One-step ultra-rapid fabrication and thermoelectric properties of Cu₂Se bulk thermoelectric material

Cu₂Se is a promising material for high temperature thermoelectric energy conversion due to its unique combination of excellent electronic properties and low thermal conductivity owing to its ionic liquid characteristics at high temperature. In this paper, fully dense single-phase bulk Cu₂Se material was prepared by the combination of self-propagating high-temperature synthesis (SHS) with in situ quick pressing (QP) for the first time. This new approach shortens the duration of the synthesis from days to hours compared to conventional preparation methods. SHS-QP technique is an ultra-fast preparation method, which utilizes the heat released by the SHS reaction and an external applied pressure to achieve the synthesis and densification of materials in one-step. The ultra-fast process of the SHS-QP technique enables the fabrication of single-phase Cu₂Se bulk materials with relative density of over 98% and with precise control over the stoichiometry owing to the ability to suppress the Se vapor during the reaction. The SHS-QP prepared Cu₂Se samples exhibit excellent thermoelectric figure of merit, ZT ∼ 1.5 at 900 K, which is comparable to those of Cu₂Se materials prepared by conventional methods. This study opens a new avenue for the ultra-fast and low-cost fabrication of Cu₂Se thermoelectric materials.