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Improved thermoelectric performance of α- and β- Cu2Se through suppression of hole density using extrinsic copper vacancies
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DOI：10.1016/j.cej.2024.157558.png)
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Abstract
En 中文
Modulating Cu+ ion disorder in Cu2Se can enable control over the polymorphism and the carrier density leading to enhanced thermoelectric properties for both alpha- and beta-Cu2Se. Here we report that the incorporation of Cr3+ into the Cu2Se crystal lattice facilitates the stabilization of alpha-Cu2Se at 300 K leading to a large (similar to 140%) reduction in the carrier density both below and above the phase transition. This is attributed to the reduction in the density of intrinsic copper interstitials (Cu-i(center dot)) within the Cu(2-delta-lambda)(Cr-Cu(..))(lambda)(V-Cu ')(delta)(Cu-i(x))(delta-2 lambda)(h(center dot))(delta-2 lambda)Se crystal lattice. Such optimization of the carrier density led to a large (63%) increase in the thermopower and a drastic (46%) reduction in the total thermal conductivity for both alpha- and beta-Cu2Se matrices. Consequently, a significant enhancement of the thermoelectric performance is observed in the entire temperature range from 300 K to 773 K. This results in high average ZT values for both alpha-Cu2Se (ZT(ave) = 0.60) and beta-Cu2Se (ZT(ave) = 0.97), which paves the way for both near room temperature and high temperatures applications. This work provides a new approach to optimize the thermoelectric performance of Cu2Se-based materials by leveraging the interaction between mobile intrinsic Cu-i(.) and extrinsic V-Cu ' to suppress the hole density.
Keywords:
Extrinsic copper vacancies
Hole density optimization
Intrinsic copper interstitials
Ultralow thermal conductivity
Cr-doped Cu2Se
Journal
IF:
13.2
Papers:
7.4W
Citations:
48.5W