Electrical charges on the boundaries of topological insulators favour forward motion over back-scattering at impurities, producing low-dissipation, metallic states that exist up to room temperature in ambient conditions. These states have the promise to impact a broad range of applications from electronics to the production of energy, which is one reason why topological insulators have become the rising star in condensed-matter physics. There are many challenges in the processing of these exotic materials to use the metallic states in functional devices, and they present great opportunities for the chemistry and materials science research communities.
Scattering and energy dissipation are common in charge-transport processes. A major discovery of condensed-matter physics in the 1980s, the quantum Hall effect, is realized in electrons confined in two dimensions in the presence of a strong magnetic field, in which dissipationless current flows along the sample's edge. In the past few years, topological insulators have been found to have similar metallic states that are also transported in a low-dissipation state. The existence of these remarkable electronic states is due to an intrinsic interaction in solids — spin–orbit coupling, instead of an external applied metallic field — which has the potential to impact multiple areas of applications.
In this Perspective, we introduce the basic concepts and interesting properties of topological insulators. After a brief overview of this rapidly developing field, we discuss the materials challenges and chemical issues encountered in current research. We conclude with potential applications of these remarkable materials and the possible influence on many other areas.