Thermoelectric materials, like other electronic materials, require high carrier mobility, which is governed by carrier scattering potential. In addition to intrinsic acoustic phonon scattering, the extrinsic factors such as microstructure and atomic arrangement also have great influence on carrier transport in solids, e.g., the emerging thermoelectric material AgSbSe 2 with strong cation disorder. However, the experimental evaluation of total carrier scattering potential and distinguishing the contributions from intrinsic and extrinsic scatterings is challenging at present. Here, the time-resolved ultrafast spectroscopy analysis utilizing a pump-probe scheme is performed to characterize the charge carrier dynamics of AgSbSe 2 with femtosecond time resolution quantitatively. A significantly lowered total carrier scattering potential energy in Cd-doped AgSbSe 2 crystal is determined, resulting from the elimination of grain boundaries and the presence of short-range order that leads to a negative extrinsic scattering potential. The reduction in carrier scattering potential leads to a threefold increase in the average power factor from 323 to 723 K. A maximum thermoelectric figure of merit of 1.7 is achieved in high-quality AgSb 0.973 Cd 0.017 Se 2 crystal at 723 K, with the output efficiency of the single-leg thermoelectric device reaching a competitive value of 8%. This work reveals how to effectively characterize and modulate carrier scattering potential in thermoelectric compounds.
High-entropy materials have expanded the frontier for discovering uncharted physicochemical properties. The phenomenon of chemical fluctuation is ubiquitous in high-entropy materials, yet its role in the thermoelectric field is often overlooked. Herein, we designed and synthesized a series of (Mg0.94−nYb0.26Sr0.26Znm)(MgnCd0.69Zn0.69−mNax)(Sb1.74Ca0.26) samples characterized by ultrahigh configurational entropy. These samples exhibit a homogeneous single-phase structure at macroscopic and microscopic scales, yet display notable chemical fluctuations at the atomic to nanoscale. These fluctuations, along with the unusual atomic occupations, lead to an exceptionally low lattice thermal conductivity akin to that of amorphous materials. Combining the optimized carrier concentration and well-maintained carrier mobility, we ultimately achieved a high zT value of 1.2 at 750 kelvin, outperforming most previously reported AB2Sb2-type Zintls. This study underscores that the atomic to nanoscale chemical fluctuations are the crucial catalyst for the enhanced thermoelectric performance in high-entropy materials.
Man Cai,Zheng Xing,Chen Du,Xinyu Ding,Mengyu Zhang,Chengjin Zhou
The ecological risks brought by heavy metals and 4-monobromodiphenyl ether (BDE-3) copollutants are among the most common environmental contaminants. Heavy metals and other substrates are actively transported across cellular membranes by an ATP-binding cassette (ABC) transporter. Previous studies have suggested that phyllospheric yeast (Wickerhamomyces anomalus) can survive in BDE-3 and heavy metal environments. However, the underlying molecular mechanisms of BDE-3 and heavy metal tolerance are not clear. To assess the impact of the yeast transporter pdr15 gene on plant tolerance, tissue heavy metal levels, and BDE-3 levels, we heterologously expressed the gene in tobacco. Accumulating evidence has suggested that transgenic tobacco contributes to the reduction of plant damage by resulting in heavy metals and BDE-3 in specific subcellular organelles. Dimethyl ether and phthalic acid metabolism were the two main metabolic pathways for the toxicity-reducing effect. Our findings broaden the understanding of ABC transporter function and their regulatory metabolic pathways in heavy metal and BDE-3 co-contaminated resistance.
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