending on the growth conditions, we obtained 2D Bi₂Se₃ crystals having either a flat or spiral surface. We have thoroughly characterized the morphology, crystal structures, and electrical properties of these new disks, and we also discussed a possible growth mechanism based on the control over the surface chemistry and the nucleation stage.