Metal-Semiconductor Nanocomposites for High Efficiency Thermoelectric Power Generation

摘要

Demonstrated high ZT1.7 at 800K for the first time in nanostructured III-V material (0.12-0.5% ErAs:InGaAs). Successful electron transport modeling can explain temperature dependent Seebeck coefficient and mobility without fitting parameters. For the case of 0.8% TbAs:InGaAs, a ZT of 1.04 at 600K was demonstrated. Interestingly power factor enhancement for TbAs is much bigger than that for ErAs nanoparticles. However ErAs nanoparticles give higher thermal conductivity due to their smaller size (1nm vs. 2-5nm). Detailed experimental optimization of p-ErSb:InxGa1-xSb lead to ZT=0.57 at 530K. In the case of metal/semiconductor multilayers, observed giant cross-plane Seebeck coefficients of 2,560 microV/K at room temperature and 16,640 microV/K at 360 K, and extremely low room temperature thermal conductivity of 0.92 W/mK for La0.67Sr0.33MgO3/LaMnO3 perovskite oxide metal/semiconductor superlattices. Excellent agreement with the first principle calculations. First measurements of Seebeck for nitride superlattice (130 microV/K at 700K). Matches theoretical Seebeck at high-temperatures. This corresponds to ZT>2.5 with measured thermal conductivity and theoretical electrical conductivity. Finally, demonstrated fast Seebeck mapping with a novel multi-probe scanning Seebeck system. This is now used by BSST (Gentherm) to study the uniformity of variety of TE materials. Finally performed a detailed cost/efficiency trade off analysis for TE power generation and first analytical calculation of stress in multi-leg TE modules. The new model shows that the shearing stress under temperature gradient can be significantly reduced with low fractional area coverage of TE elements.