Zeqing Hu,Rong Wei,Chen Yan,Han Wan,Yu Liu,Longjiu Cheng,Zhou Li,Jiming Song
In this work, carrier concentration optimization and effective mass increase of Cu2GeSe3, which were considered to be a synergetic effect of electrical transport properties, were achieved by the co-doping of Bi and Zn on the Cu site. This effect led to a higher Seebeck coefficient of ∼307.76 μV K–1 at 723 K for the Cu1.988Bi0.01Zn0.002GeSe3 sample. This effect also resulted in a higher power factor of ∼8.66 μW cm–1 K–2 at 723 K and an average power factor of ∼6.29 μW cm–1 K–2 at the temperature range of 303–723 K for the Cu1.988Bi0.01Zn0.002GeSe3 sample, which were ∼135 and ∼196% larger than those of pristine Cu2GeSe3, respectively, and are among the highest value of the Cu2GeSe3-based sample. Benefiting from simultaneous optimization of the power factor, the maximum ZT of ∼0.75 for the Cu1.988Bi0.01Zn0.002GeSe3 sample at 723 K was obtained, which is ∼288% higher than that of Cu2GeSe3.
Zeqing Hu,Xiaolong Liang,Deming Dong,Kairui Zhang,Zhou Li,Jiming Song
The potential thermoelectric Cu 2 GeSe 3 is limited by the unfavorable exorbitant electrical conductivity and the subsequent high electrical thermal conductivity . In this regard, we highlight a compensatory compositing strategy to synergistically optimize its thermoelectric properties by adding GeSe second-phase. Experimental results demonstrated that the GeSe additive compensated the carrier concentration and mobility to some extent, which suppressed the exorbitant electrical conductivity and led to much reduced electrical thermal conductivity and the final low thermal conductivity in (GeSe) x (Cu 2 GeSe 3 ) 1–x composites. Meanwhile, due to the decreased carrier mobility , the GeSe additive could also increase the effective mass of the Cu 2 GeSe 3 matrix, which significantly enhanced the Seebeck coefficient and power factor. Finally, with the synergistically optimized electrical and thermal transport properties of Cu 2 GeSe 3 via GeSe addition, the final figure-of-merit ZT values of composites were significantly improved. The peak ZT of the average of three times trials of 0.49 was achieved at 723 K for (GeSe) 0.02 (Cu 2 GeSe 3 ) 0.98 composite, which was 188% higher than its pristine counterpart.
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