I-doped Cu2Se nanocrystals for high-performance thermoelectric applications

Cu2Se is considered as a potential thermoelectric material due to its excellent electrical properties and relatively high ZT values. However, the temperature-dependent phase transition and expensive experimental preparation approach hamper its practical application. In this work, a series of Cu2Se1-xIx (x = 0, 0.02, 0.03, 0.04, 0.05) alloys were prepared by using the cheap and facile hydrothermal method in combination with vacuum hot pressing. The crystal structures of synthesized Cu2Se1-xIx (x <= 0.04) are identical to the cubic beta-Cu2Se. By doping with iodine, the thermoelectric figure of merit of Cu2Se could be greatly improved up to 1.1 at 773 K and the phase transition temperature was reduced to 380 K. Our results suggest a promising route to optimize the performance of Cu2Se-based materials for high performance thermoelectric applications. (C) 2018 Elsevier B.V. All rights reserved.