Topological electrodes

Nature Chem. 4, 281–286 (2012)

Credit: © 2012 NPG

Topological insulators, materials that have a conductive surface but an insulative interior, have attracted much attention in recent years owing to their intriguing properties. Scientists have now shown that topological insulators could be used as transparent flexible electrodes for next-generation optoelectronics operating in the near-infrared regime. Hailin Peng and co-workers from Peking University, the University of Oxford and Stanford University fabricated thin, multilayer Bi₂Se₃ nanostructures onto mica substrates by van der Waals epitaxy. The resulting nanosheets functioned as transparent conductors with sheet resistances as low as 330 Ω □⁻¹ and transparencies exceeding 70% for wavelengths of 1–3 μm. Tests indicated a high degree of mechanical robustness, with the nanosheet electrodes proving durable to 1,000 bending cycles. The researchers say that the Bi₂Se₃ electrodes could prove useful for applications such as infrared imaging and sensing, near-infrared solar cells and optoelectronic devices for optical communication.