Controlling the synthesis of Bi2Se3 nanoplatelets

Abstract

Bismuth selenide (Bi2Se3) is an excellent topological insulator, making the material interesting for optoelectronics, spintronics, quantum computing and thermoelectronics. The properties depend on the dimension of the material. A 2D topological insulator features edge states, while a 3D topological insulator contains surface states. We synthesized ultrathin hexagonal Bi2Se3 nanoplatelets by a polyol hot injection method, in which a bismuth precursor is injected into a selenium precursor. We examined what happens in these precursors and in the reaction to Bi2Se3. By adjusting several parameters of the precursors, the morphology of the nanoplatelets was controlled. The shape was changed from triangular to hexagonal to circular, the lateral size was varied from 40 nm to a few micrometers and the thickness was altered from 1 nm to tenths of nanometers. The optical properties of platelets of different sizes and thicknesses were investigated with UV-Vis spectroscopy. This diverse variety of sizes and thicknesses of Bi2Se3 nanoplatelets has not been reported before and opens up exciting new prospects for exploring topological properties and practical applications.