Scalable solution assembly of nanosheets into high-performance flexible Bi0.5Sb1.5Te3 thin films for thermoelectric energy conversion

Two-dimensional nanostructures, such as nanosheets and nanoribbons, represent excellent dimension for efficient transport of electrons and phonons and thus are ideal building blocks for hierarchical assembly of functional microscale electronic and phonic structures. We report a convenient and scalable solution approach for the hierarchical assembly of two-dimensional Bi2Te3&Sb2Te3 nanosheets compounds on polyimide substrates to obtain flexible Bi0.5Sb1.5Te3 thin films. We show that the nanosheets can be assembled into compact Bi0.5Sb1.5Te3 films by a solution-processed method followed by annealing treatment. Flexible thin films from two-dimensional nanosheets assemblies exhibit excellent thermoelectric properties and flexibility. The films of Bi0.5Sb1.5Te3/polyimide can be folded and even bent to a crease without cracking. The simple techniques involved in obtaining these films could help facilitate the rapid fabrication of flexible thermoelectric devices, heralding what promises to be a new approach toward the development of next-generation thermoelectric refrigeration and power harvesting technologies. Image of the flexible high-performance thermoelectric thin film synthesized from the Bi2Te3&Sb2Te3 nanosheets compounds on polyimide substrates. Crease picture of the flexible thin film after folded by a pliers.